TM 9-2320-387-24-l
1 l-20. COOLING SYSTEM OPERATION
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The cooling system removes excess heat from the engine, engine oil, transfer oil, and transmission oil. Major
components of the cooling system are:
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ENGINE TEMPERATURE
SENDING UNIT - Sends signal indicating coolant temperature to
gauge on instrument cluster.
ENGINE TEMPERATURE
SWITCH - Sends signal to activate control valve system to operate fan
when engine temperature exceeds 220°F (104°C) and deactivates when engine temperature drops
below 190°F (88°C).
WATERCROSSOVER
- Collects coolant from cylinder heads and channels it to the thermostat
housing where it is redirected through the cooling system.
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.
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.
OIL COOLER - Directs engine oil (lower half of cooler), power steering oil (lower half of cooler), and
transmission oil (upper half of cooler) through a series of fins or battles so outside air can remove
heat from oil.
SURGE TANR - Filling and expansion point for cooling system.
PERSONNEL HEATER - Provides heat for personnel and interior of vehicle.
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