1-14. ENGINE COOLING SYSTEM. The flow through the engine cooling system is shown in figure 1-22.
a. Engine and Radiator. The system is a rapid warm-up system with two semi-blocking thermostats. At coolant
temperatures below 180 deg. F (82 deg. C), the thermostat valves remain closed and block the main flow path to the
radiator. The engine-driven water pump circulates coolant through the oil cooler and engine and through to the radiator
top tank via the deaeration line. From the top tank the coolant is returned to the water pump via the fill line. Thus the
warm coolant is vented and circulated without heat loss in the radiator core. When the coolant temperature increases to
180 deg. F (82 deg. C), the thermostats start to open and at the same time restrict the by-pass system. The partially
open thermostats permit a portion of the coolant to circulate through the radiator. When the coolant temperature reaches
approximately 190 deg. F (88 deg. C) the thermostats fully open, the by-pass system is completely blocked off and all of
the coolant circulates through the radiator. The engine coolant temperature is registered on temperature gages located
in the cab and on the structural control panel.
Figure 1-22. Engine Cooling System