COOLING SYSTEM

INTERNAL COMBUSTION ENGINE

POWERED UNITS

HYSTER
PART NO. 897934 700 SRM 626
700 SRM 626 General

General
This section has the description and the checks for The cooling system has the following parts: radiator,
some parts of the cooling system. Prodecures for auxiliary coolant reservoir, water pump, thermostat,
cleaning the radiator and troubleshooting are also fan, and fan shroud. See Figure 1.
included in this section.

AUXILIARY COOLANT RESERVOIR 5. TOP RADIATOR HOSE

RADIATOR CAP 6. FAN SHROUD
ON

RADIATOR 7. BOTTOM RADIATOR HOSE

RADIATOR DRAIN VALVE 8. PORTS FOR TRANSMISSION OIL COOLER

Figure 1. Typical Radiator Arrangement

Description 700 SRM 626

Description
The purpose of the cooling system is to control the by another spring. The vacuum valve opens to re-
operating temperature of the engine (and in some lieve the vacuum created when the coolant temper-
units, the transmission, brakes, and hydraulic sys- ature decreases. In certain conditions this vacuum
tem). A centrifugal water pump circulates coolant can cause the radiator or top hose to collapse.
through passages in the engine block and the radi-
ator. A thermostat is installed in the water outlet THERMOSTAT
fitting on the engine. As the coolant flows through
the radiator, the fan moves air through the radiator The thermostat is a device that controls coolant flow
to help cool the system. by opening and closing to regulate coolant temper-
ature. The thermostat uses a wax pellet to control
The coolantis a mixture of water and antifreeze. The its operation. The wax pellet expands when it is
antifreeze prevents the coolant from freezing in cold heated and contracts when it is cold. When heated,
weather, and thereby preventing damage to the en- the wax pellet pushes on the piston, causing the valve
gine and radiator. The antifreeze also prevents rust in the thermostat to open. As the wax pellet cools,
and lubricates the water pump. it contracts and lets a spring close the valve. When
the engine is first started and the coolant is cold,
RADIATOR the thermostat remains closed. During this time the
coolant circulates through the engine, letting it warm
The radiator is the heat exchanger for the cooling sys- quickly. As the engine becomes warm the thermostat
tem. The fan causes air to flow through the radiator opens, letting coolant circulate through the radiator.
and reduces the temperature of the coolant. The aux-
iliary coolant reservoir is connected to the radiator by The opening and closing of the thermostat helps keep
a hose. As the engine gets hot, the coolant expands. the coolant within the operating limits of the system.
During expansion, coolant moves from the radiator The same thermostat is used for summer and winter
to the reservoir. When the engine stops, the coolant seasons. Do not operate the engine without a ther-
becomes cool and contracts. The coolant in the reser- mostat. The engine will take longer to get warm and
voir flows back into the radiator. In this way, the may run improperly. See Figure 2.
radiator is kept filled with coolant during normal op-
eration.

On units with a powershift transmission, an oil

cooler is built into the radiator. Oil from the trans-
mission flows through coils in the radiator tank to
help control the oil temperature.

RADIATOR CAP
The radiator cap is a pressure-vent type that lets the
pressure in the cooling system increase to 103 kPa
(15 psi). The pressure in the system prevents va-
por from forming in the coolant flowing to the wa-
ter pump. This action maintains the efficiency of the
water pump and the performance of the cooling sys-
tem. The increase in pressure also raises the boiling
point of the coolant mixture to approximately 125°C 4 HMO60001
(257°F) at sea level.
1. PISTON 5. WAX PELLET
The radiator cap has a pressure valve and a vac- 2. VALVE SEAT 6. FRAME
3. SPRING 7. FLANGE
uum valve. The pressure valve is held against its 4. DIAPHRAGM 8. VENT HOLE
seat by a spring. The pressure valve opens when
the pressure in the cooling system exceeds 103 kPa Figure 2. Typical Thermostat
(15 psi). The vacuum valve is held against its seat
700 SRM 626 Cooling System Checks

WATER PUMP FAN AND FAN SHROUD

The centrifugal-type water pump is installed at the The fan is used to provide airflow through the radia-
front of the engine block. The inlet for the pump is tor at all engine speeds. The fan is a pusher-type or
connected to the bottom of the radiator by a hose. puller-type and can be installed on the water pump
From the pump, coolant passes through the passages or on a separate hub. The fan is driven by a drive
in the engine block to the top of the radiator. The belt from the engine crankshaft.
thermostat controls the flow of coolant through the
engine and radiator. The fan shroud ensures the air flow from the fan goes
through the core of the radiator.

Cooling System Checks

RADIATOR 2. Mix solution of water with 33% antifreeze. Heat
solution to 14°C (57°F) above temperature on
& WARNING thermostat.
During engine operation, be careful not to 3. Hold thermostat with wire and put it in solution.
touch the fan, pulleys, or drive belts. Contact Stir solution. If operating correctly, thermostat
with these parts can cause serious injury. will open.
NOTE: The Repair procedures for the radiator are in 4. Remove thermostat and put in same solution at
the Frame section of the Service Manual. =12°C (10°F) below temperature on thermostat.
Valve must close completely.
To check for water flow restrictions in the radiator,
run the engine until it is warm. Shut the engine OFF
and feel the radiator. The temperature must be even
across the radiator. (The radiator will be hotter near
the top radiator hose.) Cold spots on the radiator
indicate restrictions.

Tf the radiator has leaks, have it repaired by trained

personnel.

THERMOSTAT

& WARNING
During engine operation, be careful not to
touch the fan, pulleys, or drive belts. Contact
with these parts can cause serious injury.

& CAUTION
DO NOT operate the engine without a ther-
HMO060004
mostat. The engine and cooling system can be
damaged. 1. FAN 5. THERMOSTAT
2. SPACER 6. THERMOSTAT
NOTE: Repair procedures for the thermostat are in 3. HUB/PULLEY HOUSING
the Engine section of the Service Manual. 4. WATER PUMP
1. Remove thermostat from cooling system. See Figure 3. Cooling System Components Typical
Figure 3. Arrangement
Radiator Cleaning 700 SRM 626

WATER PUMP FAN AND FAN SHROUD

A WARNING A WARNING
During engine operation, be careful not to During engine operation, be careful not to
touch the fan, pulleys, or drive belts. Contact touch the fan, pulleys, or drive belts. Contact
with these parts can cause serious injury. with these parts can cause serious injury.

NOTE: Repair procedures for the water pump are in

the Engine section of the Service Manual. @ WARNING
DO NOT try to repair a damaged fan. If a fan
Run the engine until it is warm. Check the operation has a bent blade or is cracked, install a new fan.
ofthewater pump by holding the top radiator hose. If A damaged fan can break during use and cause
the pump is operating, there will be pressure surges damage or serious injury.
in the hose. See Figure 3.
NOTE: Repair procedures for the fan and shroud are
EXHAUST LEAKS in the Frame section of the Service Manual.

1. When installing fan, make sure correct spacers

& WARNING are installed and mounting capscrews are tight.
During engine operation, be careful not to See Figure 1 and Figure 3.
touch the fan, pulleys, or drive belts. Contact
with these parts can cause serious injury. 2. When installing fan shroud, make sure cor-
rect seals are on shroud. Before tightening
To check for exhaust leaks into the cooling system, capscrews, make sure clearance around cir-
use a kit for this purpose. Follow the manufacturer's cumference of fan is even with shroud. Also
instructions when doing the test. make sure 1/3 to 1/2 of cross-section of fan blade
extends into fan shroud.

3. Make sure WARNING labels are installed on

shroud.

Radiator Cleaning
DRAIN 2. Open drain valve or remove bottom radiator
hose. Remove drain plug from engine block to
& WARNING drain engine.
DO NOT remove the radiator cap from the radi-
ator when the engine is hot. When the radiator
CLEAN
cap is removed, the pressure is released from
the system. If the system is hot, the steam and & CAUTION
boiling coolant can cause burns. Disposal of lubricants and fluids must meet lo-
cal environmental regulations.
& CAUTION 1. Drain cooling system. Fill cooling system with
Disposal of lubricants and fluids must meet lo- clean water.
cal environmental regulations.
2. Install radiator cap. Run engine until top radia-
1. Let coolant cool to room temperature. Put drain tor hose is hot. Stop engine and let engine cool.
pan under radiator. Remove radiator cap. See
Figure 1.
700 SRM 626 Radiator Cleaning

3. Drain water from radiator. If water is dirty, fill NOTE: Units with a Mazda engine must use a boron-
system with water and repeat procedure until free type of antifreeze.
water is clean.
2. Fill cooling system with mixture of 50% water
and 50% ethylene glycol antifreeze. Install ra-
@ CAUTION diator cap.
Follow the manufacturer’s instructions when
using a chemical radiator cleaner. The 50/50 mixture will protect the cooling system
to =37°C (-35%).
4. If water does not clean system, use chemical ra-
diator cleaner. 3. Usesame coolant mixture to fill auxiliary coolant
reservoir to FULL mark. See Figure 4.
& CAUTION 4. Start and run engine until thermostat opens.
Follow the manufacturer's instructions when (Top radiator hose will be warm.)
using special equipment to reverse clean the
radiator. 5. Check coolant level at auxiliary coolant reservoir.
Add coolant as necessary to keep level between
NOTE: On lift truck models S3.50-5.50XM FULL and ADD marks.
(S70-120XM) (E004), the cooling system may be
equipped with an optional radiator screen. 4 5
5. Ifradiator or cooling system is very dirty or has
restriction, use reverse cleaning method. This
3
method uses air pressure to force water through
radiator in opposite direction of normal flow.

& WARNING
Compressed air can move particles so they
cause injury to the user or to other personnel.
Make sure the path of the compressed air
is away from all personnel. Wear protective
goggles or a face shield to prevent injury to
the eyes.

6. Check radiator fins. Clean exterior of radiator

with compressed air or water as needed.
HMO060003
FILL
ADD MARK
FULL MARK
orhwN=

1. Install drain plug in engine block. Close drain

valve or install bottom radiator hose as needed. AUXILIARY COOLANT RESERVOIR
FILL CAP
RADIATOR CAP
A WARNING
Do not use an alcohol or methanol-base an- Figure 4. Auxiliary Coolant Reservoir
tifreeze. They are flammable and can cause
personal injury or damage to the lift truck.
Troubleshooting 700 SRM 626

Troubleshooting

PROBLEM POSSIBLE CAUSE PROCEDURE OR ACTION

Coolant leaks. There is a leak in the radiator. Repair radiator.

There is a leak in a radiator hose or Install new hoses.

coolant hose.

There is a leak from a plug or sensor Check sensors and plugs, and repair
in the engine block. leaks.

Water pump leaks. Install new water pump.

Thermostat housing leaks. Install new thermostat housing.

Check for correct installation of ther-
mostat.

Cylinder head gasket is damaged. Install new head gasket.

Cylinder head is cracked. Install new cylinder head.

Engine block is cracked. Install new cylinder block.

The engine is too hot during There is not enough coolant in the Check coolant level in radiator and
operation. cooling system. coolant recovery bottle. Add coolant
to correct level.

The radiator is dirty. Drain and clean radiator. Clean radi-

ator fins with low pressure air or wa-
ter in reverse direction of normal air
flow. Be careful not to bend fins. Re-
fill with clean coolant.

The drive belt for water pump is not Check water pump drive belt. Adjust
adjusted correctly, worn, or broken. or install new belt as required.

The thermostat is wrong heat range Check heat range. Install new ther-
or does not operate correctly. mostat.

The cooling system has restrictions. Drain and back-flush engine and ra-
diator. Refill with clean coolant.

The water pump is worn or damaged. Install new water pump.

The exhaust system has restrictions. Check exhaust system. Remove re-
strictions.

Ignition timing is not correct. Check and adjust timing.

Exhaust leaks into coolant. Head gasket(s) leaks. Install new gasket(s).

Cylinder head is damaged. Install new cylinder head.