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Occasional Visitor
WJMMCO
Posts: 2
Registered: ‎05-09-2012

1999 Cadillac DeVille with 55K miles overheating

This is a recent problem. There is Dex Cool in the system. A/C doesn't work but no A/C last year and no temp problem. Short distances OK and then starts to overheat - goes above the fan turn on of 222. Lose little or no water - no more than a quart and this amount shouldn't cause overheating. Took in and Water Pump, Thermostat and fan belt replaced. Also did Flush (which should have picked up any blockage) and Pressure Check (which should have picked up any leaks). Did not solve so took back and they replaced a hose spring clamp with a screw clamp. Did not solve and took back again, They said they ran it for 4 hours and took it for a ride (probably short distance and low speed). They said no problems experienced. Got the car back and same problem. Appears problem happens quicker at higher speeds. When temp starts rising,,lower speeds and stops (at lights) reduce the temp but still too high. There is a significant amount of info on the net about this issue but nothing specific. Head gaskets and purge line clog are mentioned. There is also a class action lawsuit on this problem. They are asking us to bring it back but they don't have anything specific in mind. They only charged for the first repair. We checked with another shop that says they have a mechanic with Northstar knowledge. But they said they will charge $98/hr and don't know how many hours to identify the problem and there would be a repair cost after that, If we knew the final cost we could then decide the best course of action.

Honored Contributor
AAAPete
Posts: 1,273
Registered: ‎09-02-2009

I would have your technician run a block test to check fo...

I would have your technician run a block test to check for the presence of exhaust gases in the cooling system. If exhaust gases are found to be present I would then suspect head gasket or cylinder head issues. This may not make itself evident when the engine is first started so the check may need to be done when hot.

Occasional Advisor
AJS427
Posts: 5
Registered: ‎05-09-2012

northstar over heating condition

Change the radiator cap first

Occasional Visitor
WJMMCO
Posts: 2
Registered: ‎05-09-2012

Cap changed twice..One with a latch that pressure seals a...

Cap changed twice..One with a latch that pressure seals after twisting on. The other a direct replacement of the original cap. Both are 16 pounds.