2000 Dodge Ram 2000 Ram - Good heat only when moving

If coolant is checked okay, then yes suspect thermostat is sticking.

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Yes, you can test it before replacing it. Unfortunately, this still required removal of the thermostat. Below are testing procedures once removed.

Most thermostats are rated to open at 190 degrees farenheit. Get a pot of water heating on a stove, suspend the thermostat in the water by tying it to something that can hang across the top of the pot with some ordinary string, use a thermometer (one that can at least stand the boiling point of water which is 212 degrees farenheit). Put the thermometer in the water along with the setup and watch the temperature. At around 190 degrees, the thermostat should open up indicating that it operates normally. If not, then it is defective, or it is rated to open at a different temperature. There is usually a stamp or engravement at the butt of the thermostat that shows its temperature rating.

Want to save some green and do it yourself? Need replacement instructions for this component? Just ask and you shall receive!

Hope this helps.
Thanks for using 2carpros. Com!