Thermostat: Testing and Inspection

This test requires that the thermostat be removed from the vehicle.





1. Suspend the thermostat in a pan of 50/50 mixture of ethylene glycol and water. Do not let the thermostat (or thermometer) rest on the bottom of the pan because of the uneven concentration of heat at that part of the pan.
2. Place the pan on a burner; heat and measure the temperature of the solution using a thermometer.
3. The thermostat valve should begin to open (depending on whether it's a type A or type B) when the temperature reaches 88 to 92° C (190 to 197° F). When the temperature of the solution reaches 100 to 105° C (212 to 221° F) the valve should be fully open.
4. If the thermostat does not perform to these specifications, replace it with a new one.