TM 5-3895-379-23-1
0003
COOLING SYSTEM
1. General. Coolant from the bottom of the radiator passes through the centrifugal water pump which is
installed on the front of the engine timing case. The pump is gear-driven from the gear of the fuel injection
pump and assists the flow of coolant through the system. From the pump, coolant goes through a passage
in the timing case to the front of the cylinder block. The coolant passes through a passage in the left-side
of the cylinder block. Some of the coolant passes through a lubricating oil cooler before going to the rear of
the cylinder block. The coolant then passes around the cylinder and up to the cylinder head. Coolant leaves
the front of the cylinder head and passes to the thermostat housing. If the thermostat is closed, the coolant
goes directly through a by-pass to the inlet side of the water pump. If the thermostat is open, the coolant
passes to the top of the radiator. A push-type fan forces air through the radiator, relieving the coolant of
heat.
2. Radiator. The radiator acts as a coolant reservoir. The radiator cools the heater coolant from the engine
while it is being stored.
3. Water Pump. The centrifugal water pump draws coolant from the radiator and forces it into the coolant
passages in the engine. After the coolant has flowed through the entire engine, pressure from the water
pump pushes it back into the radiator. The water pump is gear driven from the engine.
4. Radiator Hose (Two Hoses). The radiator hoses connect the radiator to the water pump and engine. These
hoses provide a passage for coolant transfer between the radiator and the engine.
5. Fan. The cooling fan pushes air through the radiator to aid in helping lower the temperature of the coolant
by relieving heat from the coolant.
6. Temperature Sending Unit. The temperature sending unit sends a signal to the engine coolant temperature
warning light when the engine coolant temperature is too high for safe operation.
7. Engine Coolant Temperature Warning Light. The engine coolant temperature warning light is connected
to the temperature sending unit. When the sending unit signals high operating temperature, the warning
light will illuminate to alert the operator. A warning horn is connected to the light for both a visual and audible
warning.
8. Thermostat. The thermostat controls the temperature of the coolant and engine. The thermostat blocks the
path of the coolant traveling back to the radiator. Until the engine reaches proper operating temperature,
the thermostat will not allow the coolant to pass into the radiator.
0003-6
03/15/2011Rel(1.8)root(thrywp)wpno(G00006)
