4-6
THEORY OF OPERATION
4
Thermostat
See Figure 4-4.
Figure 4-4
The cooling system thermostat (1) is contained in the
thermostat housing located on the rear of the cylinder
head. The thermostat controls the flow of coolant through
the engine. The thermostat is in the closed position when
the engine is cold. When coolant temperature reaches
190° F (88° C) the thermostat begins to open, allowing
coolant to circulate. The thermostat opens fully when
coolant temperature reaches 205° F (96° C), allowing full
coolant system circulation. As engine load is varied, the
thermostat will vary its open or closed percentage to
maintain the engine in an optimum temperature range. A
jiggle pin is provided in the thermostat to aid in the
bleeding of the system when filling.
Water Pump
See Figure 4-5.
Figure 4-5
The engine is equipped with a belt-driven water pump (1)
driven from the crankshaft pulley. The water pump
circulates coolant throughout the entire cooling system.
The water pump is equipped with a “weep hole” for
indication of seal wear. The pump is serviceable as a unit
only.
TN0573
1
TN0747
1
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