Operation CHARM: Car repair manuals for everyone.

Thermostat: Testing and Inspection

Thermostat Test

Replace the thermostat if it is in the stuck open position at room temperature.

To test a closed thermostat:

1. Suspend the thermostat (A) in a container of water. Do not let the thermometer (B) touch the bottom of the hot container.





2. Heat the water, and check the temperature with a thermometer. Check the temperature at where the thermostat first opens, and at where it is fully open.
3. Measure the lift height of the thermostat when it is fully open.

Standard Thermostat
Lift Height: Above 8.0 mm (0.31 in.)
Starts Opening: 169 - 176°F (76 - 80°C)
Fully Open: 194°F (90°C)