TM 9-2320-280-20-1
1-38
Change 1
1-20. COOLING SYSTEM OPERATION
The cooling system removes excess heat from the engine, engine oil, transfer oil, and transmission oil. This
system is identical on all models covered in this manual. Major components of the cooling system are:
B
ENGINE TEMPERATURE SWITCH – Sends signal to activate control valve system to operate fan
when engine temperature exceeds 215°F (102°C) and deactivate when engine temperature drops
below 190°F (88°C).
A
ENGINE TEMPERATURE SENDING UNIT – Sends signal indicating coolant temperature to
gauge on instrument cluster.
D
THERMOSTAT – Shuts off coolant return flow to radiator until temperature reaches 190°F (88°C).
Coolant is then directed to the radiator through the radiator inlet hose.
C
WATER CROSSOVER – Collects coolant from cylinder heads and channels it to the thermostat
housing where it is redirected through the cooling system.
E
RADIATOR – Directs coolant through a series of fins and baffles so outside air can dissipate excess
engine heat before the coolant is recirculated through the engine.
F
G
H
OIL COOLER – Directs engine oil (lower half of cooler) and transmission oil (upper half of cooler)
through a series of fins or baffles so outside air can remove heat from oil.
SURGE TANK – Filling and expansion point for cooling system.
PERSONNEL HEATER – Provides heat for personnel and interior of vehicle.
