SkyTrak 8042 Service Manual - Manual (Page 376)

7B.9 Model 8042, 10042, 10054 Legacy Rev. 10/03
Engine: Cummins QSB4.5T
7B.6 ENGINE COOLING SYSTEM
The engine cooling system is a closed, pressurized
system that consists of coolant passages in the engine,
plus the oil cooler, thermostat, water pump, coolant
heater, hoses, radiator and radiator overflow bottle. The
engine is cooled by the circulation of coolant through
passages in the cylinder block, engine head and radiator.
Circulation is by thermo-siphon action, assisted by an
impeller-type water pump, driven by a fan belt from the
crankshaft pulley.
The water pump bearings are pre packed with a special
grease and DO NOT require service. Replace a faulty
water pump. General engine cooling specifications and
maintenance procedures are listed in Section 2, “General
Information and Specifications.”
7B.6.1 Radiator Pressure Cap
The cooling system is designed to use a radiator
pressure cap to help prevent the coolant from boiling. In
addition, the pressure helps to eliminate the formation of
steam pockets within the engine and ensures coolant
circulation throughout all coolant passageways of the
engine. For a 210° F (99° C) system, use a 13 psi
(90 kPa) radiator cap. An incorrect or malfunctioning cap
can result in the loss of coolant and a hot-running engine.
7B.6.2 Thermostat Replacement
Before considering thermostat replacement, check the
coolant level, fan belt tension and instrument cluster
temperature indicator.
• If the engine seems to take a long time to warm
up, the thermostat may be stuck in the open
position and requires replacement.
• If the engine runs hot, check the temperature of
the upper radiator hose.
• If the hose is not hot, the thermostat may be
stuck in the closed position.
• If the engine has overheated, performance may
suffer, indicating other damage including a
leaking cylinder head gasket, cracked cylinder
head or block, and/or other internal engine
damage.
a. Thermostat Removal
1. Park the vehicle on a firm, level surface. Level the
vehicle, ground the attachment, place the travel
select lever in the (N) NEUTRAL position, place the
neutral lock lever in the (N) NEUTRAL LOCK
position, engage the parking brake switch and shut
the engine OFF.
2. Place an Accident Prevention Tag on both the
ignition key switch and steering wheel, stating that
the vehicle should not be operated. Refer to Section
1.5, “Accident Prevention Tags.”
3. Disconnect the negative (-) battery cables (2) from
the batteries.
4. Unlock, unlatch and open the side and rear engine
doors. Allow the engine to cool before proceeding.
Draining the cooling system while the engine is hot
can cause cracks in the engine block.
WARNING:
DO NOT attempt this
procedure when the engine is hot. Wait for the
engine, muffler and tailpipes to cool down
before proceeding. Failure to do so could result
in severe burns.
MH4440
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