TM 5-3895-379-23
THEORY OF OPERATION - CONTINUED
0003 00
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 cylin-
der 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 cylin-
der 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 pro-
vide 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 tem-
perature 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 an 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 00-6
