How can I test my thermostat?

(2010-10-21 02:10:07)

1. RunIt31 Says: You must remove the thermostat for testing.

First thing to look at is if the thermostat is cool but open the thermostat is bad. See my later comments about the fail safe design.

You will need a 2 quart pan, your stove, and a meat thermometer, or any thermometer that can be put in liquid and can read to 212F

Fill the pan with water and throw in your thermometer. Put the pan on the stove and turn the burner to high. Watch the thermometer and the thermostat. As the thermostat reaches its rated temperature you should see it open. This is usually somewhere around 180F - 210F. This will vary depending on the specific requirements of the engine.

Many modern automotive thermostats are what is called a fail safe design. This means that if they fail they will stick in the wide open position to protect the engine. Therefore the symptoms of a failed thermostat can be that the engine takes an unusually long time to reach operating temperature or the engine never comes to full operating temperature because the thermostat is stuck wide open.

However if you are going to all this much effort you may as well replace the thermostat as they are not all that expensive.

2. Mad Jack Says: to find out if it,s opening up , when the engine is hot then the top radiator hose should be too.