I have a 1989 Cadillac Sedan Deville 4.5L V8. This is where I'm lost, It does not over heat until i sit in traffic for longer than 10 mins. but at night or when its cold outside it has no problem.

Asked by GuruDFJXT Oct 17, 2017 at 11:57 AM about the 1989 Cadillac DeVille Sedan FWD

Question type: Maintenance & Repair

Anyway, I dont understand why if it's warm outside and im in traffic it overheats
but when its cold outside or night time and im in the same traffic she runs fine.
I'm not sure if it's the thermostat or what. I don't have a lot of money to throw at
finding the problem but gosh darn it im about to finish school to be an aviation
mechanic and i feel like i should be able to figure this out. HELP.

7 Answers

Yes the fans are working. That was the first thing i checked. Could it be that i need to replace the radiator?.....i hope not...thermostats are cheaper....

22,660

Yes the radiator might not be dissipating heat as well. It could be plugged up and full of gunk. A thermostat or temperature sensor might be the culprit. Both the sensor and thermostat are testable.

how do i test them? I'm not sure how old the coolant is. I know i had to add some to what was there the first time it broke down back in late august.

22,660

Go on YouTube and search for the tests. I could explain it but I would probably confuse you with industry jargon. I was also thinking you have a leak if you are adding coolant. You should never have to add unless you are draining and refilling. A car should not use coolant. You need to pressure test system for leaks. A car will overheat that does not hold the recommended pressure for your make and model.

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