75
Fig.118
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14
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. Engine cooling system
1)
Description for cooling system
The cooling system is of pressure system. It includes water pump
driven by timing belt, crosscurrent radiator, expansion tank, pressure cap, thermostat and electric fan, fan
shroud.
When engine coolant temperature is low, water pump draws the coolant in the left water room of radiator
and pump it to the cylinder block, cylinder head and intake manifold after pressurizing, going from the
local circulation pipe of the thermostat seat to the warm air heat exchanger, and then from heat exchanger
back to water pump inlet. The coolant back from intake manifold joins the heat exchanger and then backs
to water pump inlet. When engine coolant temperature reaches the point for thermostat to open, the coolant
for cooling cylinder block, going through the opened thermostat, combusting chamber and behind the valve
seat, will go into the right water room of radiator from the drain pipe of thermostat seat. For being cooled
by electric fan blowing, the coolant is already cooled When it reaches the left water room,.
When engine works under normal working temperature, coolant will expand. So the relief valve in the
thermostat seat opens. The coolant enters the expansion tank from overflow tube. After the system is
cooled, the coolant comes back to the inlet of water pump from expansion tank.
The electric fan operation is controlled by thermo switch installed in the right water room of radiator.
When the contact point of thermo switch closes, the electric fan operates. Water temperature sensor is at
the back of the cylinder head at exhaust pipe side.
