TM 5-3810-306-20
COOLING SYSTEM
General
The cooling system consists of the radiator, engine cooling circuit, thermostats, water pump, turbocharger aftercooler filter,
and the connecting hoses. The temperature is controlled by two 180 degree F (82 degrees C) thermostats located
between the top of the engine and the top of the radiator.
The function of the cooling system is to maintain a specific operating temperature for the engine. Some of the heat
generated by the engine is absorbed by the coolant flowing through the passages in the cylinder block and head. Then,
heat is removed from the coolant as it flows through the radiator.
Radiator
The radiator has a capacity of 44 quarts and contains a mix of 50/50 antifreeze coolant and water. Coolant is stored in the
radiator and is drawn by an integrally mounted water pump. Air forced through the fins of the radiator by a fan cools the
coolant pumped through the radiator.
Water Pump
The water pump pulls coolant from the bottom of the radiator and pumps it through the engine back to the top of the
radiator for cooling. Reduced or interrupted flow will result in the engine running hot. The pump is belt driven from the
crankshaft pulley.
Coolant Overflow Tank
A coolant overflow tank is installed on the inside of the engine hood assembly. The tank collects excess coolant
overflowing from the radiator.
Fan Drive Belt
The fan drive belt is used to drive the fan, alternator, and water pump pullies. An automatic belt tensioner is used to
prevent belt slippage. A malfunction in the belt tensioner reduces pump impeller speed, coolant flow, and prevents the
battery from charging properly.
Thermostats
From the liner cavities, the coolant flows through cast openings into the lower manifold, and into the thermostat cavity.
Thermostats control coolant temperature. When the coolant temperature is below operating temperature, the thermostats
are closed, and coolant is bypassed to the water pump inlet. As coolant temperature increases to the intermediate range,
both thermostats open, and coolant flow to the bypass will be partially restricted. At engine operating temperature the
thermostats are open and the bypass is closed.
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