1-20.1. COOLING SYSTEM OPERATION (SERIAL NUMBERS 300000 AND ABOVE)
The cooling system removes excess heat from the engine, engine oil, transfer case oil, and transmission oil.
Major components of the cooling system are:
TRANSFER CASE Directs engine coolant through a series of fins or baffles so coolant can
remove heat from transfer case oil.
ENGINE TEMPERATURE SENDING UNIT Sends signal indicating coolant temperature to
gauge on instrument cluster.
WATER CROSSOVER 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) 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.
DIFFERENTIAL COOLER Directs engine coolant through a series of fins or baffles so coolant
can remove heat from differential oil.