Overheats when it is idle?

BUDDERS71

MEMBER
2000 CADILLAC DEVILLE
110,000 MILES

When I'm on the highway, the temp. Gauge reads normal and the heat works fine. When I slow down to a stop, the temp. Gauge goes up and and I start getting hot engine display on the dash and the heat blows out cool air. I get out to check the engine when it overheats and the top radiator hose is hot and the fans are running. What could be the issue I am having, and what should I do to repair this problem?

Saturday, March 3rd, 2012 AT 1:40 AM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

There are a number of things to check but the most likely thing that will cause this is a thermostat.

However, here are a couple of guides that will help with this issue:

https://www.2carpros.com/articles/symptoms-of-an-overheating-engine

https://www.2carpros.com/articles/replace-thermostat

Assuming the thermostat is not the issue then we need to move onto the head gasket.

I have seen many of these things overheat at idle only when the head gasket is starting to leak.

So, if it were me, I would just jump straight to this issue and check the head gasket using this guide:

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

Once we know this info we can go from there. However, I would make sure you use the chemical test when the engine is hot to ensure you test it when this is happening.

Thanks

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Tuesday, February 15th, 2022 AT 11:26 AM