TM10-3950-672-24-2
Coolant System
Coolant System Components and Flow
The following illustration identifies the significant features of the coolant system.
A. Coolant is drawn from the radiator by the integrally mounted water pump. The output from the water pump empties
into the oil cooler cavity of the cylinder block.
B. The coolant then circulates around each cylinder and crosses the block to the fuel pump side of the engine.
C. Coolant then flows up into the cylinder head, crosses over the valve bridges and down the exhaust manifold side of
the engine to the integral thermostat housing.
D. As the coolant flows across the head toward the thermostat housing, it provides cooling for the injector nozzle. When
the engine is below operating temperature, the thermostat is closed, and the coolant flow bypasses the radiator and
goes to the water pump inlet via internal drillings in the block and cylinder head.
When operating temperature is reached, the thermostat open, blocking the bypass passage to the water pump and
opening the outlet to the radiator.
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Caution: Never operate the engine without a thermostat. Without a thermostat, the coolant will not flow to the
radiator and the engine will overheat.
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