# Temperature gauge reads hot when the engine is not overheating



## tg442 (Jul 13, 2010)

I have a obd1 aba engine that says its overheating when it is not. I changed the waterpump a month/500 miles ago and did a full coolant flush. I already changed the coolant temp sensor but I feel like that has only made it worse. The temp gauge will rise as the engine warms up sometimes it stops at 190 and slowly rises to 230 sometimes it goes straight to 230. After warming up for a little bit I check the hoses and the thermostat hasn't even opened because the hose before it is hot and after is cold. When the thermostat opens the gauge either goes back to 190 only to rise to 230 again or just stays at 230. I know for sure the engine isn't overheating because the gauge will say its well past 230 but the engine is barely even warm and there's no other signs of overheating. Is it possible that another faulty coolant temp sensor could be doing this?


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## Anony00GT (Mar 6, 2002)

Do you have good heat? Does temp go down when heat is put on full blast?

Use an IR temp gun to verify actual temps. Could be a sticky thermostat and the engine is actually running hot but lower hose is still cold.


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## tg442 (Jul 13, 2010)

The heat works perfectly. When I turn the heat on all the way it has no effect on the temperature. Also I can feel when the thermostat opens because the hose will get warm but the temperature gauge stays wherever it was pegged to.


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## germancarnut51 (Mar 23, 2008)

Have you tried replacing the temperature sensor?


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## tg442 (Jul 13, 2010)

Yeah that was the first thing I replaced. I think it might me the thermostat now so I'm trying to replace that but it's such a pain in the ass.


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## tg442 (Jul 13, 2010)

Took the thermostat out and tested it in boiling water and its fine. I just changed my waterpump a month ago but my car still overheats. The fan doesn't come on when the car warms up so I used a paper clip to jump the fan at the thermoswitch by the radiator and it turned on. Can an air bubble in my cooling system be causing this? I tried to get all the air out do I just have to leave the cap off over night and hope for the best?


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## Anony00GT (Mar 6, 2002)

tg442 said:


> Took the thermostat out and tested it in boiling water and its fine. I just changed my waterpump a month ago but my car still overheats. The fan doesn't come on when the car warms up so I used a paper clip to jump the fan at the thermoswitch by the radiator and it turned on. Can an air bubble in my cooling system be causing this? I tried to get all the air out do I just have to leave the cap off over night and hope for the best?


Yes an air pocket certainly could cause it. Sometimes these cars are a real pain to burp.

Leaving the cap off overnight is a good idea.


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