TM 5-3805-298-23-1
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COOLING SYSTEM
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Engine Cooling
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During engine operation the water pump circulates engine coolant from the radiator into the engine oil cooler and
the cylinder block. The engine oil cooler transfers heat from the engine oil to the engine coolant.
The engine coolant flows out of the cylinder block and through the water temperature regulator housing. When the
engine coolant is below normal operating temperature, the water temperature regulator remains closed and engine
coolant flows through the bypass tube back to the water pump bypassing the radiator. When the engine coolant is
at normal operating temperature, the water temperature regulator opens and engine coolant flows to the radiator
through the radiator inlet hose.
Figure 1. Engine Cooling.
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Hydraulic Demand Fan
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Air flow through the radiator and coolant pack is controlled by a hydraulically driven fan mounted on the rear of
machine. The fan is controlled by the transmission ECM and gets hydraulic pressure from the brake and fan drive
pump.
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Arctic Heater (Optional)
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This machine may be equipped with an optional arctic heater. The arctic heater burns fuel from the machine's fuel
tank to heat the engine coolant. A pump in the arctic heater circulates the heated engine coolant through the
engine block. The arctic heater has four additional batteries connected to the standard equipment batteries. These
additional batteries supply the power needed to run the arctic heater and provide additional power to start the
engine under cold start conditions.
