Intermittent overheating of engine is tough to diagnose

Q. I read your recent column about the reasons an auto’s heater may not produce heat, and what to do about it. I have a problem and thought maybe you can help.

My engine keeps running in the hot part of my temperature gauge. I throw on the heater full blast, and pray. This happens within 10 minutes of my driving. The problem is this issue is intermittent.

There was a hole in my radiator and it was replaced, but the problem still happens. They thought maybe there was a bubble in the line after they refilled the new radiator with coolant, but it is still happening.

There is a small leak in my air conditioning, too. Could that cause this problem?

Do you have any suggestions for why this is still happening? I have a 1994 Dodge Spirit. I have taken good care of her, but like me, she is getting old.

I appreciate any help you can give me. I hate to send her out to pasture.

A. The air conditioning most likely has nothing to do with the overheating you describe. I have a lot of questions I would ask if you were standing in my shop.

Ÿ Now that it has gotten colder, does this still happen?

Ÿ Are there any other symptoms other than the temp gauge going high?

Ÿ When you notice the car running hot, how is the heater? Does the heated air get cooler?

Ÿ When the radiator failed, did the engine overheat badly?

Ÿ You say the problem is intermittent. Does that mean sometimes the car’s temperature seems totally normal?

How you answer these questions will help determine where we might look for the problem and what tests I would recommend. You did not say what engine you have, and that might make a difference, too!

From what information I do have, I am concerned you may have a bad head gasket or perhaps a water pump where the impeller is failing. There are some tests that a good diagnostic technician could perform that should be able to hone in on this problem.

I hope this helps and please let me know the outcome. Thanks for reading the column.

Ÿ Douglas Automotive is at 417 W. Main St., Barrington, (847) 381-0454, and 123 Virginia Road, Crystal Lake, (815) 356-0440. For information, visit douglasautomotive.com. Send questions to underthehood@dailyherald.com.