Thermostat: Service and Repair

COMPONENTS

DISASSEMBLY
1. Drain the coolant down to thermostat level or below.
2. Remove the engine coolant outlet fitting and gasket.
3. Remove the thermostat.

INSPECTION





1. Heat the thermostat as shown in the illustration.
2. Check to see if the valve operates properly.
3. Determine the temperature at which the valve begins to open.

Valve opening temperature: 86.5 - 89.5°C ( 187.7 - 193.1°F)
Full opening temperature 100°C (212°F)

Thermo Sensor A (On Radiator)








Check for continuity with the thermo sensor in hot Engine coolant.

NOTE: Immerse thermo sensor in hot Engine coolant up to the mounting threads to check for continuity.

Operating temperature [NORMAL OPEN TYPE]:
OFF -> ON: 87 - 930°C (189 - 199°F)
ON -> OFF: 83°C or more (189 - 199°F)

Thermo Sensor B (On Radiator)








Operating temperature [NORMAL OPEN TYPE]:
OFF -> ON: 97 - 103°C (207 - 217°F)
ON -> OFF: 93°C or more (199°F)

Thermo Sensor (On Engine coolant outlet fitting)








Operating temperature [NORMAL CLOSE TYPE]:
OFF -> ON: 108°C or more (226°F)
ON -> OFF: 112 - 118°C (234 - 244°F)

REASSEMBLY
1. Check to ensure that the flange of the thermostat is correctly seated in the socket of the thermostat housing. If the thermostat is installed in the wrong direction, the bottom of the thermostat will touch the rib inside the intake manifold, making it impossible to seat flange in position.
2. Install a new gasket and engine coolant outlet fitting bolt

Tightening torque:
Engine coolant outlet fitting bolt: 17 - 20 Nm (170 - 200 kgs.cm, 12 - 14 ft. lbs.)

3. Refill the coolant