Thermostat: Service and Repair

Fig. 17 Engine Thermostat:

NOTE: The thermostat is located in a water box, formed in the timing belt end of the intake manifold. This thermostat has an air bleed valve, located in the thermostat flange. It is designed to provide the fastest warm up possible by preventing leakage through it and to guarantee a minimum engine operating temperature of 88 to 93°C (192 to 199°F). They also automatically reach wide open so they do not restrict flow to the radiator as temperature of the coolant rises in hot weather to around 104°C (220°F). Above this temperature the coolant temperature is controlled by the radiator, fan, and ambient temperature, not the thermostat.


REMOVAL
1. Drain cooling system down to thermostat level or below.
2. Remove thermostat housing bolts and housing.
3. Remove thermostat, discard gasket and clean both gasket sealing surfaces.

Fig. 18 Engine Thermostat Installed:

INSTALLATION
Center thermostat in water box pocket. Check that the flange is seated correctly in the countersunk portion of the intake manifold water box. Install new gasket on water box. Install housing over gasket and thermostat and torque bolts to 12 Nm (133 in. lbs.)