Overheating issue

Good morning.

A compression test does not verify a bad head gasket.

The leak down test is what confirms it. That is a test that injects air into the cylinder and you watch the coolant level in the cooling system. If you have a bad head gasket, the level will rise during the test.

That is the test that needs to be done.

Roy

https://www.2carpros.com/articles/head-gasket-blown-test

Thanks for getting back with me. The dealer did the first test and told me it was fine and there was air in the line. Then they showed me the air release valve under the coolant jug and how to bleed the air out of the system. Then about a week later it ran hot again on the highway. So I take it back to the dealer and they did a second test. and again they said it was fine. They did tell me to go by the Yellow Cab Global antifreeze. About a week after having it home again it started running hot on the highways if you get up to 70. If I keep it at 55 to 60 it just runs a little warm and if I turn on the dual climate control then the temperature gauge goes back to normal. So is the test that you are talking about something they would have done the second time I went in or would I have to ask for it specifically?

I doubt it. They are missing the point. Air comes from somewhere. You should not have to bleed the system. The air could be coming from the head gasket leak.

They have not found the root cause of failure here at all. Surprised for a dealer.

Coolant type does not matter. The mixture does. It needs to be a 50-50 mix. One coolant will not make it run cooler than another.

Roy