Workshop Manual C

Engine 2(0)

230, 250, 251DOHC

AQ131, AQ151, AQ171
 Workshop Manual
230, 250, 251DOHC,
AQ131, AQ151, AQ171
Index
Safety Precautions .............................................................................. 2
General information ............................................................................ 5
Repair instructions ............................................................................. 6
Presentation ........................................................................................ 8
Trouble-shooting Scheme ..................................................................11
1. Overhaul Data ............................................................................... 12
2. Special Tools ................................................................................20
3. Electrical System .........................................................................23
Wiring Diagram AQ131, AQ151, 230, 250 Alt. 1. ........................24
Wiring Diagram 230, 250 Alt. 2 ..................................................26
Wiring Diagram AQ171, 251DOHC Alt.1. .................................. 28
Wiring Diagram 251DOHC Alt. 2 ...............................................30
4A. Fuel System ..................................................................................32
Trouble shooting and Remedies Fuel System ............................32
Overhauling and checking the carburetor ...................................33
4B. Renix Ignition System ..................................................................38
Trouble-shooting and repair ignition system 251DOHC, AQ171 38
4C. Cylinder Head ............................................................................... 44
Removal of teh external components .........................................44
4D. Cooling System ............................................................................48
Overhauling the heat exchanger .................................................48
Overhauling the sea water pump ................................................ 49
Check the thermostat ..................................................................49
4E. Overhauling the valve system .....................................................50
Overhauling the valve system 230, 250, AQ131, AQ151 ...........50
Adjusting the valves 230, 250, AQ131, AQ151 ..........................59
Valve system 251DOHC, AQ171. Technical Description ...........61
Overhauling the valve system 251DOHC, AQ171 ......................63
4F. Installing the toothed belt ...........................................................71
Installing the toothed belt 230, 250, AQ131, AQ151 ......................71
Installing the toothed belt 251DOHC, AQ171 .................................73
4G. Installing the external components of the Cylinder Head ........74
5. Cylinder Block ..............................................................................78
5A. Removing the external components ........................................... 78
5B. Overhauling the Crank Assembly ...............................................80
The lubricating oil pump Overhauling ..........................................87
5C. Installing the external components ............................................93
Overhauling the oil cooler 250, 251DOHC, AQ151, AQ171 ........95

1
 Safety Precautions

Introduction
This Workshop Manual contains technical data, de- Check that the warning or information decals on
scriptions and repair instructions for Volvo Penta prod- the product are always clearly visible. Replace
ucts or product versions contained in the contents list. decals that have been damaged or painted over.
Ensure that the correct workshop literature is being
used. Engine with turbocharger: Never start the engine
without installing the air cleaner (ACL). The ro-
Read the safety information and the Workshop tating compressor in the Turbo can cause ser-
Manual “General Information” and “Repair Instruc- ious personal injury. Foreign objects entering
tions” carefully before starting work. the intake ducts can also cause mechanical
Important damage.

In this book and on the engine you will find the follow- Never use start spray or similar to start the en-
ing special warning symbols. gine. The starter element may cause an explo-
WARNING! If these instructions are not fol- sion in the inlet manifold. Danger of personal in-
lowed there is a danger of personal injury, ex- jury.
tensive damage to the product or serious me-
chanical malfunction. Avoid opening the filler cap for engine coolant
system (freshwater cooled engines) when the
IMPORTANT! Used to draw your attention to engine is still hot. Steam or hot coolant can
something that can cause damage, product spray out. Open the coolant filler cap carefully
malfunction or damage to property. and slowly to release pressure before removing
the cap completely. Take great care if a cock,
NOTE! Used to draw your attention to important in- plug or engine coolant line must be removed
formation that will facilitate work or operations. from a hot engine. It is difficult to anticipate in
which direction steam or hot coolant can spray
Below is a summary of the risks and safety precau-
out.
tions you should always observe or carry out when
operating or servicing the engine.
Hot oil can cause burns. Avoid skin contact with
hot oil. Ensure that the lubrication system is not
under pressure before commencing work on it.
Immobilize the engine by turning off the power Never start or operate the engine with the oil
supply to the engine at the main switch (switch- filler cap removed, otherwise oil could be
es) and lock it (them) in the OFF position before ejected.
starting work. Set up a warning notice at the en-
gine control point or helm. Stop the engine and close the sea cock before
carrying out operations on the engine cooling
Generally, all servicing should be carried out system.
with the engine switched off. Some work (carry-
ing out certain adjustments for example) re-
quires the engine to be running. Approaching a Only start the engine in a well-ventilated area. If
running engine is dangerous. Loose clothing or operating the engine in an enclosed space, en-
long hair can fasten in rotating parts and cause sure that exhaust gases and crankcase ventila-
serious personal injury. If working in proximity tion emissions are ventilated out of the working
to a running engine, careless movements or a area.
dropped tool can result in personal injury. Avoid
burns. Take precautions to avoid hot surfaces
(exhausts, turbochargers, charge air pipes and
starter elements etc.) and liquids in supply lines
and hoses when the engine is running or has
been turned off immediately prior to starting
work on it. Reinstall all protective parts removed
during service operations before starting the en-
gine.

2
Always use protective goggles where there is Store oil and fuel-soaked rags and fuel and oil
a danger of pieces of metal, sparks from grind- filters safely. In certain conditions oil-soaked
ing, acid or other chemicals being thrown into rags can spontaneously ignite. Used fuel and
your eyes. Your eyes are very sensitive, injury oil filters are environmentally dangerous waste
can lead to loss of sight! and must be deposited at an approved site for
destruction together with used lubricating oil,
Avoid skin contact with oil. Long-term or re- contaminated fuel, paint remnants, solvent, de-
peated contact with oil can remove the natural greasing agents and waste from washing
oils from your skin. The result can be irritation, parts.
dry skin, eczema and other skin problems.
Used oil is more dangerous to health than new Never allow a naked flame or electric sparks
oil. Use protective gloves and avoid using oil- near the batteries. Never smoke in proximity to
soaked clothes and rags. Wash regularly, es- the batteries. The batteries give off hydrogen
pecially before meals. Use the correct barrier gas during charging which when mixed with air
cream to prevent dry skin and to make clean- can form an explosive gas – oxyhydrogen.
ing your skin easier. This gas is easily ignited and highly volatile.
Incorrect connection of the battery can cause
Most chemicals used in products (engine and a spark which is sufficient to cause an explo-
transmission oils, glycol, petrol and diesel oil) sion with resulting damage. Do not disturb bat-
and workshop chemicals (solvents and paints) tery connections when starting the engine
are hazardous to health Read the instructions (spark risk) and do not lean over batteries.
on the product packaging carefully! Always fol-
low safety instructions (using breathing appa- Never mix up the positive and negative battery
ratus, protective goggles and gloves for ex- terminals when installing. Incorrect installation
ample). Ensure that other personnel are not can result in serious damage to electrical
unwittingly exposed to hazardous substances equipment. Refer to wiring diagrams.
(by breathing them in for example). Ensure
that ventilation is good. Handle used and ex- Always use protective goggles when charging
cess chemicals according to instructions. and handling batteries. The battery electrolyte
contains extremely corrosive sulfuric acid. If
Be extremely careful when tracing leaks in the this comes into contact with the skin, wash im-
fuel system and testing fuel injection nozzles. mediately with soap and plenty of water. If bat-
Use protective goggles! The jet ejected from a tery acid comes into contact with the eyes, im-
fuel injection nozzle is under very high pres- mediately flush with copious amounts of water
sure, it can penetrate body tissue and cause and obtain medical assistance.
serious injury There is a danger of blood poi-
soning. Turn off the engine and turn off power at main
switch(es) before carrying out work on the
All fuels and many chemicals are inflammable. electrical system.
Ensure that a naked flame or sparks cannot ig-
nite fuel or chemicals. Combined with air in Clutch adjustments must be carried out with
certain ratios, petrol, some solvents and hy- the engine turned off.
drogen from batteries are easily inflammable
and explosive. Smoking is prohibited! Ensure
that ventilation is good and that the necessary
safety precautions have been taken before
carrying out welding or grinding work. Always
have a fire extinguisher to hand in the work-
place.

3
 Use the lifting eyes mounted on the engine/re- Components in the electrical system, ignition
verse gear when lifting the drive unit. system (gasoline engines) and fuel system on
Always check that lifting equipment is in good Volvo Penta products are designed and con-
condition and has sufficient load capacity to lift structed to minimize the risk of fire and explo-
the engine (engine weight including reverse sion. The engine must not be run in areas
gear and any extra equipment installed). where there are explosive materials.
To ensure safe handling and to avoid damaging
Always use fuels recommended by Volvo Pen-
engine components on top of the engine, use a
ta. Refer to the Instruction Book. The use of
lifting beam to raise the engine. All chains and
lower quality fuels can damage the engine. On
cables should run parallel to each other and as
a diesel engine poor quality fuel can cause the
perpendicular as possible in relation to the top
control rod to seize and the engine to overrev
of the engine.
with the resulting risk of damage to the engine
If extra equipment is installed on the engine al- and personal injury. Poor fuel quality can also
tering its center of gravity, a special lifting de- lead to higher maintenance costs.
vice is required to achieve the correct balance
for safe handling.
Never carry out work on an engine suspended
on a hoist.

Never remove heavy components alone, even

where secure lifting equipment such as se-
cured blocks are being used. Even where lift-
ing equipment is being used it is best to carry
out the work with two people; one to operate
the lifting equipment and the other to ensure
that components are not trapped and damaged
when being lifted. When working on-board en-
sure that there is sufficient space to remove
components without danger of injury or dam-
age.

4
 General information
About the workshop manual Replacement parts
This workshop manual contains technical specifica- Replacement parts for electrical and fuel systems
tion, descriptions and instructions for repairing the are subject to statutory requirements (US Coast
standard versions of the following engines 230, 250, Guard Safety Regulations for example). Volvo Penta
251DOHC, AQ131, AQ151 and AQ171. The product Genuine parts meet these requirements. Any type of
designation and number should be given in all corre- damage which results from the use of non-original
spondence about the product. Volvo Penta replacement parts for the product will
not be covered under any warranty provided by Vol-
This Workshop Manual has been developed primarily
vo Penta.
for Volvo Penta service workshops and qualified per-
sonnel. Persons using this book are assumed to
have a grounding in marine drive systems and be
able to carry out related mechanical and electrical
work.
Volvo Penta is continuously developing their prod-
ucts. We therefore reserve the right to make
changes. All the information contained in this book is
based on product data available at the time of going
to print. Any essential changes or modifications in-
troduced into production or updated or revised ser-
vice methods introduced after the date of publication
will be provided in the form of Service Bulletins.

5
 Repair instructions
The working methods described in the Service Ma-
nual apply to work carried out in a workshop. The
Our joint responsibility
Each engine consists of many connected systems
engine has been removed from the boat and is in-
and components. If a component deviates from its
stalled in an engine fixture. Unless otherwise stated
technical specification the environmental impact of an
reconditioning work which can be carried out with
otherwise good engine may be increased significantly.
the engine in place follows the same working
It is therefore vital that wear tolerances are main-
method.
tained, that systems that can be adjusted are adjusted
Warning symbols occurring in the Workshop Manual properly and that Volvo Penta Genuine Parts as used.
(for their meaning see Safety information) The engine Maintenance Schedule must be followed.
WARNING! Some systems, such as the components in the fuel
system, require special expertise and special testing
equipment for service and maintenance. Some com-
IMPORTANT! ponents are sealed at the factory for environmental
reasons. No work should be carried out on sealed
components except by authorized personnel.
NOTE!
are not in any way comprehensive since it is impos- Bear in mind that most chemicals used on boats are
sible to predict every circumstance under which ser- harmful to the environment if used incorrectly.
vice work or repairs may be carried out. For this rea- Volvo Penta recommends the use of biodegradable
son we can only highlight the risks that can arise degreasing agents for cleaning engine components,
when work is carried out incorrectly in a well- unless otherwise stated in a workshop manual. Take
equipped workshop using working methods and special care when working on-board, that oil and
tools developed by us. waste is taken for destruction and is not accidentally
pumped into the environment with bilge water.
All procedures for which there are Volvo Penta spe-
cial tools in this Workshop Manual are carried out
using these. Special tools are developed to rational-
ize working methods and make procedures as safe Tightening torques
as possible. It is therefore the responsibility of any Tightening torques for vital joints that must be
person using tools or working methods other than tightened with a torque wrench are listed in workshop
the ones recommended by us to ensure that there is manual “Technical Data”: “Tightening Torques” and are
no danger of injury, damage or malfunction resulting contained in work descriptions in this Manual. All tor-
from these. ques apply for cleaned threads, screw heads and
In some cases there may be special safety precau- mating surfaces. Torques apply for lightly oiled or dry
tions and instructions for the use of tools and chem- threads. If lubricants, locking fluid or sealing com-
icals contained in this Workshop Manual. These spe- pound are required for a screwed joint this information
cial instructions should always be followed if there will be contained in the work description and in “Tight-
are no separate instructions in the Workshop Man- ening Torques” Where no tightening torque is stated for
ual. a joint use the general tightening torques according to
the tables below. The tightening torques stated are a
Certain elementary precautions and common sense guide and the joint does not have to be tightened using
can prevent most risks arising. A clean workplace a torque wrench.
and engine eliminates much of the danger of injury
and malfunction.
It is of the greatest importance that no dirt or foreign Dimension Tightening Torques
particles get into the fuel system, lubrication sys- Nm lbt.ft
tem, intake system, turbocharger, bearings and M5 6 4,4
seals when they are being worked on. The result M6 10 7,4
can be malfunction or a shorter operational life. M8 25 18,4
M10 50 36,9
M12 80 59,0
M14 140 103,3

6
Tightening torques-protractor Sealants
(angle) tightening A number of sealants and locking liquids are used on
the engines. The agents have varying properties and
Tightening using both a torque set- are used for different types of jointing strengths,
ting and a protractor angle requires operating temperature ranges, resistance to oil and
that first the recommended torque is other chemicals and for the different materials and
applied using a torque wrench and gap sizes in the engines.
then the recommended angle is
added according to the protractor To ensure service work is correctly carried out it is
scale. Example: a 90° protractor important that the correct sealant and locking fluid
tightening means that the joint is type is used on the joint where the agents are re-
tightened a further 1/4 turn in one quired.
operation after the stated tightening In this Volvo Penta Service Manual the user will find
torque has been applied. that each section where these agents are applied in
production states which type was used on the engine.
During service operations use the same agent or an
Locknuts alternative from a different manufacturer.
Do not re-use lock nuts that have been removed Make sure that mating surfaces are dry and free from
during dismantling as they have reduced service life oil, grease, paint and anti-corrosion agent before app-
when re-used – use new nuts when assembling or lying sealant or locking fluid. Always follow the
reinstalling. For lock nuts with a plastic insert such manufacturer’s instructions for use regarding; tempe-
as Nylock® the tightening torque stated in the table rature range, curing time and any other instructions
is reduced if the Nylock® nut has the same head for the product.
height as a standard hexagonal nut without plastic
Tow different basic types of agent are used on the
insert. Reduce the tightening torque by 25% for bolt
engine and these are:
size 8 mm or larger. Where Nylock® nuts are higher,
or of the same height as a standard hexagonal nut, RTV agent (Room temperature vulcanizing). Use for
the tightening torques given in the table apply. gaskets, sealing gasket joints or coating gaskets. RTV
agent is clearly visible when a component has been
dismantled; old RTV must be removed before the joint
is resealed.
Tolerance classes The following RTV agents are mentioned in the Ser-
Screws and nuts are divided into different strength vice Manual: Loctite® 574, Volvo Penta 840879-1,
classes, the class is indicated by the number on the Permatex® No. 3, Volvo Penta P/N 1161099-5, Perma-
bolt head. A high number indicates stronger material, tex® No. 77. Old sealant can be removed using methy-
for example a bolt marked 10-9 indicates a higher lated spirits in all cases.
tolerance than one marked 8-8. It is therefore im-
portant that bolts removed during the disassembly Anaerobic agents. These agents cure in an absence of
of a bolted joint must be reinstalled in their original air. They are used when two solid parts, for example
position when assembling the joint. If a bolt must be cast components, are installed face-to-face without a
replaced check in the replacement parts catalogue gasket. They are also commonly used to secure
to make sure the correct bolt is used. plugs, threads in stud bolts, cocks, oil pressure swit-
ches and so on. The cured material is glass-like and it
is therefore colored to make it visible. Cured anaer-
obic agents are extremely resistant to solvents and
the old agent cannot be removed. When reinstalling
the part is carefully degreased and then new sealant
is applied.
The following anaerobic agents are mentioned in the
Service Manual: Loctite® 572 (white), Loctite® 241
(blue).

NOTE! Loctite® is the registered trademark of Loctite Corpora-

tion, Permatex® is the registered trademark of the Permatex
Corporation.

7
 Presentation

230, AQ131 250, AQ151

251DOHC, AQ171
The engines are 4 cylinder gasoline engines. All the
engines are equipped with freshwater cooling in
combination with seawater cooling. The seawater
system is powered by a direct drive impeller pump.
The thermostat controlled freshwater system is pow- Product plate
ered by a circulation pump. The product plate is located on the cylinder block
The engines are manufactured with two different beside the starter motor. The product plate provides
product designations. During 1989 Volvo Penta be- the following information;
gan designating engines based on their cylinder dis- (1) Product designation, i.e. AQ131D
placement according to the ISO norm 8665. The
(2) Product number, i.e 867902
older product designations of AQ131, AQ151 and
AQ171 (where the number provided an approximate (3) Serial number (10 digit)
indication of output) were withdrawn. The new des- (4) Basic engine, serial number
ignation 230 replaced AQ131, 250 replaced
AQ151and 251DOHC replaced AQ171.
250, AQ151 and 251DOHC, AQ171 are equipped
with an oil cooler. 230, AQ131 has a single
carburettor and the others have twin carburettors.
The exhaust system has seawater cooled exhaust
pipes. 230, AQ131 and 250, AQ151 models have an
overhead camshaft while 251DOHC, AQ171 has
double overhead camshafts with hydraulic valve lift-
ers. 251DOHC, AQ171 is a 16 valve engine. 230,
AQ131 and 250, AQ151 models have conventional
marine ignition systems while 251DOHC, AQ171
has electronic ignition.
8
The Cooling System

The sea water cooling system

The fresh water cooling system, The fresh water cooling system,
thermostat closed thermostat open

1 = Sea-water filter
2 = Heat exchanger
3 = Sea-water pump
4 = Oil cooler
5 = Bypass
6 = Thermostat house
7 = Circulation pump

9
The Lubricating System

The engine lubricating system from strainer to the main gallery

The engine lubricating system from the main gallery to the lubricating points.

1 = Main gallery
2 = Oil pump
3 = Return line
4 = Oil cooler
5 = Oil filter

10
 Trouble-shooting Scheme
Engine Engine Engine does Engine runs Engine be-
does not stops not reach op- rough or vi- comes abnor- Fault reason
start erating speed brates abnor- mally hot
at full throttle mally
Main switch open. Battery
X discharged. Wires broken or
fuse blown.

Empty fuel tank, closed fuel cock,

X X clogged fuel filter.

X X X Water or impurities in the fuel.

X X X X Faulty spark plugs.

X Burned breaker points, moisture

in distributor and ignition leads.

X X Faulty electronic unit 251DOHC,

AQ171

X X Idling speed not adjusted properly.

X Faulty tachometer.

X Boat loaded abnormally.

X Growth on boat bottom and

sterndrive.

X Damaged propeller.

Clogged cooling water intake, oil

cooler (250, 251DOHC, AQ151,
X AQ171) waterjackets. Damaged
impeller or thermostat. Too low
coolant level in expansion tank

X Wrong fuel quality in relation to

timing

Toothed belt faulty or not adjusted

X X
properly.

11
 1. Overhaul Data
Technical Data
230, 250, 251DOHC
AQ131, AQ151, AQ171

General
Type designation ................................................................................. 230, AQ131
Type of engine ..................................................................................... 4 stroke, overhead cam
Speed range full load ........................................................................... 78.3–83.3 r/s (4700–5000 rpm)
Maximum cruising speed .................................................................... 3.33 r/s (200 rpm) lower than the max speed obtained
Compression ratio ............................................................................... 9.7:1
Compression pressure at starter motor speed1) .................................. 10–12 kp/cm2 (142–170 psi)
Number of cylinders ............................................................................ 4 in line
Cylinder bore ....................................................................................... 96 mm (3.7795")
Stroke .................................................................................................. 80 mm (3.1496")
Swept volume (displacement) ............................................................. 2.315 dm3 (141.3 in3)
Weight, excluding water and oil, approx. ............................................. 240 Kilos (529.1 lbs)
Idling speed ......................................................................................... 15 r/s (900 rpm)

General
Type designation ................................................................................. 250, AQ151
Type of engine ..................................................................................... 4 stroke, overhead cam
Speed range full load ........................................................................... 80–91.7 r/s (4800–5500 rpm)
Maximum cruising speed .................................................................... 3.33 r/s (200 rpm) lower than the max speed obtained
Compression ratio ............................................................................... 9.7:1
Compression pressure at starter motor speed1) .................................. 10–12 kp/cm2 (142–170 psi)
Number of cylinders ............................................................................ 4 in line
Bore ..................................................................................................... 96 mm (3.7795")
Stroke .................................................................................................. 86 mm (3.3858")
Swept volume (displacement) ............................................................. 2.49 dm3 (151.9 in3)
Weight, excluding water and oil, approx. ............................................. 250 Kilos (551.2 lbs)
Idling speed ......................................................................................... 15 r/s (900 rpm)

General
Type designation ................................................................................. 251DOHC, AQ171
Type of engine ..................................................................................... 4 stroke, overhead cams
Speed range full load ........................................................................... 83.3–95 r/s (5000–5700 rpm)
Maximum cruising speed .................................................................... 3.33 r/s (200 rpm) lower than the max speed obtained
Compression ratio ............................................................................... 9.7:1
Compression pressure at starter motor speed1) .................................. 10–12 kp/cm2 (142–170 psi)
Number of cylinders ............................................................................ 4 in line
Bore ..................................................................................................... 96 mm (3.7795")
Stroke .................................................................................................. 86 mm (3.3858")
Swept volume (displacement) ............................................................. 2.49 dm3 (151.9 in3)
Weight, excluding water and oil, approx. ............................................. 289 Kilos (637.15 lbs)
Idling speed ......................................................................................... 15 r/s (900 rpm)

1)
Applies to hot engine, wide open throttle

12
Cylinder block
Material ................................................................................................ Cast iron
Bore, standard ..................................................................................... 96.00–96.03 mm (3.7795–3.7807")
Bore, oversize 1 .................................................................................. 96.300 mm (3.79133")
Bore, oversize 2 .................................................................................. 96.600 mm (3.80315")
The cylinder bores should be bored at a wear depth of 0.10 mm
(0.004 in) (in case the engine has an abnormal oil consumption).

Pistons
Material ................................................................................................ Light alloy3)
Overall height 230, AQ131 .................................................................. 64.7 mm (2.54724")
Overall height 250, 251DOHC, AQ151, AQ171 .................................. 61.7 mm (2.42913")
Height from gudgeon pin center to top of piston
230, AQ131 ......................................................................................... 39.7 mm (1.56299")
Height from gudgeon pin center to top of piston
250, 251 DOHC, AQ151, AQ171 ........................................................ 36.7 mm (1.44488")
Piston clearance, production ............................................................... 0.010–0.030 mm (0.0004–0.0012")
Piston clearance, service .................................................................... max 0.080 mm (0.0031")
Piston, standard dimension ................................................................. 95.980–96.010 mm4) (3.779–3.780")
Piston, oversize 1 ................................................................................ 96.280–96.290 mm (3.791–3.7909")
Piston, oversize 2 ................................................................................ 96.580–96.590 mm (3.802–3.803")

3)
Maximum weight difference between pistons in the same engine is 16 grams (0.56 oz).
4)
See the spare parts catalog for all the products.

Piston rings
Piston ring end gap (oil scraper ring) ................................................... 0.30–0.60 mm (0.0118–0.0236")
Piston ring end gap (compression ring) ............................................... 0.30–0.55 mm (0.0118–0.0217")
Oversize piston rings 1 ....................................................................... 0.3 mm (0.0118")
Oversize piston rings 2 ....................................................................... 0.6 mm (0.0236")

Compression rings
The upper ring is chromium plated. The lower ring is marked “TOP”.
Number of rings on each piston ........................................................... 2
Height, upper ....................................................................................... 1.728–1.740 mm (0.068–0.069")
Height, lower ....................................................................................... 1.728–1.740 mm (0.068–0.069")
Piston ring clearance in groove, upper ................................................ 0.040–0.072 mm (0.0016–0.0028")
Piston ring clearance in groove, lower ................................................. 0.040–0.072 mm (0.0016–0.0028")

Oil scraper rings

Number on each piston ....................................................................... 1
Height .................................................................................................. 3.475–3.490 mm (0.1368–0.374")

Gudgeon pins
Full floating pin. Locked at both ends with circlips.
Fit in connecting rod ............................................................................ Light thumb pressure (push fit)
Fit in piston .......................................................................................... Thumb pressure (slide fit)
Standard diameter ............................................................................... 23.0 mm (0.906")
Oversize diameter ............................................................................... 23.05 mm (0.907")
Length ................................................................................................. 65 mm (2.559")

13
 AQ131A, 131B, AQ131C, 131D,
151A, 151B, 151C, 151D, 171C, 171D,
171A, 171B 230, 250, 251DOHC
Crankshaft
Crankshaft, axial clearance ................................................................. 0.080–0.270 mm 0.080–0.270 mm
(0.0031–0.0106") (0.0031–0.0106")
Main bearing, radial clearance ............................................................. 0.024–0.072 mm 0.024–0.064 mm
(0.00094–0.00283") (0.0009–0.0025")
Crank bearing, radial clearance .......................................................... 0.023–0.067 mm 0.023–0.067 mm
(0.00091–0.00264") (0.00091–0.00264")
Straightness, maximum deviation ........................................................ 0.025 mm 0.025 mm
(0.00098") (0.00098")

Taper Out-of-roundness
Main bearings
Main bearing journals
Out of roundness, max. ....................................................................... 0.004 mm 0.004 mm
(0.00016") (0.00016")
Taper, max. .......................................................................................... 0.004 mm 0.004 mm
(0.00016") (0.00016")
Standard diameter ............................................................................... 54.987–55.000 mm 62.987–63.000 mm
(2.1648–2.1654") (2.4798–2.4803")
0.25 mm undersize (0,0098") .............................................................. 54.737–54.750 mm 62.737–62.750 mm
(2.1550–2.1555") (2.4700–2.4705")
0.50 mm undersize (0,0197") .............................................................. 54.487–54.500 mm 62.487–62.500 mm
(2.1452–2.1457") (2.4601–2.4606")

Seat width on crankshaft for thrust bearings

Standard .............................................................................................. 31.96–32.00 mm 35.46–35.50 mm
(1.2583–1.2598") (1.3961–1.3976")
Oversize 1 ........................................................................................... 32.21–32.25 mm –
(1.2681–1.2697")
Oversize 2 ........................................................................................... 32.46–32.50 mm –
(1.2780–1.2795")

The main bearings are available in two makes. The upper and lower
main bearing shell on the same pivot must be of the same make.
In production matched crankshaft bearing shells are used. The
bearing shells are color coded, red, yellow and blue. They are matched
in accordance with one of the following alternatives:
Alternative 1: Two yellow-marked bearing shells.
Alternative 2: One blue-marked and one red-marked bearing shell. The
blue-marked shell to be located on the crankshaft and the red-marked
shell in the bearing cap.
NOTE! Only yellow-marked bearing shells are available for spare parts
purposes.

Connecting rods Color code

Connecting Rod Bearings
Bearing journals
Out of roundness, max. ....................................................................... 0.004 mm (0.00016")
Taper, max. .......................................................................................... 0.004 mm (0.00016")
Bearing seat width ............................................................................... 23.9–26.1 mm (0.9409–1.0276")
Standard diameter ............................................................................... 48.984–49.005 mm (1.9285–1.9293")
0.25 mm undersize (0.0098") .............................................................. 48.734–48.755 mm (1.9187–1.9195")
0.50 mm undersize (0.0197") .............................................................. 48.484–48.505 mm (1.9088–1.9096")
Axial clearance at the piston ............................................................... 0.25–0.45 mm (0.0098–0.0177")
Length, center to center ...................................................................... 152 mm (5.9843")
Max. weight difference between connecting rods in the same engine . 20 grams (0.7055 oz.)

14
Camshaft
Number of bearings ............................................................................. 5
Bearing, diameter ................................................................................ 29.95–29.97 mm (1.179–1.180")
Radial clearance ................................................................................. 0.030–0.071 mm (0.0012–0.0028")
Maximum ............................................................................................. 0.15 mm (0.0059")
Axial clearance (end play) ................................................................... 0.1–0.4 mm (0.0039–0.0157")

Camshaft bearings
Camshaft bearing diameter ................................................................. 30.000–30.021 mm (1.1811–1.1819")

Timing gears, Models 230, 250, AQ131, AQ151

Number of teeth, crankshaft gear ........................................................ 19
Number of teeth, intermediate shaft gear ............................................ 38
Number of teeth, camshaft gear .......................................................... 38
Number of teeth, toothed belt .............................................................. 123

Timing gears, Models 251DOHC, AQ171

Number of teeth, crankshaft gear ........................................................ 19
Number of teeth, intermediate shaft gear ............................................ 38
Number of teeth, camshaft gear .......................................................... 38
Number of teeth, toothed belt .............................................................. 146

Intermediate shaft
Number of bearings ............................................................................. 3
Front bearing diameter ......................................................................... 46.975–47.000 mm (1.849–1.850")
Middle bearing diameter ...................................................................... 43.025–43.050 mm (1.694–1.695")
Rear bearing diameter ......................................................................... 42.925–42.950 mm (1.690–1.691")
Radial clearance ................................................................................. 0.020–0.075 mm (0.0008–0.0030")
Axial clearance (end play) ................................................................... 0.20–0.46 mm (0.0079–0.0181")
Intermediate shaft bearing diameter in block:
Front ................................................................................................. 47.020–47.050 mm (1.851–1.852")
Middle .............................................................................................. 43.070–43.100 mm (1.696–1.697")
Rear ................................................................................................. 42.970–43.000 mm (1.692–1.693")

Changing the bearings

NOTE! New bearings must be line bored!

Valves 230, 250, AQ131, AQ151

Inlet
Disc diameter ...................................................................................... 44.0 mm (1.7323")
Stem diameter ..................................................................................... 7.955–7.970 mm (0.3132–0.3138")
Valve seat angle .................................................................................. 44.5°
Cylinder block seat angle .................................................................... 45°
Seat width in cylinder head .................................................................. 1.3–1.9 mm (0.0512–0.0748")

44.5°
New: 7.955–7.970 (0.3132–0.3138")
Min: 7.935 (0.3124")

44.0

Inlet valve

Exhaust
Disc diameter ...................................................................................... 35.0 mm (1.37795")
Stem diameter ..................................................................................... 7.945–7.960 mm (0.3128–0.3134")
Valve seat angle .................................................................................. 44.5°
Cylinder block seat angle .................................................................... 45°
Seat width in cylinder head .................................................................. 17–2.3 mm (0.0669–0.0906")

15
 44.5° New: 7.945–7.960 (0.3128–0.3134)
Min: 7.925 (0.3120")

35.0

Exhaust valve

IMPORTANT! The valves are stellite coated. Therefore they must not be machined, only lapped against the seat!

Clearance when checking:

Cold engine ......................................................................................... 0.30–0.40 mm (0.0118–0.0157")
Hot engine ........................................................................................... 0.35–0.45 mm (0.0138–0.0177")
Clearance when adjusting:
Cold engine ......................................................................................... 0.35–0.40 mm (0.0138–0.0157")
Hot engine ........................................................................................... 0.40–0.45 mm (0.0157–0.0177")
The same clearance for inlet and exhaust valves.

Valve guides (inlet & exhaust) 230, 250, AQ131, AQ151

Length ................................................................................................. 52 mm (2.165")
Inner diameter ..................................................................................... 8.00–8.02 mm (0.275–0.276")
Clearance, valve stem–valve guide, inlet valve ................................... 0.03–0.06 mm (0.0012–0.00245")
Clearance, valve stem–valve guide, exhaust valve ............................ 0.04–0.07 mm (0.0016–0.0028")
Clearance, maximum wear .................................................................. 0.15 mm (0.0059")

Valve springs, 230, 250, AQ131, AQ151

Length, unloaded ................................................................................. 45.0 mm (1.772")
Length, loaded 285–325 N (28.5–32.5 kp) ........................................... 38.0 mm (1.496")
Length, loaded 725–805 N (72.5–80.5 kp) ........................................... 27.0 mm (1.063")

Valves 251DOHC, AQ171

Inlet
Disc diameter ...................................................................................... 34.5 mm (1.358")
Stem diameter ..................................................................................... 6.955–6.970 mm (0.2738–0.2744")
Valve seat angle .................................................................................. 44.5°
Cylinder block seat angle .................................................................... 45°
Seat width in cylinder head .................................................................. 1.3–1.9 mm (0.0512–0.0748")

44.5°
New: 6.955–6.970 (0.2738–0.2744")
Min: 6.935 (0.2730")

34.5

Inlet valve

Exhaust
Disc diameter ...................................................................................... 31.5 mm (1.240")
Stem diameter ..................................................................................... 6.945–6.960 mm (0. 2734–0.2740")
Valve seat angle .................................................................................. 44.5°
Cylinder block seat angle .................................................................... 45°
Seat width in cylinder head .................................................................. 1.7–2.3 mm (0.0669–0.0906")

44.5°
New: 6.945–6.960 (0.2734–0.2740")
Min: 6.925 (0.2726")

31.5

Exhaust valve
IMPORTANT! The valves are stellite coated. Therefore they must not be machined, only lapped against the seat.

16
Valve clearance, 251DOHC, AQ171 ................................................... Hydraulic valve tappets, no setting is required

Valve guides (inlet & exhaust) 251DOHC, AQ171

Length ................................................................................................. 55 mm (2.165")
Inner diameter ..................................................................................... 7.00–7.02 mm (0.275–0.276")
Clearance, valve stem–valve guide, inlet valve ................................... 0.03–0.06 mm (0.0012–0.0024")
Clearance, valve stem–valve guide, exhaust valve ............................ 0.04–0.07 mm (0.0016–0.0028")
Clearance, maximum wear .................................................................. 0.15 mm (0.0059")

Valve springs 251DOHC, AQ171

Length, unloaded ................................................................................. 43.0 mm (1.6929")
Length, loaded 212–252 N (21.2–25.2 kp) ........................................... 37.0 mm (1.45669")
Length, loaded 600–680 N (60–68 kp) ................................................. 26.5 mm (1.0433")

Lubricating system
Changing oil, oil capacity, excluding filter ............................................ 3.5 dm3 (0.88 Imp gall./1.06 US gall.)
Changing oil, oil capacity, including filter ............................................. 4.0 dm3 (0.99 Imp gall./1.19 US gall.)
Oil pressure at 33.33 r/s (2000 rpm), hot engine ................................. 2.5–6.0 kp/cm2 (35–85 psi)
Lubricating oil, alternative 1 ................................................................. Volvo Penta lubricating oil for gasoline engines
Lubricating oil, alternative 2 ................................................................. Lubricating oil SG
Viscosity ............................................................................................. SAE 20 W/50

Oil filter
Type ..................................................................................................... Full flow filter

Lubricating oil pump

Axial clearance .................................................................................... 0.02–0.12 mm (0.0008–0.0047")
Radial clearance (excluding bearing clearance) .................................. 0.02–0.09 mm (0.0008–0.0035")
Gear backlash (excluding bearing clearance) ..................................... 0.15–0.35 mm (0.0059–0.0138")
Bearing clearance, drive shaft ............................................................. 0.032–0.070 mm (0.0013–0.0028")
Bearing clearance, idler shaft .............................................................. 0.014–0.043 mm (0.0006–0.0017")

Length of the relief valve spring at different loads:

Length: Load:
47.6 mm (1.874") No load
32.0 mm (1.26") 40–48 N (4.0–4.8 kp)
(29.4–35.2 ft.lbs)
26.0 mm (1.024") 55–67 N (5.5–6.7 kp)
(40.3–49.1 ft.lbs)

Fuel system
Fuel pump
Type ..................................................................................................... Diaphragm
Feed pressure ..................................................................................... 0.15–0.28 kp/cm2 (2–4 psi)
Fuel flow .............................................................................................. 1.6–2.0 liter/minute
(0.35–0.44 Imp.gal/min/0.375–0.475 US gal/min)

17
Carburetor 230, AQ131 AQ131A, 131B AQ131C,131D, 230
Type ..................................................................................................... Down draught Down draught
Designation ......................................................................................... Model 44 PAI-5 Model 44 PAI-7
Venturi ................................................................................................. 34 34
Main jet ................................................................................................ 165 165
Idling jet ............................................................................................... 65 65
Air jet ................................................................................................... 185 185
Needle valve ....................................................................................... 1.7 2.0
Float, weight in grams (oz’s) ................................................................ 7.3 (0.26) 7.3 (0.26)
Acceleration jet .................................................................................... 70 70
Econostat jet ....................................................................................... 110 110

Carburetor 250, AQ151 AQ151A, AQ151B AQ151C, AQ151D, 250

Type ..................................................................................................... Down draught Down draught
Designation ......................................................................................... Model 44 PAI-4 Model 44 PAI-7
Venturi ................................................................................................. 31 31
Main jet ................................................................................................ 145 145
Idling jet ............................................................................................... 62 62
Air jet ................................................................................................... 185 180
Needle valve ....................................................................................... 1.5 1.7
Float, weight in grams (oz’s) ................................................................ 7.3 (0.26) 7.3 (0.26)
Acceleration jet .................................................................................... 60 60
Econostat jet ....................................................................................... – –

AQ171C, AQ171D,
Carburetor 251DOHC, AQ171 AQ171A, AQ171B 251DOHC
Type ..................................................................................................... Down draught Down draught
Designation ......................................................................................... Model 44 PAI-5-6 Model 44 PAI-7
Venturi ................................................................................................. 32 32
Main jet ................................................................................................ 147 147
Idling jet ............................................................................................... 65 60
Air jet ................................................................................................... 190 200
Needle valve ....................................................................................... 1.7 1.7
Float, weight in grams (oz’s) ................................................................ 7.3 (0.26) 7.3 (0.26)
Acceleration jet .................................................................................... 70 70
Econostat jet ....................................................................................... – –

Electrical system
Battery
Grounding ............................................................................................ Negative
Voltage ................................................................................................ 12 Volts
Capacity .............................................................................................. 60 Ah
Specific weight of the electrolyte
Fully charged battery ........................................................................... 1.275–1.285 grams/cm3 (0.0460–0.0464 lb/cu.in.)
Discharged battery .............................................................................. 1.230 grams/cm3 (0.0444 lb/cu.in.)

Starter motor
Output ................................................................................................. 0.8 kW (1.1 hk)

Alternator
Output, maximum Amp (W) ................................................................. 50 (14x50)

Ignition system
Cylinder marking ................................................................................. No 4 closest to the flywheel
Spark plugs 230, 250, AQ131, AQ151 ................................................ Part no 875820-3, Bosch W6DC or its equivalent
Spark plugs, 251DOHC, AQ171 ......................................................... Part no 876077-9, Bosch WR6DC or its equivalent
Spark plug gap .................................................................................... 0.7 mm (0.0276")

18
Distributor 230, 250, AQ131, AQ151
Type ..................................................................................................... Breaker point system
Type Bosch JF4 .................................................................................. 0231 178 019

Setting for regular gasoline, min 91 octane ROT:

USA: Ignition setting for regular petrol (RON+MON)/2 = min 87 octane
Basic setting ........................................................................................ 6° BTDC (0–14.17 r/s = 0–850 rpm)
Stroboscope setting ............................................................................ 32–36° BTDC (70 r/s = 4200 rpm)
Contact gap ......................................................................................... 0.40 mm (0.01575")
Dwell angle .......................................................................................... 62±3°

Distributor, 251DOHC, AQ171

Type Bosch TVX4, Breakerless system .............................................. A 237 540 079

Setting for regular gasoline, min 91 octane ROT:

USA: Ignition setting for regular petrol (RON+MON)/2 = min 87 octane
Basic setting ........................................................................................ 10° BTDC (0–15 r/s = 0–900 rpm)
Stroboscope setting (not adjustable) ................................................... 23–25° BTDC (73.33 r/s=4400 rpm)

Cooling system
Thermostat
Type ..................................................................................................... Wax thermostat
Starts opening at ................................................................................. 82°C (179.6°F)
Fully open at ........................................................................................ 92°C (197.6°F)

Tightening torques
NOTE! Always tighten the cylinder head bolts when the
engine is cold. The torque values are valid for bolts and
nuts being well oiled prior to installation.
Parts having been washed should be oiled prior to
the assembly.

Tightening torque for cylinder head bolts:

The cylinder head: To be tightened in stages ....................................... 1 = 20 Nm (2.0 kpm) (15 ft.lbs.)
2 = 40 Nm (4.0 kpm) (29 ft.lbs.)
3 = Angle tighten through 120° in one operation!

– Replace the cylinder head bolts if they show signs of being

stretched. If a bolt is “stretched” can clearly be seen on the
“waist” of the bolt, which is then elongated.
– The cylinder head bolts can be “re-used” max 5 times.
Replace the bolts if you feel uncertain on any of these points.

Nm Kpm Ft.lbs.
Main bearings ...................................................................................... 110 11.0 79.5
Crank bearings, 1st stage1) ................................................................ 20 2.0 15
2nd stage1) ............................................................... through 90°
Flywheel (use new bolts) .................................................................... 70 7.0 51
Spark plugs (do not oil them!) .............................................................. 25±5 2.5±0.5 18
Camshaft gear ..................................................................................... 50 5.0 36
Intermediate gear ................................................................................ 50 5.0 36
Camshaft bearing cap ......................................................................... 20 2.0 15
Crankshaft, center bolt pulley, stage 1 ................................................ 60 6.0 43
stage 2 ................................................ Angle tighten through 60°

1)
Old bolts can be used provided the length does not exceed 55.5 mm (2.185").

19
 2. Special Tools

884359-1 Drift for the installation of the seal in the flywheel

housing

884596-8 Drift for the installation of the primary shaft in the

flywheel housing

884599-2 Drift for the installation of the seal in the flywheel

housing

884958-0 Drift for the changing of valve guides 251DOHC ,

AQ171

884959-0 Drift for the changing of valve guides 251DOHC,

AQ171

884960-6 Installation tool inlet valve seat 251DOHC, AQ171

884961-4 Installation tool exhaust valve seat 251DOHC,

AQ171

884966-3 Drift for the changing of valve guides 251DOHC,

AQ171

884967-1 Reamer valve guides 251DOHC, AQ171

884979-6 Cylinder head fixture 251DOHC, AQ171

885050-5 Stand fixture

20
9986052-0 Valve com-
pressor

9988452-0 Digital probe tester

9991426-9 Drift for the installation of support bearing in the fly-

wheel

9994090-0 Puller for support bearing in the flywheel

9995021-4 Press tool for the removal and assembly of the

camshaft, AQ131, AQ151, 230, 250

9995022-2 Tool for depressing valve depressors, AQ131,

AQ151, 230, 250

9995025-5 Installation tool for the intermediate shaft seal

9995026-3 Pair of pliers for adjustment shims AQ131, AQ151,

230, 250

Drift for the installation of valve guides (inlet),

9995027-1 AQ131, AQ151, 230, 250

21
 9995028-9 Drift for the installation of valve guides (exhaust),
AQ131, AQ151, 230, 250

9995029-7 Installation tool for valve seats (inlet), AQ131,

AQ151, 230, 250

9995034-7 Counterhold for the camshaft gear and intermediate

gear

9995220-2 Installation tool for valve seats (exhaust), AQ131,

AQ151, 230, 250

9995224-4 Reamer, valve guides AQ131, AQ151, 230, 250

9995276-4 Drift for the installation of sealing in the crankshaft

rear end

9995283-0 Removal tool for the crankshaft front seal

9995284-8 Counterhold for crankshaft pulley

9995309-3 Drift for the removal and installation of bushing in

the connecting rod

1159660-8 Tensioning tool for the toothed belt AQ171,

251DOHC

22
 3. Electrical System
General Generator
All engines have a single pole electrical system with The alternating current generator is a 14 V 50 A
an AC generator. The engine main wiring is fused VALEO. It is equipped with a charge sensor cable
with a thermic 40 A automatic fuse. (yellow) which is connected to the generator
(GEN) B+.
Ignition system
AQ131, AQ151, 230 and 250 have conventional
breaker point ignition systems. See the “Technical
Data” for the setting values. AQ171 and 251DOHC
are equipped with breakerless electronic ignition
systems. The ignition system memory unit has 63
optimal engine speed / ignition values programmed.
The ignition points for other engine speeds is
calculated based on these locked values.
Note! No ignition setting can be carried out on the
distributor. The ignition system has the correct set-
ting when all components are correctly installed. In
order to obtain exact installation there is a certain
amount of adjustment possible in the ignition setting
sender. All operation based adjustment is stopped.
All settings are permanently stored in the control
module and are stable because of the absence of
mechanicals (breaker points, mechanical ignition
setting). The only task of the distributor has is to In those cases where the generator is required to
distribute the current to the spark plugs via the rotor. charge several batteries (starter and operational bat-
teries) the charge sensor cable should be discon-
Instrumentation
nected from B+ and connected, using a 1.5 mm2 ex-
The engines were manufactured with two types of in- tension, to the accessory battery + terminal using a
strumentation. One earlier type 1 and the later type 2 double diode.
(for version refer to wiring diagrams). Both the in-
strumentation types are equipped with two 8 A fuses Minimum length of the brushes: 8 mm
for the system voltage (key switch in ignition posi- Resistance rotor winding 4,0–6,0 Ω
tion) and start voltage (key switch in start position). Resistance stator winding 0,11–0,15 Ω
Instrumentation type 2 is equipped with 2 connectors
for extra power outputs for accessories. One is
fused via the 8 A fuse for system voltage and has a
maximum permissible voltage output of 5 A (main
panel + any flying bridge panel). The other connector
has a maximum permissible voltage output of 20 A
and is not separately fused (power supply is via the
40 A automatic fuse for the main wiring). There is
also a connector for connecting instrument lighting
for extra instruments (a fuel gauge for example)
fused via the 8 A fuse for system voltage.
Starter motor
There are two versions. VALEO D6RA11 and
Hitachi S114-237.
Minimum length of the brushes:
VALEO = 14 mm
Hitachi = 12 mm.

23
Wiring Diagram AQ131, AQ151, 230, 250
With Instrument panel alternative 1

1. Oil pressure gauge

2. Temperature gauge, coolant
3. Voltmeter
4. Tachometer
5. Fuel gauge (alternative)
6. Instrument lighting
7. Key switch (B=30, S=50, I=15)
8. Switch, instrument lighting
9. Fuse 8 A
10. Fuse 8 A
11. Generator
12. Starter motor
13. Connector engine–instrumentation
14. Automatic fuse 40A
15. Main switch (option)
Cable colour code Cable cross sections 16. Battery
SB = Black AWG mm2 17. Temperature sensor
PU = Purple 18. Oil pressure sensor
16 1.5 19. Distributor
LBN = Light brown 13 2.5
R = Red 20. Ignition coil
10 6.0 21. Relay
GR = Grey 8 10.0
LBL = Light blue 22. Resistor
R/Y = Red/Yellow
BN = Brown
W = White
Y = Yellow

13

24
AQ131, AQ151, 230, 250 ALT. 1

25
Wiring Diagram 230, 250
With Instrument panel alternative 2

1. Tachometer
2. Oil pressure gauge
3. Temperature gauge, coolant
4. Voltmeter
5. Switch, instrument lighting
6. Instrument lighting
7. Key switch (B=30, S=50, I=15)
8. Fuse 8 A
9. Fuse 8 A
10. Contact terminal neutral position switch
(option/accessory)
11. Contact terminal safety switch (accessory)
12. Connector instrument lighting accessory
13. Connector power output, maximum 20 A
14. Connector power output, maximum 5 A
(main panel + flying bridge panel)
15. Connector, engine–instrumentation
16. Automatic fuse 40A
17. Main switch (option)
Cable colour code Cable cross sections 18. Battery
SB = Black AWG mm2 19. Temperature sensor
PU = Purple 16 1.5 20. Oil pressure sensor
LBN = Light brown 13 2.5 21. Distributor
R = Red 10 6.0 22. Ignition coil
GR = Grey 8 10.0 23. Starter motor
LBL = Light blue 24. Relay
R/Y = Red/Yellow 25. Generator
BN = Brown 26. Resistor
W = White
Y = Yellow

26
230, 250 ALT. 2

27
Wiring Diagram AQ171, 251DOHC
With Instrument panel alternative 1

1. Oil pressure gauge

2. Temp gauge
3. Voltmeter
4. Tachometer
5. Fuel gauge (alternative)
6. Instrument lights
7. Key switch (B = 30, S = 50, I = 15)
8. Switch, instrument lights
9. Fuse 8 Amp
10. Fuse 8 Amp
11. Alternator
12. Starter motor
13. Terminal block
14. Automatic fuse 40 Amp
15. Main switch (optional)
Cable colour code Cable cross sections 16. Battery (optional)
SB = Black AWG mm2 17. Temp sender
PU = Purple 18. Oil pressure sender
16 1.5
LBN = Light brown 19. Distributor
13 2.5
R = Red 20. Electronic ignition unit
10 6.0
GR = Grey 21. Relay
8 10.0
LBL = Light blue 22. Resistor
R/Y = Red/Yellow 23. Impulse sender, ignition unit
BN = Brown 24. Ground (screw)
W = White 25. Solenoid valve
Y = Yellow

13

28
AQ171, 251DOHC ALT. 1

29
Wiring Diagram 251DOHC
With Instrument panel alternative 2

1. Tachometer
2. Oil pressure gauge
3. Temperature gauge, coolant
4. Voltmeter
5. Switch, instrument lighting
6. Instrument lighting
7. Key switch (B=30, S=50, I=15)
8. Fuse 8 A
9. Fuse 8 A
10. Contact terminal neutral position switch
(option/accessory)
11. Contact terminal safety switch (accessory)
12. Connector instrument lighting accessory
13. Connector power output, maximum 20 A
14. Connector power output, maximum 5 A
(main panel + flying bridge panel)
15. Connector, engine–instrumentation
16. Automatic fuse 40A
Cable colour code Cable cross sections 17. Main switch (option)
SB = Black AWG mm2 18. Battery
PU = Purple 19. Temperature sensor
16 1.5 20. Oil pressure sensor
LBN = Light brown 13 2.5
R = Red 21. Distributor
10 6.0 22. Electronic ignition unit
GR = Grey 8 10.0
LBL = Light blue 23. Engine speed (RPM) sensor, ignition system
R/Y = Red/Yellow 24. Relay
BN = Brown 25. Starter motor
W = White 26. Generator
Y = Yellow 27. Ground terminal
28. Resistor
29. Solenoid valve, carburettor

30
251DOHC ALT. 2

31
 4A Cylinder Head
Trouble shooting and Remedies Fuel System
IMPORTANT! Always take the risk of fire into considera-
tion and therefore always keep a fire extinguisher near by!

Runs rough, the speed drops

Difficult to start, cold engine
Difficult to start, hot engine
Starts but stops again

Poor fuel economy

Weak acceleration
Runs rough at idle
Symptoms

Causes Backfires Action to be taken

Empty tank ............................. X X Fill the tank!
Closed fuel cock ..................... X X Open the fuel cock!
Clogged fuel filter ................... X X X X Clean the filter or replace the filter insert
Fuel pump not pumping .......... X X X X X Fuel pump diaphragm cracked. Replace it.
Fuel line blocked .................... X X X X Blow all lines clean
Carburetor overflowing ............ X X X Needle valve not closing. Float level wrong. Leaking float.
Adjust the level or replace the float.
Wrong idling setting ................ X X X X Adjust the idle accord. to “Technical Data”.
Wrong setting air screw .......... X X X X Set the screw and adjust till smooth running obtained
Clogged jets ........................... X X X Blow the jets. Never try to use hard objects in the jet holes.
Carburetor sucking additional air X X X X Tighten the carburetor and if necessary replace the gasket.
Check the throttle shaft clearance.
Intake manifold loose ............. X X X X Tighten the manifold and replace the gasket.
Acceleration jet clogged ......... X Blow the jet clean.
Throttle does not open ............ X X Adjust the throttle linkage
Wrong jet ................................ X X X Check the marking in “Technical Data”
Bad compression ................... X X X Take a compression test and then act according to results
Worn spark plugs ................... Change the spark plugs. See under “Technical Data”.
Wrong breaker points ............. Replace the breaker points and adjust dwell angle
Starting carburetor does not
work properly .......................... X X X Arm to be in closed position when the engine is hot
Wrong ignition setting ............. X X X Check setting with stroboscope and adjust if necessary
Toothed belt not installed
properly .................................. X X Check that the marking on the belt and gear wheel line up.
Adjust immediately!
Faulty acceleration pump ....... X X With engine stopped. Check by opening up the throttle and see if
fuel is spraying into the carburetor.

32
Overhauling and checking the
carburetor

3. Lift out the float and check it for leakage. Should

the float leak, the float level will not be correct. The
weight of the float should be 7,3 grams (0,26 oz’s).
Remove the emulsion jet (1) and the acceleration jet
(2).
NOTE! Don’t forget the gasket! Check and blow
clean with compressed air. Replace worn or dam-
aged parts if necessary!

1. Remove the carburetor from the intake manifold.

Notice the positioning of the plate in order to install it
in the same way. Take care of the plate. Remove
the screws (1) 4 pcs, and remove the top cover of
the carburetor.
NOTE! The carburetor on the model 230 (AQ131) is
equipped with a full speed jet (A), lower picture. This
jet is pressed into the top cover of the carburetor
and does not need to replaced unless damaged.

4. Remove the idle jet (1) and the main jet holder
(2). Remove the jet from its holder. Clean the jets
with compressed air. Replace if necessary. Remove
the mixture screw (3) and blow the channel clean.
The screw (4) is locking the venturi (5).

2. Remove the gasket (1) and needle valve (2).

Check to make sure that the needle valve does not
jam or that it’s worn (not sealing). Replace if neces-
sary.

33
 Early version Late version

5. Turn the throttle spindle (1) and press out the The Solex carburetor is available with earlier or later
thrust rod (2) from the lever (3). Then turn the thrust production versions of the butterfly valve housing.
rod downward and remove the check valve (4). Use The setting of the idle screws differs between the
compressed air to clean the check valve and the earlier and later versions according to the chart.
strainer. Wash the carburetor and use compressed Setting the idle screws (B):
air to clean its channels. Then install the check
valve and the strainer. Tighten the screw until it touches the carburetor le-
NOTE! Don’t forget the copper washer! Turn the ver. Then tighten further according to the chart.
throttle shaft and press in the thrust rod into the
lever.

Early version Late version

AQ131 2 2
230 – 2
AQ151 1½ 1
250 – 1
AQ171 1½ 1¼
251DOHC – 1¼

Setting of the idle mixture screws (A):

Bottom the screw lightly against the seat. Then back
it out according to the chart.

Early version Late version

AQ131 2 9½
230 – 9½
AQ151 2 8
6. Install the idle jet (1), the main jet (2) and the 250 – 8
mixture screw (3).
AQ171 2 10
NOTE! The copper washer on the main jet! Install
the emulsion jet (4), the acceleration jet (5) and the 251DOHC – 10
gasket (6). Put the float (7) into the float housing
and add a new gasket (8) and tighten the top cover
of the carburetor to the carburetor housing. Remove
the nut (9) and the levers to be able to replace the
spring (10).

34
 AQ131C, AQ131D earlier manufacture.

7. Install the intake manifold (if it has been re-

moved).
NOTE! Don’t forget the lifting eyelets (1) and the fuel
pipe bracket (2). Pull up the hose from the oil trap
through the opening in the intake manifold. Tighten-
ing torque for nuts and screws: 20 Nm (2.0 kpm/14.5
ft.lb). Tool width 12 mm.
Late version of AQ131C, AQ131D, 230 = the text
turned the right way up.

9. AQ131C, AQ131D, 230. These engines are

equipped with a new plate.
NOTE! The plate is located with the text “upside
down” (earlier manufacture). The plate is installed
between 2 gaskets. On engines of later manufacture
the text is turned the right way up.

8. AQ131A. Place a gasket on each side of the plate

and then onto the studs of the intake manifold.
IMPORTANT! Locate the plate the way the illustra-
tion indicates!

10. 250, AQ151C: Install the plate with a gasket on

each side.
NOTE! The plate for the front carburetor is marked
“FRONT” and consequently the rear one is marked
“REAR”. See the illustration!

35
11. AQ171A. Install the plate with a gasket on each
side of the plate on the front carburetor. Turn the
text correctly. See the illustration!
NOTE! There is no plate on the rear carburetor, only
a gasket is installed. 14. 250, 251DOHC (AQ151–171). Adjust and lock
the lever so that both throttle levers are activated
simultaneously.

12. AQ171C, 251DOHC. Install the plate with a gas-

ket on each side of it. Then place the plate along
with the gaskets on the front carburetor location of
the intake manifold.
NOTE! Turn the gasket in accordance with the illus-
tration.
15. 250, 251DOHC (AQ151–171). Adjust the position
IMPORTANT! There is no plate on the rear
of the swivel on the control cable so that the pins on
carburetor. Only a gasket is installed on the
the levers are located in the middle of the lever gaps
rear carburetor.
when connected. Tighten the swivel. Check while
test running that fuel flows out from both the carbu-
retors jets at the same time and that a “hissing/
sucking” sound can be heard from the carburetors.
Fine adjust if necessary.

13. Check that the idle and air screws are set as per
point 6. Then place the butterfly valve shaft between
the carburetors and fit them to the intake manifold. 16. Connect the fuel pipe to the fuel pump. Tool
230 (AQ131) does not have a separate butterfly width 12 mm.
valve shaft.

36
Cold start carburetor,
function.
Start with cold engine. Start with hot engine.
When starting, a vacuum is built up in the intake When the engine temperature is above 50°C (122°F)
manifold (1). This vacuum forces air to be sucked the shut-off valve (3) is closed. The vacuum in the
through the hoses (2) via a temperature controlled vacuum housing (4) ceases and the rod (6) returns,
shut-off valve (3). The vacuum which is formed in by spring pressure, to its original position.
the vacuum housing (4) affects the membrane (5) * If the engine speed is increased while the engine is cold,
which pulls the rod (6) so that the spindle (7) turns the vacuum in the vacuum housing is reduced and the
and opens a fuel and an air channel in the carbur- spring (8) presses back the rod (6) shutting off the extra
etor. This way the engine gets an additional fuel/air fuel/air supply.
supply.*

37
4B Renix Ignition System
Trouble-shooting and repair
ignition system 251DOHC,
AQ171

Ignition position sender

19. The crankshaft position sender is located at the
rear of the engine and registers the position of the
flywheel by reading the ‘teeth’ (machined holes) in
the circumference of the flywheel.

Description
17. The ‘Renix’ ignition system is a fully electronic
ignition system.
– Control unit with ignition coil
– Magnetic induction crankshaft position sender
– Specially machined flywheel
– Simple type of distributor

The distributor
20. The flat distributor is mounted at the rear of the
engine. The only task of the distributor is to deliver
the high voltage current to the correct spark plug.
The only internal part is the rotor.
NOTE! Timing adjustments cannot be made at the
distributor.

Control unit
18. The control unit consists of an electronic unit
with power amplifier. The ignition coil is of the mod-
ern dry type and is replaceable.

38
 The function
23. Half a turn before each explosion cycle the con-
trol unit is calculating a very exact pre-ignition going
out from the speed of the engine. There are 63 op-
timized engine speed values stored in the control
unit’s non-volatile memory. From these the control
unit selects a suitable ignition time.

The flywheel Speed Control

21. 40 holes are machined in the circumference of 24. In order not to damage the engine by over rev-
the flywheel. The space between the holes act as ving it there is an electronic function available which
teeth thus the flywheel can be regarded as a toothed reduces the dwell angle (the charging time of the ig-
wheel. nition coil) at 103.33 r/s (6200 rpm). The system
Since a 4 cylinder 4 stroke engine needs 2 sparks provides ignition but the output of the engine is so
per revolution, the toothed wheel is divided into two low that it cannot increase the engine speed.
halves. Each half has 20 teeth. Of these, 2 teeth in
each half turn are double the others in size. These
two big teeth are the reference points for the location
of the upper and lower ‘dead centers’. The points of
reference are located 90° before the upper and lower
‘dead centers’ respectively.

Signal Processing
22. The crankshaft position sender sends a signal
each time a tooth passes by. It also provides the
control unit with information when each of the 2 big
teeth pass by. Thus the position of the upper ‘dead
center’ is known since it is positioned 11 teeth after
the long tooth.

39
 WARNING! Ventilate the engine compartment
carefully and check that there is no smell of
gasoline or LPG-gas.

Trouble-shooting RENIX Tools

25. Control Unit

1 Tachometer connection
2 Ground connection
3 Feeding voltage (15+)
4 Firing position sender connection, red
5 Firing position sender connection, white 26. Use Volvo Penta digital test instrument
6 Is connected but not needed (speed control) 9988452-0 when fault-tracing the RENIX ignition
7 Not used (–3°) ground system.

8 Not used (+3°) ground

9 Ignition coil, primary winding
10 Ignition coil, primary winding
11 Ignition coil, secondary winding
12 Radio suppression connection

Trouble-shooting
A. The engine does not start (see para. 26 to 33).
B. The engine is running rough, starts with
difficulty, low output. (See para. 34 to 40).
C. The engine starts but does not continue to run.
(See para. 41 to 45).

40
Check the feed voltage Check the crankshaft position sender
27. Remove the plug ‘A’. Switch the ignition on. Con- 30. Remove plug ‘B’.
nect a voltmeter to check the voltage between ‘3’ - Measure the resistance of the ignition position sender
and ground. The voltage should be at least 9.5 Volts. between connections ‘4’ and ‘5’.
The resistance should be 190 Ohm ± 40 Ohm.
- Check that the wire at ‘4’ is red. Check that the wire at
Check the ground connection ‘5’ is white.
28. Measure the resistance between ‘2’ and ground. NOTE! Reversing these wires will change the timing ±4°.
The resistance should be 0 Ohm. The ground con-
nection is a bolt behind and below the alternator. - Check that the crankshaft position sender and the fly-
Should the resistance be higher than 0 Ohm. Check wheel are free from dirt.
the ground connection and the wire harness. - Should the resistance values be outside the tolerances:
replace the sender!

Checking spark plugs, ignition leads, the distrib-

utor and rotor.
29. Spark plugs: Part no 875820 (Bosch W6DC)
spark gap = 0.7 mm (0.02756"). Check to make sure
that the sleeve at the connection is properly tight-
ened.
- Ignition wires: Measure the resistance, should be
between 1 and 4 kOhm. Check connections for cor-
rosion. Check that the ignition wires are properly
connected to the spark plugs.
- Distributor: Check the resistance center connec-
tion high voltage 75 Ohm. Pins connection, 0 Ohm.
Check for corrosion, cracks and moisture.
- Rotor: Check the resistance. 1 kOhm, Check for
corrosion and cracks.
- Check the basic setting of the distributor on the en-
gine block. The ignition timing can not be altered at
the distributor.

Check the ignition coil

31. Remove the high voltage lead from the coil.
- Check that the contact points ‘9’ and ‘10’ are free
from corrosion.
- Measure the resistance of the secondary winding
between ‘9’ and ‘11’. Should be 4±1,5 kOhm.
- Measure the resistance of the primary winding be-
tween ‘9’ and ‘10’. Should be 0.6±0.2 Ohm.
- Should the resistance values be outside the toler-
ances: replace the ignition coil!

41
 Checking the setting of the crankshaft position
sender
38. Set the engine on T.D.C. for no 1 cylinder. In this
position the center of the iron core of the sender
should be positioned straight above the front edge of
the 11th ‘tooth’, (space between the holes), counted
back from the ‘long gap’. Should the sender not be at
this setting, then check to make certain that the en-
gine is really at T.D.C. For example, use a dial indic-
ator gauge through the spark plug hole.

Checking the control unit

32 A. - The ignition coil removed.
- Check that the contact points 9 and 10 are free
from corrosion.
- Measure the resistance between 3 and 9. The re-
sistance should be 0 Ohm. Checking the ignition
- Resistance higher than 0 Ohm: replace the unit. 39. Use a stroboscope to check the setting as fol-
lows:
B. - Install the plug connectors A and B. Switch on
the ignition. 14.17r/s (850 rpm) 10° ±2°
- Attach a 12 Volt test bulb, with a minimum rating of 25 r/s (1500 rpm) 14° ±2°
58.33 r/s (3500 rpm) 23° ±2°
4W, between 9 and 10.
75 r/s (4500 rpm) 24° ±2°
- Run the starter motor: the test bulb should start 91.67 r/s (5500 rpm) 31° ±2°
flashing. No flashing: replace the control unit.
33. Lubricate the connections A and B. Use part no Checking the speed limit
870806-2
40. Check (using a tachometer) that the engine’s
34. See paragraphs 26–27 speed does not increase above 6200±100 rpm.
35. See paragraphs 29 and 33. If the speed increases above 6200±100 rpm, then
36. See paragraph 30. the control unit must be replaced.

Checking the toothed belt against the

markings
41. Check that the timing belt is correctly installed
so that the markings correspond. See page 73.
42. See paragraphs 26–27
43. See paragraphs 29 and 33.
44. See paragraph 30.
37. Check that the tachometer is set properly for 4-
cylinder gas engines by turning the screw (A) to po- 45. See paragraph 38.
sition 3 and then to position 1.

42
Changing the rotor 251DOHC, AQ171

46. Remove the distributor cap, 3 screws. Tool

width: 8 mm.

47. Remove and replace the rotor. Re-install the dis-

tributor cap.

43
 4C Cylinder Head

Removal of the external

components

48. Remove the hose (1) from the oil trap and re- 51. Remove the bolts from the heat exchanger
move the intake cover. Tool width 10 mm. Take care bracket. Tool width: 12 mm.
of the flat washers and the spring washers.

49. Remove the flame arresters and the spark plug 52. Remove the screws from the thermostat housing
wires from the spark plugs. against the heat exchanger. Tool width: 12 mm.
NOTE! Take care of the spacer sleeves! (Not all
manufactures).

50. 251DOHC, AQ171. Remove the protective cover

over the camshaft gear wheels. Tool width: 10 mm.
53. Remove the hose clamp and pull off the cooling
water hose from the heat exchanger.

44
 57. Pull off the hose (1) from the carburetor and re-
move the screw holding the oil dipstick tube. Tool
width 1/2".
54. Pull the heat exchanger straight upwards from
the cooling water pipes and the cooling water hose.
Replace the O-ring on the heat exchanger and the
sealing rings on the cooling water pipes.

58. Remove the fuel pipe from the fuel pump. Tool
width: 12 mm.

55. Remove the cooling water pipe between the ex-

haust manifold and the oil cooler. Tool width: 10 mm.

59. 251DOHC, AQ171. Pull off the vacuum hoses

(1) from the intake manifold and the cold starting de-
56. Remove the exhaust manifold. Tool width: 13 vice as well as the connection (2) from the magnetic
mm. valve on the carburetor.

45
 63. Remove the sea water pump. Tool width: 10 mm.
60. Remove the intake manifold. Tool width: 12 mm.
The lifting eyelets are attached to the engine by the
upper and outer screws.
NOTE! It is only necessary to loosen the lower
screws a few turns only.

64. Remove the timing gear cover. Tool widths: Al-

len-key 6 mm and hexagonal 10 mm.
61. Remove the temp sender wire. Tool width 3/8".

65. Remove the alternator and the V-belt. Tool

62. Remove the cooling water pipes from the sea
widths: 13 and 16 mm.
water pump.

46
 belt and insert a 3 mm drill in the hole of the tension-
ing device. Then remove the belt.
NOTE! Do not turn either the crankshaft or the cam-
shaft while the belt is removed. The pistons can hit
the valves!

66. 251DOHC, AQ171.

IMPORTANT! Use the center bolt of the crank-
shaft to turn the crankshaft so that the mark-
ings on the toothed belt lines up with the mark-
ings of the camshaft gears and that of the
crankshaft as follows: 2 yellow lines against
the crankshaft marking (behind the pulley) and
1 line against each of the markings of the cam-
shaft gear. The marking of the pulley should
69. 251DOHC, AQ171. Remove the protective cover
line up with 0° on the timing gear casing.
for the spark plugs and remove the leads from the
spark plugs.

67. 251DOHC, AQ171. Loosen the Allen-head bolt

and turn the belt tensioning device in order to slack-
en the belt tension. Allen head key 8 mm. Remove
the belt.
70. 251DOHC, AQ171. Remove the distributor. Tool
IMPORTANT! Do not turn the crankshaft or width 10 mm. Pull the distributor off straight back-
the camshaft while the toothed belt is re- wards.
moved. The pistons can hit the valves! NOTE! Take care of the guide bushing (1).

68. 230, 250, AQ131, AQ151. Bring the engine to 71. Remove the thermostat housing and the thermo-
TDC as under paragr. 66. Then ease off the nut of stat. Tool width: 10 mm.
the belt tensioning roller. Tool width: 17 mm. Pull the

47
4D Cooling System
Overhauling the heat exchanger

75. Lift out the cooling element and the insulating

rubber mat from the housing. Pull the cooling ele-
ment straight upwards. If necessary use a screw-
72. Remove the front part of the heat exchanger. Al- driver to pry carefully. Clean all parts thoroughly.
len-key: 5 mm.

73. 250, AQ151. Remove the rubber gasket (1), the

pressure pad (2) and the hard rubber pad (3).
76. Remove the strainer housing and the tube con-
nection from the heat exchanger housing. Tool
width: 10 mm.

74. The only difference between the models 250,

251DOHC, AQ151, AQ171 is that the rubber pads on
250, AQ 151 have been replaced by a tension plate
(1) on model 251DOHC, AQ171. Otherwise the
same reconditioning method as for the heat ex-
changer applies.

77. Install new O-rings (1) on the strainer housing

and on the tube connection and install them on the
heat exchanger housing. Tool width: 10 mm.

48
78. Insert the rubber mat in the heat exchanger 82. Install the cover and tighten the screws in a
housing. criss-cross pattern, a little at the time.
NOTE! The cover will be pressed down approx-
imately 5 mm (0.25"). Allen key: 4 mm.

79. Put new seal rings on the cooling element.

Lubricate the seal rings with oil to facilitate the
installation of the element in the housing.

The sea water pump

83. Remove the cover on the sea water pump and
use pliers to pull out the impeller. Take care of the
key. Push out the seal ring. Install a new seal ring.
Turn the seal lip facing the impeller. Grease the seal
ring abundantly and carefully push the shaft into the
seal ring. Insert the key and install a new impeller.
Install the cover with a new gasket.
80. Center the cooling element carefully in the heat
exchanger housing and push it home. Make sure that
the rubber mat is properly clamped into its position.

The thermostat
84. When necessary check the opening temperature
of the thermostat by lowering it into warm water. It
should begin opening at a temperature of 82°C
(180°F). Can be fully open at 92°C (198°F). Check
81. Put the pressure pad, the hard rubber pad and to make sure that the rubber seal is in good condi-
the rubber gasket on the heat exchanger housing. tion.

49
4E Overhauling the valve system

230, 250, AQ131, AQ151

88. Remove the middle camshaft cap. Tool width:

1/2".

85. Remove the cylinder head. Tool width = 14 mm.

Remove the bolts in the sequence shown in the pic-
ture.
IMPORTANT! In order to avoid scratching the
cylinder head it should be placed on wooden
blocks.

89. Install special tool part no 9995021-4 on the

camshaft. Use the cap nut. The tool is keeping ten-
sion on the camshaft. Remove the remaining 4 cam-
shaft caps.

86. Remove the cylinder head gasket.

90. Remove the sealing (1) from the camshaft as

87. Remove the camshaft gear. Tool width: 17 mm. well as the plug in the opposite end. Back off the
Use counterhold part no 9995034-7. special tool, releasing the camshaft. Remove the
NOTE! Remove the washer behind the gear wheel. special tool and the camshaft.

50
91. Remove the valve tappets and keep them in the
same sequence as in the cylinder head.
95. Remove the valve seals from the guides of the
intake valves. Use a pair of pliers. Then remove the
lower washer (intake).

96. Clean the cylinder head and sealing surface.

Use a metal ruler and feeler gauge. The warp must
92. Remove the rubber seal from the valve stems. not exceed 0.5 mm (0.0197") lengthwise and 0.25
mm (0.0098") diagonally.
IMPORTANT! The cylinder head cannot be
machined if the warp is greater than 1.00 mm
(0.394") lengthwise or 0.5 mm (0.0197") diag-
onally.
Cylinder head height, new ...... 146.1 mm (5.75197")
Cylinder head height, min after
reworking ............................... 145.6 mm (5.73228")
Reworking, totally = 0.5 mm (0.01969")

93. Use valve spring compressor part no 9986052-0

to compress the valve springs.

97. Clean the valve seats with a cutter. Remove car-

bon deposits from combustion chambers and the
94. Remove the valve locks, retainers springs, the valves. The valve seats must not show signs of be-
lower washers (exhaust) and the valves. ing cracked nor any other type of damage. Should
NOTE! Make sure not to mix the parts! this be the case, they must be replaced.

51
98. Check the wear of the valve guides. Use new 101. Press in new valve guides. The cylinder head
valves and push up the valve 1–2 mm (0.03928– should be at room temperature. Use drift part no
0.07874") with the finger while the measurement is 9995027-1 for the intake and part no 9995028-9 for
taken. Clearance with a new valve and new valve the exhaust. Press the valve guides till the drift
guide, intake: 0.030–0.060 mm (0.00118–0.002362") touches the cylinder head. This gives the valve
and exhaust: 0.040–0.070 mm (0.0016–0.0028"). guide the correct height.
Maximum allowed clearance measured with new
valve and old valve guide is 0.15 mm (0.005906") for IMPORTANT! The pressing force must be at
intake as well as for exhaust. least 9000 N (900 kp) (2016 lbf). Should the
pressing force fall short the valve guide must
be removed again.

Changing the valve guide

99. Heat the cylinder head in water to a temperature

of 100°C (212°F) ± 10°C. Use a drift (part no
9995218-6) to press out the valve guides. Press the
valve guides in the direction of the combustion
chamber. Check to make sure that the valve guide
has not been subject to seizing.

102. Clean the valve guide internally. Use reamer

part no 9995224-4. Reamer part no 9995164 can
also be used.
NOTE! The valve and the seat must be lapped to-
gether after the valve guide has been replaced.

100. Valve guides in the standard size are available

as spare parts.

52
The valve seat

105. Knock out the valve seat with a long drift

through intake port the cylinder head.

103.
IMPORTANT! Always replace the valve guides
prior to removing the valve seat.
Grind two recesses in the old valve seat ring. These
recesses will reduce the tension in the seat ring.
Then grind a cut in the seat ring (in order to provide
a hold for the chisel) Make sure not to damage the
cylinder head!

106. Check the position of the valve seat. Should the

seat location be damaged, it has to be reamed
(milled) to the closest oversize. Then measure the
valve seat diameter. Use an internal micrometer.

104. Crack the valve seat with a chisel. Use the

chisel with extreme caution.

53
 Stellite
109.
IMPORTANT! The exhaust valves are ‘Stellite’-
coated and must not be reworked! They must
only be lapped to seal against the valve seat
107. Find a valve seat with the correct dimension.
using grinding compound. In case they are re-
The valve seats are not marked but have to be
worked, the ‘Stellite’ coating is removed and
measured. The valve seats must be 0.17 mm
thus the valves lose part of their heat protec-
(0.00669") bigger than the cylinder head location.
tion.
Should the grip fit be less than 0.17 mm (0.00669")
the seat location must be reamed to the closest (0.051–0.075") (0.067–0.091")
oversize. Use a valve seat cutter.
Valve seat, diameter: Intake: Exhaust:
Standard, mm 46.00 38.00
(inches) (1.811") (1.496")
Oversize 2, mm 46.50 38.50
(inches) (1.83") (1.5157")

Intake Exhaust

110. Mill or ream the valve seats. The same angle

for intake as for exhaust. The valve seat width, see
the picture. Check the contact pattern of the valves
against the seats. If necessary use grinding com-
pound to grind the valves against the seats.

108. Heat the cylinder head in water to a tempera-

ture of approx. 100°C (212°F). Put the new valve
seat on installation drift part no 9995029-7 (for the
intake seat) and part no 9995220-2 (for the exhaust
seat). Cool the valve seat to a temperature of –70°C
(–94°F) by using carbon dioxide snow (dry ice) or its
equivalent. Use protective gloves! Install the valve
seat in the cylinder head. This sequence must be
done quickly and at least within 3 to 4 seconds.
This depends on the fact that the components must
have their predetermined temperature at the time of 111. Put the camshaft in the cylinder head. Install
assembly. Then check the fit of the seat. The seat the rear cap. Move the camshaft to and fro. The
should be fully home and held in position. Should the clearance should be 0.1–0.4 mm (0.00394–0.0157").
seat not be held in position, a seat with bigger di- Measure the clearance with a feeler gauge. In case
mensions must be installed. the clearance is too big, the cap must be replaced.
NOTE! After having replaced the seat it must be Measure the clearance again. When the correct
milled and the valve lapped to seal. clearance has been obtained, remove the camshaft.

54
112. Check the valve springs in a spring tester.
Length, unloaded ............................... 45 mm (1.77")
loaded 305±20N (67.2±4.48 lbf.) ....... 38 mm (1.50")
loaded 765±40N (170±8.96 lbf.) ........ 27 mm (1.06") 115. Check that the clearance of the adjustment
washer in the valve tappet is not too big. If there are
wear marks on the flat surface, it should be re-
placed. The clearance between the adjustment
washer and the valve tappet should be 0.009–0.068
mm (0.000354–0.00268")

113. Check the valve tappets for scratches and

other visible damage.

116. Place the valve tappets in the cylinder head

and check that the clearance is not too big or that
they seize.
NOTE! Do not mix the tappets. Put them in the
same position as prior to the check. Clearance:
valve tappet – cylinder head: 0.030–0.075 mm
(0.001118–0.002953")

114. Check that the valves and valve seats are

lapped perfectly by coating the chamfer of the valve
discs with marking dye and then rotating them with
light pressure against the valve seats. If the marking
dye is not evenly distributed on the whole chamfered
surface of the valve seat (the valve does not seat)
the valve must be reground and checked until a
completely satisfactory result has been obtained.

55
Assembling the cylinder head

117. Check to make sure that the distance between 120. Oil and install the valve tappets along with the
the valve lock and end of the valve stem is at least adjustment washers and in the same location as
3.5 mm (0.1378"). earlier.

121. Oil the bearing halves, the camshaft lobes, the

118. Place the valve spring seal in the cylinder valve tappets and the adjustment washers and insert
head. Oil and install the valve. Install the seal. Only the camshaft. The guide pin for the toothed belt
the intake valves have a valve stem seal! wheel should be turned facing upwards.

119. Install:
1. The valve spring.
2. The valve spring retainer.
3. The valve lock.
4. The rubber seal. 122. Coat the sealing surface of the rear camshaft
bearing cap against the cylinder head with a gasket
Use a valve spring compressor. Then install the
compound. Put the rear bearing cap (the axial bear-
spark plugs.
ing) and the rubber sealing in its location. Install the
NOTE! Make sure that the spark plug thread enters
2 nuts but without tightening them.
properly in order not to damage the cylinder head
thread. Tightening torque: 25–30 Nm (2.5–3.0 kpm/
18–22 ft.lbs).

56
 126. Oil and tighten the last bearing cap. Now tight-
123. Install special tool part no 9995021-4 and press en all the nuts with a torque wrench. Tightening
down the camshaft. torque: 20 Nm (2.0 kpm/15 ft.lbs).

124. Lubricate the rubber lip of the camshaft sealing

and install it on the camshaft. Make sure not to dam-
age the rubber lip by the edge of the camshaft during
the assembly.
NOTE! Install the sealing ring so that a new sealing 127. Install the camshaft gear wheel and the spacer
surface against the camshaft is obtained. washer. Use counterhold part no 9995034-7.
Tightening torque: 50 Nm (5.0 kpm/36 ft.lbs).

125. Oil and install the remaining 3 bearing caps. In- 128. Check the belt tensioning device. The bearing
stall the nuts but without tightening them. should be free from play. Should the contact surface
NOTE! Coat the contact surface of the front bearing of the roller be damaged, the roller and the toothed
cap against the cylinder head with a gasket com- belt must be replaced.
pound. Make sure that the sealing is properly Compress the spring and lock it with a 3 mm drill
aligned prior to the tightening of the front bearing and then install the belt tensioning device on the cyl-
cap. Then remove the special tool. inder block.

57
 132.
IMPORTANT! Do not turn either the crank-
shaft for the camshaft. The pistons can now
hit the valves!
Replace the cylinder head bolts in case they show
129. Set the piston for cylinder no 1 at T.D.C. Check
signs of elongation. If a bolt is elongated or not can
to make sure that the contact surface of the engine
be determined by checking the ‘waist’ of the bolt. If
block is properly cleaned and install a new cylinder
the bolt is elongated the waist of the bolt is
head gasket
stretched. It is allowed to re-use the bolts a maxi-
mum of 5 times. In case of uncertainty, always re-
place the bolts with new ones.

133. Oil the threads of the cylinder head bolts and

install them. Tighten the cylinder head bolts in se-
quence and in 3 steps.
1 = 20 Nm (2.0 kpm/15 ft.lbs)
2 = 40 Nm (4.0 kpm/30 ft.lbs)
3 = angle tightening 120°.

130. Set the camshaft in position T.D.C. for cylinder

no 1.

131. Install the cylinder head.

58
Adjusting the valves 230, 250,
AQ131, AQ151

134. Measure the valve clearance for the number 1 137. Use special tool part no 9995026-3 (pair of pli-
cylinder, using a feeler gauge. ers) to lift out the washer.
Clearance, cold engine: 0.35–0.40 mm (0.01378–0.01575")
Clearance, hot engine: 0.40–0.45 mm (0.01575–0.01772")
The same clearance for intake as for exhaust valves.
NOTE! Should the clearance when checking be between
the values given below, adjustment is not necessary.
Cold engine: 0.30–0.40 mm (0.0118–0.01575")
Hot engine: 0.35–0.45 mm (0.01378–0.01772")

138. Measure the thickness of the washer with a mi-

crometer. Calculate the thickness of the washer,
giving the correct clearance.
Example: The measured clearance is: 0.30 mm
(0.0118"), the correct clearance is 0.40 mm
135. When necessary the adjustment washers are to (0.01575"), thus a difference of -0.10 mm (0.00394").
be replaced as follows: Turn the valve tappet so that Measured thickness of existing washer: 3.80 mm
the grooves are aligned 90° to the length of the cam- (0.1496").
shaft. The correct thickness on a new washer: 3.80–0.10 =
3.70 mm (0.1496–0.003294" = 0.14567").

139. The washers are available in thicknesses be-

136. Install special tool part no 9995022-2 and press tween 3.30 (0.12992") and 4.5 mm (0.17717") at in-
down the valve tappets. Tighten the tool spindle and tervals of 0.05 mm (0.00197"). Always use new
adjust until the groove of the valve lifter is above the washers only. See page 60.
edge and thus accessible with a pair of pliers.

59
140. Oil the new washer and insert it with the mark- 141. Remove the tool part no 9995022-2. Turn the
ing facing downwards. camshaft in position for ignition of number 3 cylinder
to fire. Measure the clearance with a feeler gauge
and remedy if necessary in accordance with the
above instructions. Repeat the procedure on number
4 and number 2 cylinders and in this order. Then
turn the camshaft a couple of turns and check the
clearances for all the valves.

Valve Adjustment Kit for 230,

250, AQ131, AQ151
Kit No 884516-4
The kit contains a shim assortment to provide as
large an adjustment range as possible. It can be
complemented if necessary by ordering from the
Volvo Penta Parts Department. The complete kit,
part no 884516-4 contains the following parts:

Part No: Qty: Designation: Thickness mm (inch)

463551 6 Adjustment shim 3.55 (0.13976")
463552 6 Adjustment shim 3.60 (0.14173")
463553 6 Adjustment shim 3.65 (0.14370")
463554 6 Adjustment shim 3.70 (0.14567")
463555 6 Adjustment shim 3.75 (0.14764")
463556 12 Adjustment shim 3.80 (0.14960")
463557 12 Adjustment shim 3.85 (0.15157")
463558 12 Adjustment shim 3.90 (0.15354")
463559 12 Adjustment shim 3.95 (0.15551")
463560 6 Adjustment shim 4.00 (0.15748")
463561 6 Adjustment shim 4.05 (0.15945")
463562 6 Adjustment shim 4.10 (0.16142")
463563 6 Adjustment shim 4.15 (0.16339")
463564 6 Adjustment shim 4.20 (0.16535")
834557 1 Index
834613 1 Tool box
9995022 1 Depressing tool
9995026 1 Pair of pliers

60
Overhauling the valve system
251DOHC, AQ171
Technical Description

The camshafts are fitted in a special camshaft carri-

er fitted on the cylinder head. The seal between the
camshaft carrier and the cylinder head is done in
two ways. The spark plug wells are sealed by four
The engine has double overhead camshafts which O-rings between the camshaft carrier and cylinder
open and close the valves via hydraulic valve tap- head. The sealing of the flat surfaces between the
pets. The hydraulic valve tappets are filled with oil camcylinder head is done using a sealing compound
and are self-adjusting. The valve guides have a 19° (Loctite).
angle to the cylinder head. The valve cover gasket is in two parts. One seals
against the spark plug wells while the second part
seals between the camshaft carrier and valve cover
outer boarder.
Piston
Groove
Check valve

4 valves per cylinder

Spring
With two inlet and exhaust valves, the total valve
area has increased by approx. 50% compared with
the 230 and 250 (AQ131, AQ151). This improves the Tappet cylinder
gas flow to the combustion chamber and the fuel/air
mixture is burnt more effectively.
Hydraulic valve tappets
Between the camshaft and the hydraulic valve tap-
pet there is normally a certain clearance. The clear-
ance is greater when the engine is cold than when it
is hot to allow for the lengthwise expansion of the

61
valve. A certain clearance is also required to ensure
that the valve does not remain partly open, allowing
combustion gases to pass and the valve to be dam-
aged. Preferably, the clearance should be as close
to zero as possible. This is possible with hydraulic
valve tappets.
The solution chosen for the 251DOHC, AQ171 is a
spring inside the valve tappet cylinder which holds
the valve tappet against the camshaft, but at a lower
pressure than the valve spring, to allow the valve to
expand lengthwise.
A check valve (ball) prevents oil from being pressed
out when the camshaft pushes the hydraulic valve The camshaft presses the valve tappet down
tappet and the oil pressure in the valve tappet cylin-
The oil pressure in the valve tappet cylinder then be-
der is greater than the engine’s oil pressure.
comes greater than the engine’s, the check valve
When a valve is pushed down with the engine closes and the hydraulic valve tappet works as one
stopped, oil will gradually leak out from the hydraulic unit.
valve tappet and the valve clearance will be greater
when the engine is started and until the oil pressure
has been built up. The distance between hydraulic
valve tappet cylinder and the piston is therefore cho-
sen to ensure mechanical safety.

The valve tappet back on the camshaft’s base

circle
The engine’s oil pressure is greater than the oil
pressure in the valve tappet cylinder, the check
valve opens and lets in pressure oil so that the valve
tappet is pressed against the camshaft.

Fault-tracing valve tappets

The valve tappets are very reliable and faults are
very rare. If the tappets are noisy, the cause is usu-
ally too high or too low oil level. Check the oil level!
Momentary noise may be heard when the engine is
The hydraulic valve tappet on the camshaft’s started. This is normal and is due to the oil being
base circle drained from the tappets when the engine has been
The oil for the tappets comes from the camshaft car- stopped for a period. The tappets are refilled with oil
rier and is pressed into the valve tappet via a groove a few seconds after starting.
and a hole in the side of the tappet. Oil passes Noise at high engine speed, but quiet at low
through the slit in the top of the valve tappet and into speed: Oil level above max on the oil dipstick – the
the piston. As the engine’s oil pressure is greater crankshaft whips the oil to foam, which causes the
than the oil pressure in the hydraulic valve tappet, noise in the tappets. Too low oil level – the oil pump
the oil passes the check valve (the ball). sucks air at high engine speed or when the boat
rolls. Air in the oil can cause noise in the tappets.
Spontaneous noise at idling, disappears with in-
creased engine speed: This is an indication of worn
valve ball or dirt in the tappets. Noise at idling or
when engine oil is hot, quiet at higher engine
speed or with cold engine oil: Tappets that leak a
lot of oil.

62
Overhauling the valve System
251DOHC, AQ171
IMPORTANT! Do not turn either the crank-
shaft or the camshaft. The pistons can hit
the valves!

146. Lift out the hydraulic valve tappets and place

142. Remove the nuts and the valve cover. Tool
them upside down in an oil bath. Use a magnet or
width: 10 mm. Remove the gaskets.
suction cup as an aid when lifting out of the valve
tappets.
NOTE! Be careful to place the tappets in the order
they had in the engine. The tappets must be fitted in
their respective bores. Do not mix them! Mark the oil
bath vessel to ensure that the correct order is main-
tained.

143. Remove the camshaft bearing caps. Tool width:

1/2". The caps are numbered from 1 to 10.
NOTE! Number 10 is marked with a ‘zero’ only. The
caps numbers 1 to 5 are installed on the port cam-
shaft, counted from the number 1 cylinder.

146A. Check the valve tappets for any wear. Meas-

ure if necessary.
Hydraulic valve lifter, measurement
144. Lift out the camshaft and remove the camshaft A: External diameter, mm/in ....................... 35/1.378
gear wheel. Use special tool part no 9995034-7 as B: External height, mm/in ............................ 26/1.024
counterhold. Tool width: 17 mm. Distance to top of valve tappet
C (1): Unloaded, mm/in .......................... 18.40/0.724
C (2): Compressed, mm/in .................... 16.15/0.636

145. Remove the sealing rings (1). Check the cam-

shafts for wear. Replace them if necessary.

63
 150. Remove and place the valve locks (1), retainer
(2), spring (3) and the lower washer (4) (exhaust)
147. Remove the 5 nuts which attach the camshaft
and the valve (5) in the same sequence as removed
carrier to the cylinder head. Tool width: 1/2". Then
from the engine.
lift out the camshaft carrier.
NOTE! Do not mix the parts!
NOTE! Remove the O-rings between the cylinder
head and the camshaft carrier (later production).

148. Remove the cylinder head by removing the cy-

linder head bolts in the sequence shown in the illus-
tration. Spanner width: 14 mm. Then remove the cy-
linder head gasket.
151. Remove the valve seals from the intake valves
IMPORTANT! The cylinder head is made of and then the lower washer.
aluminum. In order to avoid scratches etc,
place the cylinder head on wooden blocks.

152. Clean the cylinder head and sealing surface.

Use a metal ruler and a feeler gauge. The warp must
not exceed 0.5 mm (0.0197") lengthwise and 0.25
mm (0.0098") diagonally.
IMPORTANT! The cylinder head cannot be
machined if the warp is greater than 1.0 mm
(0.0394") lengthwise or 0.5 mm (0.0197") diag-
onally.
Cylinder head height, new ............. 103.5 mm (4.0748")
149. Remove the valves. Use special tool, part no Cylinder head height, min after reworking ..... 103.0 mm
9986052-0. (4.055")
Reworking, total = 0.5 mm (0.0198")

64
 Changing the valve guides

153. Use a cutter to clean the valve seats. Remove 155. Place the cylinder head in special tool part no
carbon deposits from the combustion chambers and 884979-6 and hold it with 2 screws (M12).
the valves. Check the valves for cracks and other
possible damages. Replace if necessary.

156. Use special tool part no 884959-0 to start

pressing out the valve guide. Press until the tool bot-
toms.

154. Check the wear in the valve guides. Use new

valves and push up the valves 1–2 mm (0.0394–
0.0787"), hold while measuring. Clearance with new
valve and new valve guide, intake: 0.030–0.060 mm
(0.00118–0.00236"), exhaust: 0.040–0.070 mm
(0.00157–0.00276"). Maximum clearance allowed
with new valve and old valve guide is 0.15 mm
(0.0059") for intake as well as for exhaust.

157. Change over to special tool part no 884958-0

and press until the tool bottoms.

65
 Changing the valve seat
The valve seats should, in principle, be changed in
accordance with paragraphs 103–108 on pages 53
and 54. Special tool part no 884960-6 for intake and
part no 884961-4 for exhaust.
158. Put the new valve guide on special tool part no
884966-3.

Stellite

161.

IMPORTANT! The exhaust valves are ‘Stellite’

159. Press the new valve guide into the cylinder
coated and therefore cannot be machined.
head. Press home the tool.
NOTE! The old valve guide is still in the cylinder They can only be lapped to fit by using grinding
head and is ‘guiding’ the tool with the new valve compound. If they are machined the ‘Stellite’-coating
guide. The old valve guide will fall out of the cylinder is removed and the heat protection of the valve is
head. reduced.

(0.051–0.075") (0.067–0.091")

Inlet Exhaust

160. Ream the valve guide. Use special tool part no

162. Machine the valve seats. The same angle for
884967-1.
intake as for exhaust. The valve seat width = ac-
NOTE! New valve must always be lapped against
cordance with the illustration. Check the valve con-
the valve seat.
tact against the seat. If necessary lap the valves us-
ing grinding compound.

66
 Assembling the cylinder head

163. Check the valve springs with a spring tester.

Length, unloaded ............................... 43 mm (1.6929")
loaded 232 N ± 20 N (51±4.48 lbf.) ..... 37 mm (1.4567")
loaded 640 N ± 40 N (141±8.96 lbf.) 26.5 mm (1.0816")

165. Place the lower valve spring washer in the cy-

linder head. Oil and install the valve. Then install the
seal on the intake valves only.

164. Check to make sure that valves and valve

seats are seating correctly by coating the seat sur-
face of the valve with marking dye and turn it with
light pressure against the valve seat. Should the
marking dye not be evenly distributed against the
seat contact surface (the valve will not seal), the
valve has to be lapped further and checked once
more until a correct result has been obtained.

166. Install:
1. The valve spring
2. The upper valve spring retainer
3. The valve lock
Use the valve spring compressor.
NOTE! Install the exhaust valves without seals.
Then install the spark plugs.
NOTE! Make sure that the spark plug thread enters
properly in order not to destroy the thread in the alu-
minum cylinder head. Tightening torque: 25–30 Nm
(2.5–3.0 kpm/18–32 ft.lbs).

67
Assembly

171. Tighten the bolts in sequence and in steps. See

the illustration. Tool width: 14 mm.
1 = 20 Nm (2.0 kpm/15 ft.lbs)
2 = 40 Nm (4.0 kpm/30 ft.lbs)
3 = angle tightening through 120°.

167. Check to make sure that the number 1 piston is

at T.D.C., with the pulley at 0°.

168. Check that the block and cylinder head contact

surfaces are properly cleaned. Install a new cylinder 172. Place the O-rings in their positions on the cylin-
head gasket and then install the cylinder head. der head.
Check to make sure that the gasket between the NOTE! On engines of earlier make, there are no O-
cylinder head and the water circulation pump is not rings.
damaged and correctly positioned.

Sealant for the camshaft carrier

169. Install the cylinder head bolts in the cylinder head.

NOTE! The 3 short ones are to be positioned on the 173A. Use trichloroethylene or an alkaline degreas-
port side and between the front and rearmost bolts. ing agent to clean the components carefully. Follow
They are marked ‘white’ in the illustration. the instructions for the cleaning agent carefully.
Coat the contact surface of the camshaft mechan-
ism with a thin layer of sealant (approx 0.05–0.10
mm 0.00197–0.00394"). Use ‘Loctite 518’ or its
equivalent.
170. The cylinder head bolts must be replaced in NOTE! Use a short fiber type of roller or a brush to
case they show signs of elongation. Whether a bolt apply the sealant.
is elongated or not can be seen on the waist of the
bolt. If the waist is elongated, then the bolt has to be IMPORTANT! Make sure that no sealant en-
replaced by a new one. The bolts can be re-used 5 ters the oil channels (1) or the drain channel
times at the most. If uncertain, replace all bolts. (2).

68
 176. Grease the seal ring and install it carefully on
173B. Place the camshaft carrier on the cylinder the camshaft.
head. Install the 5 nuts by hand. Make sure the car- NOTE! Turn the ‘smooth’ side facing outwards (to-
rier enters the end guides. wards the front).

174. Place the hydraulic lifters in their exact previ-

ous locations.
NOTE! Should any of the valve lifters be worn (do 177. Install the camshaft gears on the camshaft.
not function), it has to be replaced as a unit. Lower Use counterhold, part no 9995034-7. Tightening
the lifter in clean oil and pump with the center plug torque: 50 Nm (5.0 kpm/36 ft.lbs).
until it feels ‘hard’.

178. Place the camshafts in the camshaft carriers

so that the front lobes (No 1) are turned facing up-
ward and inward towards each other.
NOTE! The camshaft with a groove for the distrib-
utor drive, should be installed on the port side.
Check to make sure that the markings on the cam-
shaft gears are pointing up.
175. Check to make sure that the half-moon seal in
the camshaft carrier is not damaged. Replace if ne-
cessary.

69
179. Place the camshaft bearing caps 1 to 5 on the 181. Install new gaskets on the camshaft carrier.
port camshaft. The gasket in the middle of the picture can be in-
NOTE! Caps no’s 1, 5 and 6 should be coated with stalled in one way only. The arrow (1) should point
gasket compound. Then place the bearing caps no’s at no 1 cylinder.
6 to 10 on the starboard camshaft. The number 10
bearing cap is marked with a ‘zero’ only.
IMPORTANT! Make sure that the sealing rings
at caps no’s 1 and 6 are properly positioned.
IMPORTANT! Do not turn the crankshaft or
the camshaft. The pistons will hit the valves.

182. Install the valve cover and tighten it with the

nuts. Tool width: 10 mm.

180. Install the nuts and tighten them with a torque

of 20 Nm (2.0 kpm/15 ft. lbs). Tool width: 1/2".
Tighten alternatingly and in sequence.
NOTE! Also tighten the nuts in the middle.
IMPORTANT! Do not turn the crankshaft or the
camshaft! The pistons might hit the valves!

70
4F Installing the toothed belt

Installing the toothed belt 230, 250,

AQ131, AQ151

185. Place the valve cover without the gasket on the

cylinder head. Position the marked plate on the two
front stud bolts. Then make sure that the marking of
the camshaft gear lines up with the plate marking.
Note! not all engines have the marked plate.

183. Check to make sure that the recess (1) of the

outer guide plate coincides with the marking of the
housing.

186. Check the condition of the toothed belt.

NOTE! Grease or oil must not be on the belt. Then
adjust the markings of the belt as follows: Two lines
184. Align the intermediate shaft with the marking against the marking of the crankshaft guide plate
(1). and one line against the marking of the intermediate
wheel. The last marking, also one line, against the
marking of the camshaft gear.
NOTE! At the crankshaft marking, the belt must be
pushed down into the correct tooth gap for checking.

71
 189. Turn the crankshaft clockwise a few degrees.
This is in order to remove the ‘slack’ between the
187. Carefully move the belt onto the belt tensioning belt wheels.
roller being careful not to damage the belt. NOTE! Do not turn the crankshaft anti-clockwise.
This will cause the belt to jump over giving an incor-
rect setting.

188. Make sure that the nut of the belt tensioner is 190. Back off the nut of the belt tensioner again to
not tightened. Compress the tensioner and remove allow the spring to tension the belt again. Make sure
the drill (or other tool) to allow the spring to tension that the belt tensioner is not seized in its pivot.
the belt. Tighten the nut. Torque the nut 50 Nm (5.0 kpm/36 ft.lbs). The belt
must be tensioned at least once per season and re-
placed every 500 hours of operation. Remove the
valve cover and install the valve cover gasket.

72
Installing the toothed belt 251DOHC,
AQ171

193. Turn the belt tensioner to tension the belt and

then tighten the Allen-head screw. Tool width: 8 mm.
The belt must be tensioned at least once per season
and be replaced after every 500 hours of operation.

191. Inspect the belt tensioner. There should be no

play in the bearing. If the contact surface of the roll-
er is damaged, the roller and the belt must be re-
placed. Fine-adjust the camshaft gears and the
crankshaft gear so that they will line up exactly with
the respective markings on the valve cover and the
seal holder behind the torsional damper.
194. Method 1: Correct belt tension. Turn the crank-
shaft a few degrees counter clockwise and check
that the marking on the belt (2 lines) coincide with
the marking on the guide plate. Then turn the crank-
shaft a few turns clockwise. Take the belt between
the index finger and the thumb and twist it. It should
be possible to twist the belt 90° by hand. Increase or
decrease the belt tension, should the belt not be ten-
sioned correctly.

192. Install the belt so that the yellow (lines) mark-

ings align as follows:
2 lines against the crankshaft gear marking and 1
line against each of the camshaft gear markings. For
the crankshaft gear marking, the belt has to be de-
pressed somewhat into the correct tooth gap for
checking. Also see under 250, AQ151).
NOTE! For the 250, AQ151 the belt must be in-
stalled on the belt tensioner prior to being installed
on the camshaft gears, this because the belt ten-
sioner is provided with guiding edges.
Check carefully that the belt is installed so that the
195. Method 2: Tension the belt and place special
markings line up.
tool part no 1159660-8 on the belt. ‘Zero’ the instru-
NOTE! It is not necessary to adjust the marking of
ment by depressing the lever (1). Then press the
the intermediate wheel against the belt marking.
tool against the belt until a ‘click’ is heard. Note the
value of the tool. The correct value should be 20 to
25 Kilos (44–55 lbs). Tension or loosen the belt as
required.

73
4G Installing the external
components of the Cylinder Head

199. Install the V-belt and tension it to allow it to be

depressed approx. 5 mm (0.2") by normal thumb
pressure. Tool width: 1/2" and 16 mm.
NOTE! Make sure the V-belt enters the correct
groove on the crankshaft pulley.

196. Install the timing gear cover. Tool width: Allen-

head 6 mm and hexagonal 10 mm.

200. Install the thermostat along with a new gasket

197. Install the sea water pump. Tool width: 10 mm. in the thermostat housing. Then install the thermo-
Make sure that the pump shaft engages the cross- stat housing on the engine. Tool width: 10 mm.
piece carrier.

201. 251DOHC, AQ171. Make sure that the O-rings

on the distributor are not damaged. Replace if ne-
cessary. Grease the distributor shaft and install the
198. Install the cooling water pipes on the sea water distributor on the engine. Tool width: 10 mm.
pump. Check the seal. Replace if necessary.
IMPORTANT: In order to position the distrib-
utor correctly, the plastic bushing (1) must be
installed with the screw (2).

74
202. 251DOHC, AQ171. Install the spark plug leads
on the spark plugs and push them into the lead hold-
ers.

206. Install the intake manifold together with the car-

buretor. Tighten the oil dipstick tube to the intake
manifold. Tool width: 1/2" or 13 mm. Then install the
hose between the fuel pump and the carburetor.

203. 251DOHC, AQ171. Install the protective cover

for the spark plugs.

207. 251DOHC, AQ171. Install the vacuum hoses

204. Put on a new gasket for the intake manifold on (1) from the intake manifold and the cold starting de-
the cylinder head. Tighten the lower bolts slightly. vice and the connection (2) on the magnetic valve
on the carburetor.

208. Install the rubber seals, the flame arrestors and

the covers on the carburetors.

205. Make sure that the temp sender wire is not

damaged and push on the protective cap.

75
209. Install the frame arrester cover. Tool width: 10
mm.
212. Install the pipe between the oil cooler and the
exhaust manifold. Tool width: 10 mm. Check the
sealings. Replace if necessary.

210. Connect the hose from the oil trap to the under- 213. Put new sealings on the cooling water pipes
side of the flame arrester. and a new O-ring on the heat exchanger and install
the heat exchanger to the pipes. Assemble the heat
exchanger to the thermostat housing. Tool width: 12
mm.

211. Install the exhaust manifold with a new gasket.

Tool width: 1/2" or 13 mm.
NOTE! The gasket will only fit one way. The 2 short
bolts to be installed up front. 214. Install the heat exchanger on the exhaust mani-
fold. Tool width: 12 mm.

76
215. Install the cooling water hose on the heat ex- 216. 251DOHC, AQ171. Install the protective cover
changer. Tighten the hose clamp properly. over the toothed belt/camshaft gear wheels. Tool
width: 10 mm.

77
 5 The Cylinder Block

5A Removing the external

components

217. Remove the oil dipstick, oil dipstick tube, 220. Remove the starter motor. Tool width: 19 mm.
alternator and the cooling water pipe. Tool width for
alternator wires: 10 and 18 mm.

218. Remove the distributor. Tool width: 13 mm and

the fuel pump, Allen-head key 6 mm.
221. Remove the coolant circulation pump. Tool
width: 10 mm. If the pump has been damaged, the
pump must be replaced as a unit, except for the pul-
ley which can be re-used.

219. Remove the control bracket, ignition coil and

the oil trap. Tool width: 13 mm.
222. Remove the oil filter. Watch out for oil spillage!

78
 225. Remove the drain cock. Tool width: 18 mm.
Clean and flush the cooling water jackets properly.
223. Remove the wire from the oil pressure sender.

224. Remove the big nut on the oil cooler. Tool

width: 29 mm. Then separate the cooling water
tubes from the oil cooler and remove from the en-
gine.

79
5B Overhauling the Crank
Assembly

229. Remove the belt wheel and the inner guide

plate from the crankshaft. Make sure not to damage
the teeth of the belt wheel.

226. Remove the flywheel housing as well as the

protective plate under the housing and the engine
block. Tool width: 19 mm (3/4") and 13 mm.

230. Remove the cross piece carrier from the inter-

mediate wheel. Make sure that the cross piece carri-
er is not damaged.

227. Remove the flywheel damper nuts, 6 pcs. Tool

width: 13 mm. Carefully remove the damper from the
3 guide pins. Make sure that the splines are not
worn, that the springs are not damaged. Check also
that the spring package, including rivets etc., and
the damper as a whole are free from cracks.

231. Remove the bolt holding the carrier. Use coun-

terhold part no 9995034-7. Tool width: 17 mm. Pull
228. Remove the center bolt of the pulley and re- off the carrier from the belt wheel.
move the pulley. Tool width: 24 mm.

80
 235. Remove the pilot bearing locking ring for the in-
put shaft.
232. Remove the screws in the seal holder. Tool
width: 10 mm. The plate is also fixed by two of the
bolts holding the oil pan, spanner width: 12 mm. Re-
move the seal holder and then remove the seal (1).
Use special tool part no 9995025-5 for the small seal
and tool part no 9995283-0 for the large seal.

236. Use special tool part no 9994090-0 to remove

the input shaft bearing. Then remove the flywheel.
Tool width: 17 mm.

233. Lift up the oil pump gear wheel.

234. Pull out the intermediate shaft. 237. Turn the engine upside down. Remove the seal
NOTE! Make sure that the teeth of the intermediate holder. Tool width: 10 mm.
shaft gear do not damage the bearings in the engine NOTE! Also the 2 bolts holding the oil pan must be
block. removed.

81
 241. Remove the rod bearing caps. Tool width: 10
mm.
NOTE! The connecting rods and the connecting rod
caps are numbered and must not be mixed!

238. Remove the oil pan together with the gasket

from the engine. Tool width: 12 mm.

239. Remove the lubricating oil pump. 242. Push out the pistons from the cylinders, using a
Tool width: 1/2". wooden or plastic handle. Let the pistons drop on
NOTE! Take care of the bracket (1). some sort of soft material to prevent the pistons
from being damaged.

243. The main bearing caps are marked 1 to 5

counted from the timing gear end of the engine. Re-
240. Remove the seal ring (1). Do not leave it in the move the bearing caps. Tool width: 19 mm.
engine block.

82
 Classification

246. At each cylinder there is a letter punched into

the block, giving the class of the bore and that of the
piston. Oversizes are categorized as ’ÖD 1’ and ‘ÖD
2’. When reboring a cylinder, the new class must be
punched in.

Pistons

244. Lift out the crankshaft and remove the bearing

shells from the block and the caps.

The cylinder bores

247. Measure the pistons with a micrometer 90° to

the gudgeon pin hole and 7 mm (0.2756") from the
lower edge.
Piston diameter, standard:
(C-marked) = 95.940–95.950 mm (3.77717–3.77756")
(D-marked) = 95.950–95.960 mm (3.77756–3.77795")
(E-marked) = 95.960–95.970 mm (3.77795–3.77835")
(G-marked) = 95.980–95.990 mm (3.77874–3.77913")
(‘ÖD-1’) = 96.237–96.252 mm (3.78886–3.78945")
(‘ÖD 2’) = 96.537–96.552 mm (3.80067–3.80126")

245. Measure the cylinders with a ‘dial bore gauge’.

Measure for greatest wear transversally, just below
the T.D.C. Measure for smallest wear longitudinally
at the B.D.C.
Cylinder diameter standard:
C-marked: 96.00–96.01 mm (3.77953–3.77992") 248. Calculate the piston clearance:
D-marked: 96.01–96.02 mm (3.77992–3.78031")
Example:
E-marked: 96.02–96.03 mm (3.78031–3.78071") Measured cylinder bore ....... min. 96.025 max 96.030 mm
G-marked: 96.04–96.05 mm (3.78110–3.78150") (3.78051–3.7807")
Oversize: Measured piston diam. ........ max. 96.015 min. 96.010 mm
(3.78012–2.77992") 0.010 0.020
No 1: 96.3 mm (3.79134")
No 2: 96.6 mm (3.80315") The piston clearance should be max 0.080 mm
(.0031") before overhaul is required, overhauled en-
gines should have a clearance between 0.010 and
0.030 mm (.0004–.0012")

83
Piston rings

249. Remove the piston rings with piston ring pliers.

Remove all carbon deposits. Use a groove cleaning
tool to clean the piston ring grooves. A broken off
piston ring, ground to shape, can also be used. 251. When measuring the piston ring gap, the piston
Check carefully for damage, wear and cracks. ring should be inserted into the cylinder. Use a pis-
ton, upside down to correctly position the piston
ring. Measure the gap with the ring 15 mm (0.591")
above the lower edge of the cylinder. Use a feeler
gauge.
Upper compression ring ...................... 0.30–0.55 mm
(0.0118–0.0217")
Lower compression ring ...................... 0.30–0.55 mm
(0.0118–0.0217")
Oil scraper ring ................................... 0.30–0.60 mm
(0.0118–0.0236")

The piston pin

250. Check the axial wear of the piston rings. Use

new piston rings.
Upper compression ring .................. 0.060–0.092 mm
(0.00236–0.00362")
Lower compression ring .................. 0.040–0.072 mm
(0.00157–0.00283")
Oil scraper ring ............................... 0.030–0.065 mm
(0.00118–0.00256")

252. Check the clearance for the piston pin in the

piston. The fit is correct when the piston pin can be
pushed by the thumb though the piston pin hole with-
out any noticeable play.

84
 256. Check the crank bearings and the main bearing
journals. Measure with a micrometer at several loca-
tions around the diameter and length. The ‘out-of-
round’ on main and crank bearing journals must not
exceed 0.004 mm (0.000157"). The taper must not
exceed 0.004 mm (0.000157") on any of the jour-
nals. Should the measured values exceed the above
given tolerances, the crankshaft should be ground to
253. It should be possible, by light thumb pressure, the closest undersize. See ‘Technical Data’.
to push the gudgeon pin through the connecting rod
bushing (close running fit).

Assembly

254. Use special tool part no 9995309-3 to press out

the connecting rod bushing, if necessary.

257. Place the main bearing shells in their positions

in the block and in the caps. Then place the thrust
bearings on each side of number 3 main bearing.
The oil grooves should face outwards.

255. Press in the new bushing, using special tool

part no 9995309-3.
NOTE! Make sure that the lubricating holes in the
connecting rod and in the bushing line up with each
other. Check the connecting rod for straightness and 258. Oil the bearing shells and insert the crankshaft.
twist. If not straight, replace the connecting rod.

85
 262. Use piston ring pliers to install the piston rings.
Install the piston rings in accordance with the pic-
ture. The upper ring is chromium plated. The lower
259. Install the main bearing caps.
compression ring is marked ‘Top’. Turn the piston
NOTE! The main bearing caps are numbered 1 to 5,
rings on the piston so that the gaps are 120° apart
counted from the timing gear end. Oil the threads of
from each other.
the screws. Tighten with a torque wrench. Tightening
torque: 110 Nm (11.0 kpm/79.5 ft.lbs).

263. Install the bearing shells in the connecting rod

and in the caps. Oil the cylinder bore, piston and the
rod bearing. Check to make sure that the marking on
260. Check the axial clearance, which should be the piston is facing the timing gear cover when the
0.080–0.270 mm (0.00315–0.01063"). piston is installed in the cylinder. Use a piston ring
compressor to facilitate the installation.
NOTE! Turn the crankshaft so that the crank journal
for number 1 cylinder points straight downwards.
Push down the piston using a hammer handle.

261. Assemble the pistons and connecting rods so 264. Install the crank bearing caps so that the mark-
that the marking on the piston points forwards when ing matches with the one on the connecting rod. Oil
the number marking on the connecting rod is turned the threads and use a torque wrench to tighten.
towards the starboard side of the engine (the oil filter Tighten in 2 steps. Step 1: 20 Nm (2.0 kpm/15
side). Install the locking rings in the piston pins. ft.lbs). Step 2: Angle tighten 90°.
NOTE! Use new bolts should the length of the bolts
exceed 55.5 mm (2.185").

86
The lubricating oil pump
Overhauling

268. Check the axial clearance. It should be 0.02–

265. Remove the pipe from the lubricating oil pump 0.12 mm (0.00079–0.0047").
and also the 4 screws. Allen key: 5 mm.

269. Insert the piston, spring, guide pin and as-

semble the lower part of the pump. Install new seal
rings and the pipe.

266. Remove the relief spring, guide pin, piston and

the gear wheels. Clean all the parts and replace
damaged or worn parts.

270. Install new seal rings on the oil pump pipe. In-
stall the pump and the attachment yoke (1) for the
drainage of the oil trap. Tool width: 13 mm.

267. Install the gear wheels and check the gear

backlash, which should be 0.15–0.35 mm (0.0059–
0.0138").

87
 273. 230, 250, AQ131, AQ151: Coat the inside of
the flywheel with an anti-rust agent, ‘Tectyl’ or its
equivalent and install the flywheel. Tightening torque
271. Install the seal holder along with a new gasket
70 Nm (7.0 kpm/51 ft.lbs).
on the engine. Tool width: 10 mm.
NOTE! Always use new bolts.
NOTE! Cut off any protruding parts of the gasket.
251DOHC, AQ171: Turn the crankshaft to the
T.D.C. position for number 1 cylinder. Coat the in-
side of the flywheel with an anti-rust agent, ‘Tectyl’
or its equivalent. Then install the flywheel so that the
hole ‘A’ on the inside of the flywheel will end up 15°
below the horizontal line. Tightening torque: 70 Nm
(7.0 kpm/51 ft.lbs).
NOTE! Always use new bolts.

272. Press in a new seal ring in the rear seal holder

as follows:
A. Oil the contact surface of the seal, against the
holder, and the seal ring lips.
B. Push the seal onto the drift, part no 9995276.
C. If the shaft shows sign of having a wear surface 274. Install the support bearing for the input shaft,
where the seal was previously installed, then press using special tool part no 9991426-9.
the seal a bit further into the holder.
D. Remove one spacer ring from the drift if the old
sealing was flush with the seal holder.
E. Remove two spacer rings from the drift if the old
seal was located 3 mm inside the seal holder.
F. Let the spacer rings remain on the drift if the
crankshaft is free from wear damage.
G. Knock in the seal ring till the drift bottoms against
the crankshaft. Use standard drift part no 9991801.

275. Secure the bearing with the locking ring.

88
 Overhauling the flywheel housing

279. Inspect the flywheel housing and replace all

faulty parts. Use the following special tools to remove
and install bearings: Part no’s 884359-4, 884596-7
and 884599-4. Make sure you know which way the
276. Check that the O-ring on the underside of the
different seal rings are facing prior to removing them.
oil trap is not damaged. Replace if necessary. Install
Remove the seal ring (1) from the flywheel housing.
the oil trap (1). Make sure that the hose (2) is held
Check the primary shaft (2) and the bearing (3).
by the bracket (3) and the shoulder (4) on the pump.
Should any of them show any signs of damage, then
NOTE! Do not cut the hose!
remove the lock rings (4) and press out the shaft to-
gether with the bearing. Remove the seal ring (5) and
the lock ring (6) from the primary shaft as well as the
seal ring (5).
NOTE! Turn the seal ring facing the right way and
press the bearing (3) onto the primary shaft (2).
Press the shaft and the bearing into the flywheel
housing. Install the lock rings (4) and the seal ring
(1).
NOTE! To be installed with the “opening” facing out-
wards.
NOTE! Grease the seal rings abundantly prior to as-
277. Install the oil pan with a new oil pan gasket. sembly. Press grease into the lubricating channel (7).
Tighten all bolts except the 4 closest to the front
sealing flange. Tightening torque: 11 Nm (1.1 kpm/8
ft.lbs). Tool width: 12 mm.

278. Install the flywheel damper. Do not forget the 280. Carefully treat the primary shaft with an anti-
washers under the bolt heads. Tool width: 1/2". rust agent prior to assembly. Install the flywheel
housing. Tool width: 3/4".

89
 284. Grease the crankshaft seal abundantly and use
281. Install the protective plate on the underside of special tool part no 9995283-0 to install it.
the flywheel housing. Tool width: 1/2". Turn the en-
NOTE!
gine the right side up.
A. If the old seal ring has not left a wear surface on
the crankshaft, the seal should be pressed in edge
to edge with the flange.
B. Should the old seal ring have left a wear mark on
the crankshaft, the new seal ring is pressed in until
the mark on the tool is edge to edge with the flange.
Be careful not to damage the seal during installation.

282. Oil the bearings of the intermediate shaft. Then

carefully insert the intermediate shaft in the engine
block avoiding any damage to the bearings.

285. Grease the intermediate seal carefully and in-

stall it using special tool part no 9995025-5. Change
the contact surface against the shaft to give the lip
of the seal a new wear surface on the shaft. Be
careful not to damage the sealing during installation.
283. Put a new gasket on the engine block. Cut off
any protruding parts of the gasket. Install the front
seal holder without seal rings. Install the timing mark
plate (1). Install the front screws in the oil pan. Then
tighten all the screws. Tightening torque 10 Nm (1.0
kpm/7.5 ft.lbs).

90
286. Coat the hub of the belt wheel with a mineral-
based grease and install the belt wheel on the inter- 289. Install the cylinder head, see page 58, para-
mediate shaft. Install the carrier and the carrier graphs 129–133 and pages 70–72, paragraphs 183–
screw. Tighten the screw with a torque of 50 Nm 190 for 230, 250, AQ131, AQ151 and pages 68–70,
(5.0 kpm/36 ft.lbs). Use counterhold part no paragraphs 167–182 as well as page 73, paragraphs
9995034-7. Then install the cross piece carrier. 191–195 for 251DOHC, AQ171. Then remove the nut
and the washer on the belt tensioner (alternatively
the screw on 251DOHC, AQ171) and install counter-
hold part no 9995284-8. Install the thick washer on
the pulley and tighten the screw as follows:
Step 1: 60 Nm (6.0 kpm/43 ft.lbs)
Step 2: Angle tightening 60°.

287. Install the inner guide plate on the crankshaft

(turn the bevel towards the block). Coat the hub of 290. Carefully lift up the oil trap so that it can be
the crankshaft belt wheel with mineral-based grease. turned. Then install the oil pump gear and carefully
Install the belt wheel on the crankshaft. Then install turn back the oil trap. Be careful so that the hose
the outer guide plate (with the bevel facing out- down to the oil pan does not come loose.
wards).
NOTE! Make sure that the oil pump gear reaches its
bottom position in order to allow the oil trap to seal
against the engine block.

288. Then install the pulley.

NOTE! Make sure that the recess of the pulley coin- 291. Tighten the oil trap and at the same time the
cides with the guide pin (1) of the belt wheel. clamp of the cooling water pipe.

91
292. Check to make sure that the contact surfaces 293. Install the pulley on the circulation pump. Then
of the coolant circulation pump and the engine block install the toothed belt, sea water pump, alternator
are clean. Put a new seal ring on the pump and a and the V-belt.
new gasket on the engine block. Push the pump up- 294. Install the cylinder head. See under chapter 4.
wards against the cylinder head and tighten the
screws and the nuts.

92
5C Installing the external
components

The distributor 230, 250, AQ131–151

298. Turn the rotor so that the marking on the rotor

295. Turn the crankshaft to the firing position for is pointing approx. 60° away from the marking in the
number 1 cylinder. Check to make sure that the distributor.
camshaft cams for number 1 cylinder are pointing
away from each other and that the pulley marking is
indicating ‘0’.

299. Push the distributor down into its location in the

296. Put on a new gasket and install the valve cover engine block and make sure that the rotor lines up
and the plate for the belt marking. Make sure that with the marking in the distributor housing. Tighten
the belt marking coincides with the recess of the the distributor in this position.
plate. Adjust if necessary.

297. Remove the distributor cap. 300. Install the distributor cap.

93
 303. Install the fuse bracket and the wiring harness.
Clamp the wiring harness to the flywheel housing
Changing the breaker points 230, 251, AQ131, and tighten the ignition coil to its bracket.
AQ151
301. Remove the distributor cap (1) and the rotor
(2). Then loosen the screw (3) and the flat terminal
(4) and remove the breaker point set. Install a new
breaker point set. The contact gap should be 0.40
mm (0.01575"). At the same time replace the con-
denser (5) by loosening the screw (6). Tighten the
new condenser and connect the flat terminal. Push
on the rotor and install the distributor cap.
NOTE! During the test run, check the dwell angle
and adjust if necessary. See under “Technical Data”.

304. Install the cooling water pipe

302. Install the bracket for the ignition coil on the en-
gine.

305. Install the starter motor.

94
 308. Install a new O-ring and install the oil cooler on
the engine but do not tighten it.

306. Connect all wires to the alternator, the starter

motor and the temp sender. The wire to the oil pres-
sure sender is connected later. Connect the ignition
wires to the spark plugs and the ignition coil.

Overhauling the oil cooler 250,

251DOHC, AQ151, AQ171

309. Connect the cooling water pipes along with new

rubber sealings to the oil cooler. On model 230,
AQ131 the cooling water pipe goes straight from the
exhaust manifold to the heat exchanger. The picture
shows model 250, AQ151.

307. Remove the center screw (1) and remove both

end covers (2) and (3). Remove the O-rings (4) in-
stalled on the cooler insert. Push out the insert (5).
Watch out for oil spillage! Clean and use com-
pressed air to blow out the insert internally. Check
that the passage in the drain cock (6) is not clogged.
Install the insert in the housing and install the O-
rings on the insert. (Replace the O-rings if neces-
sary!). Install the end covers and tighten them by
the center screw. Replace the O-ring (7) should it be
damaged. Check and replace the O-ring (8) if neces-
sary.

310. Tighten the cooling water pipe to the exhaust

manifold. Tool width: 10 mm.

95
311. Tighten the oil cooler to the engine. Tool width:
29 mm.
313. Oil the gasket of the oil filter and install the fil-
ter by hand until the rubber gasket touches the en-
gine block. Then turn the filter by hand a further 1/2
turn. Check the oil pressure and also for leakages
around the oil filter during the first test run.

312. Connect the wire to the oil pressure sender.

Tool width: 3/8". Then pull over the protective rubber
cap (1). Also clamp the wire to the cooling water
pipe (2).

96
 References to Service Bulletins

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 Notes

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AB Volvo Penta
Customer Support
Dept. 42200
SE-405 08 Gothenburg
Sweden
7732007-5 English 05-1999