Page 175 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Engine systems 159

Figure 2.151 Twin electric fans

Figure 2.152 Thermostat closed

Figure 2.153 Thermostat open

When the temperature of the coolant acting on the wax pellet reaches the
operating temperature, there is suffi cient heat to cause the wax to expand, press
on the pin, and force it out of the cup to open the valve. Coolant is then free to
fl ow through the valve.
The wax pellet must always be fi tted so that it sits on the hot side of the coolant
fl ow through the thermostat ( Fig. 2.154 ).
Some thermostat fl anges are fi tted with a small subvalve to allow air to fl ow through
the thermostat as the system is fi lled with coolant ( Fig. 2.155 ). This small valve must