Ask the Mechanic

Keep the Thermostat

(Getty Images, Photo illustration by Barry Falkner)

READER: My 350 V8 Chevy grain truck has an overheating problem. It seems to run cool when back from the elevator but tends to want to overheat when going to the elevator when loaded. The guy in front of me at the elevator told me that I might try removing the thermostat to help with this problem. Do you think a new thermostat will solve the problem, or do you think I should just take it out and throw it away?

STEVE: I would like to see you wash out your radiator on the outside, flush the inside and check your fan belt for slippage before you do anything else. Then, if the problem still exists, change the thermostat out, and don't forget to get a new gasket with it.

If it still gets hot, I suggest a new radiator unless you can find a radiator shop, which is difficult these days because of the environmental concerns with those businesses.

Many times, the importance of a thermostat is overlooked. This little guy regulates the coolant temperature in the engine, improves engine warm-up time and can improve engine performance. Newer engines of today run warmer, which helps with emissions.

The thermostat contains a wax element that is thermally sensitive; it expands a valve when it's heated and closes when cooled.

Most thermostat problems are caused from poor coolant maintenance. The coolant should be changed every five years or what is recommended by the manufacturer. Also, be careful when mixing coolants. Be sure they have the same ingredients; otherwise, you chance a mixture that can cause corrosion in the cooling system. If you are not sure, drain the system and fill with the same coolant.


-- Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email, and be sure to include your phone number.


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