Fuel system 8

Injector, setting (old type)

Connect the injector to a hand pump after removing cap screw 20

fig. 169.
By means of the tool - se.no. 7107-1460-028 - check that the
setting pressure is 130÷145 bar.
Adjust, if necessary, by changing the spacer located under the
spring.
There are eleven different spare part spacers from 1 to 2 mm.
When you replace the spring, the setting should be made at a
pressure higher than 10 bar to compensate for adjustments in
operation.
Check the needle seal by slowly actuating the hand pump for 10
seconds, until you reach abt. 130 bar.
If the nozzle drips, replace it.
177

Setting of injector according to current pump/injector unit

Remove the non-return valve leaving its metal gasket and fit a cap
screw in its place, that is part of tooling 7107-1460-074.
Mount then head 1 and coupling 2.
Then connect a hand pump as shown in the picture.
The pressure setting must be 140÷155 mm bar.

178

Injector, nozzle projection

To avoid excessive compression of the spark arrester A, fig. 181,

check projection B of the nozzle fig. 179.
B = 6.80÷7.05 mm.
If this measure is larger put spacer 2 between ring nut 1 and copper
gasket 3.
0.25 mm thick spacers are available.

179 180

Injector, spark arrester

Every time you remove the pump/injector you must replace the
spark arrester, the copper gasket, the oil O-ring, as well as the 2 fuel
O-rings.
Insert the spark arrester in the injector housing with surface A
pointing upwards.

€ Tighten simultaneously both nuts that fasten it to the head at 20

Nm.
For engines with the injectors fixed with self-locking nuts, tighten
the nuts at 23 Nm.

 See page 24 for periodic maintenance details.

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 8 Fuel system

Injection advance control and regulation

- Dismount the rocker arm cover, see page 40.

- Position the device on the head, in contact with cylinder no. 1.
- Mount the dial gauge on the valve controlled by tool ref. 1460.048.
- Via lever 1 of the tool, open the valve until it comes into contact
with the piston.
- Then rotate the crankshaft until the TDC is read in the dial gauge.
Then reset the hundredths.
- Remove the fuel pipes.
- Remove the O-ring in contact with the non-return valve and
replace it with the appropriate gasket - equipment component part
ref. 1460.074. Once the check has been completed, remove the
gasket and refit the O-ring.
Connect tool 1460.074 on pump n° 1. This will automatically
182
position the control lever to the maximum delivery. The tool is
provided with 3÷4 couplings for connection to a tank that must be
not lower than 30 cm from the pumps level. Coupling 2 is
equipped with a plastic pipe with internal drip collecting wire.
- Put cylinder 1 under compression and open the tank tap. Fuel
diesel will start to flow out from coupling 2.
- Slowly rotate the engine towards TDC 1 until the diesel fuel stops
leaking out.
- At this point with lever 1 (of fig. 182) move again the valve until it
touches the piston and read on the dial gauge how many
hundredths are missing from the previously reset value (TDC).
- To convert hundredths into degrees, consult the table below.
- Repeat the operation on the other cylinders.

183

Injection advance for currently used pump/injector unit

LDW 502 LDW 602-903-1204-1204/T LDW 702-1003-1404
α
(mm) (mm) (mm)
18° 1.947 2.367 2.468
17° 1.739 2.115 2.205 Engine Code Reference n° Rpm α
16° 1.543 1.876 1.956
502-602
15° 1.358 1.651 1.721 6590-285 272-1 1500÷2999 8°÷10°
903-1204
14° 1.184 1.440 1.501
502-602
13° 1.022 1.242 1.296 6590-285 272-1 > 3000 12°÷14°
903-1204
12° 0.871 1.059 1.105
502* 6590-307 272+ 3000÷3600 10°÷12°
11° 0.733 0.891 0.930
10° 0.606 0.737 0.769 702-1003
6590-290 235-4 1500÷2999 8°÷10°
9° 0.491 0.597 0.623
1404

8° 0.388 0.472 0.493 702-1003

6590-290 235-4 3000÷3600 12°÷14°
7° 0.297 0.362 0.378
1404

6° 0.218 0.266 0.277 702-1003

6590-290 235-4 > ÷3600 13°÷15°
1404

1204/T 6590-290 235-4 1500÷3600 6°÷8°

* With aluminuim crankcase

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 Fuel system 8
Static injection advance tuning

If the injection advance value found does not correspond to the

previously described value, adjust the screw E and repeat the test.
Rotating screw E by ½ turn will change the injection advance by 5°.
If turned clockwise, injection is advanced.
In the opposite direction, injection is delayed.

184

Injection advance references on timing belt protector

The method of checking injection advance is essentially the same as

that described in fig. 182 with one difference: instead of using the
device se.no. 7107-1460-048 with which you measure piston
lowering with respect to the Top Dead Centre, you use references A
and C on the timing belt protector and reference D located on engine
pulley.
When D coincides with A the piston has reached its TDC.
When D coincides with C the piston is in injection advance position.

185

TDC (Top Dead Center) references

D coincides with A = TDC of 1st cylinder of all series engines, of 4th

cylinder LDW 1204-1204/T-1404, and of 2nd
cylinder LDW 502.
E coincides with A = TDC of the 2nd cylinder LDW 903-1003.
F coincides with A = TDC of 2nd cylinder LDW 602-702., of 3rd
and 2nd cylinder LDW 1204-1204/T-1404.
G coincides with A = TDC of 3rd cylinder LDW 903-1003.

Note: Following the arrow’s rotation direction, the combustion

order for LDW 903-1003 is D, G, E (1st - 3rd - 2nd cylinder
respectively. As to LDW 1204-1204/T-1404 the sequence is
D, F, D, F (1st– 3rd– 4th and 2nd cylinder).
186

Tester and special coupling for injection advance control (Old-

type injection pump)

1 Special coupling. Serial number: 7107-1460-028

2 Injection advance tester. Serial number: 7271-1460-024.

Remove the cap on the pump/injector casing and in its place screw
on coupling 1.
On this coupling tighten the tester 2.

Note: When reassembling the cap on the pump/injector unit, check

its seal.

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 8 Fuel system

Static injection advance regulation

Fill the tank and operate the fuel pump.

Set the pump/injector delivery control rod (ref. A fig. 187) at half-
stroke.
Bring the piston to the top dead centre of compression. Fit a 13
mm hexagon wrench on the injection advance adjusting screw lock
nut. By turning the wrench forth and back you prime the injection
pump, thus enabling the tester to be drained.
With the piston at its TDC, operate lever 2 fig. 188 and bring the
drain valve into contact with the piston. Then reset dial gauge.
Go back ¼ of a turn moving the crankshaft anticlockwise. Then
turn forward again very slowly
observing the fuel level inside the tester. As soon as the level
changes, then stop. You reached the static injection advance.
188
By actuating lever 2 check piston lowering with respect to the TDC
that shall be between 0.89 and 1.24 mm for LDW 602-903-1204,
and between 0.73 and 1.02 for LDW 502 engine model.
The table on page 80 shows both piston lowering expressed in mm,
with respect to the TDC, and the corresponding rotation of the
crankshaft, expressed in degrees.
The static injection advance in degrees α = 11° to 13° refers to all
engines for adjustments from 1500 / 3600 rpm.

Preliminary steps to pump/injector unit delivery balancing test

Closing the oilhole

To perform this test you must remove the rocker arms cover and
close hole 1 with an M 8x1.25 or M 10x1.5 screw (on latest model
engines) not longer than 8 mm. Also remove the copper gasket.
If the camshaft and rocker arms are dry, lubricate them with engine
oil.

Note: If you only want to check the nozzle it is not necessary to

balance the deliveries; provided that when you dismount the
rod you do not loosen adjusting screws 1 and 2 (fig. 193).

189

Test head B assembly

Remove fuel pipe A and mount one test head B in its place per
pump/injector.
The test heads complete with pipes are supplied together with
instrument ref. 7104-1460-069.

190 191

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 Fuel system 8
Instrument connection

Place the instrument 1, se.no. 7104-1460-127 at least 20 cm above

the pump/injector level.
Connect pipe A (outlet from every instrument test piece) with pipe A
(inlet of every pump/injector) and pipe B (return to the instrument)
with pipe B (outlet from the pump/injector).
Open tap 2 and 3 of each pipe and fill the instrument with diesel.
Start the engine and bring it to 1500 rpm idle running.
Close the fuel supply to the engine from the instrument’s tank using
lever 4 and after 1 minute observe the levels in the test piece.
If a level goes down more than the others it is necessary to decrease
the delivery of the corresponding pump (see below) and vice versa
to increase the delivery if the level increases.
192

Injection pumps delivery balancing

In case the balancing error read on the test pieces is greater than 2
cm³/min, then injection pumps deliveries should be adjusted.
Plate 4 and rod 3 are blocked by screws 1 and 2. Loosen them.
Move plate 4 rightwards with respect to rod 3 if you want to
increase delivery.
If moved leftwards delivery decreases. Make very small movements
with the plate.

€ Tighten screws 1 and 2 at a torque of 1,1 Nm.

Note: Each time a pump/injector is replaced it is necessary to

balance the deliveries.
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