Question about 1998 Cadillac DeVille

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98 Deville Northstar temp runs up to 240 when idle

Runs rough at startup then reaches temp around 198 and smoothes out and runs very nice. temp will run up when sitting for 5-10 min but when I go agian it comes down and runs fine. Service engine soon is on and Autozone cmptr reads elec temp sensor that I cant locate. I just bought it 2 weeks ago and it does have some white smoke that clears when it wams up so I dont know if it was condensation. It is losing about 1/2 gallon antifreeze per week. Do I have blown head gaskets? Will any leak stop work? Thank you.

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  • clipperjay2 Nov 26, 2008

    change the sensor

  • txboifrozt May 11, 2010

    Yes you do have a head gasket leak. It might not be severe right now, but the more you drive it the more it will get worse. I have a 96 deville with northstar, and same thing you describe is same problem i had. I thought it might be the radiator, or thermostat, or heater core stopped up and the water pump. Replaced all and the temp still ran up very high. Especially on the highway. If you do not run up to any degrees near 240, your crack is still very small. Some headgasket repairs in a bottle might work. But only temporary, but can buy you time to either sell it or repair it. Headgasket is a very costly job. At first on my car i would start it up, it would rumble a lil, kind of rough, then smooth out after a couple seconds. Overheat easily, coolant spilling out the overflow constantly, and a little bit of smoke out the tailpipe and a little drip. I do not recommend on trying to replace anythingelse. These are a one of a kind, very difficult engine. Most mechanics will not even atempt to fix a northstar. There very notorious for these problems, and so hard to tear into to fix. Now you can try some stuff called THERMAGASKET.. around 100$ but if it does not work you get your money back.. and other stuff in a bottle you can get at autozone with NanoTechnology it is cheaper and you get your money back also if it does not work.


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Yes it is headgasket. Mine had same problem. Yours might not be severe as of now, you can try these other solutions. THERMAGASKET... Which you can buy online, and get your money back if it does not work... And stuff in a bottle at Autozone Repair headgasket with NanoTechnology! I would try and sell it quick, because these engines are very costly to repair and most mechanics wont even attempt headgasket repair, and plus you have to TimeSert the block...

Posted on Aug 06, 2009

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Posted on Aug 11, 2010

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