Question about 1998 Cadillac DeVille

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1998 cadillac deville overheating

My husband has a 1998 Deville w/ Northstar engine. He has been experiencing problems with the car overheating. He had the headgaskets replaced Sept. 2008. He has replaced the hoses and the thermostat. But has had to put more and more coolent to replace the coolent. He has not idea what is going on. today we drove on the interstate and the coolent temp went as high as 263 degrees. When we stopped the car, you could smell the coolent but have no idea where it has gone. can you help me please?

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  • cdcarter318 Jun 29, 2009

    initially he did, had a mechanic look at it and the mechanic could not find any leaks. problem persisted and so he decided to change out the hoses. problem still is going on. i am praying it is not the head gasket, since we paid a pretty penny fixing that Aug 2008.

  • Greg Bernett
    Greg Bernett May 11, 2010

    Dumb question but, have you noticed ANY leakes?



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Check for coolant in the oil. The oil will look like chocolate milk. After it's sat overnight you can also try loosening your oil drain plug until fluid comes out. See if it looks like chocolate milk or is just straight coolant. Check your spark plugs. Pull them out of the cylinder head and check for white corrosion or actual coolant in chambers or threads. You can also do a block test (rent the block tester at Autozone for $25.00- return when you're done and you get the $25.00 back) the block test fluid is $8.99. Follow the directions and if your test fluid turns green or yellow you have combustion/emission gases in the coolant. This can be caused by a cracked block/ cylinder head/ blown head gasket. You can also disconnect one head's spark plugs and test that cylinder then the other to see if only one is causing the problem. Hope this helps. If you're losing coolant, it's probably not your water pump. A lot of times if a head gasket fails, the head (usually made from Aluminum) will crack or warp.

Posted on Jun 29, 2009

  • Joseph Weisenberger
    Joseph Weisenberger Jun 29, 2009

    Has the block check been done since the repair?

  • Joseph Weisenberger
    Joseph Weisenberger Jun 29, 2009

    Coolant temp at 263 isn't terribly uncommon, unless it's not cooling back down again. You can be losing coolant because it is turning into steam and evaporating. Have you had your cooling system flushed or back (reverse) flushed? You might have some blockage in your radiator or heater core. How well does your heat function?


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I would have to agree with gypsycat00
test your block . as for the coolent vanishing thats easy once your temp hits 260 the coolent cap opens releasing all of that coolent though the over flow hose on to the ground leaving that smell !! so by the time you stop you usualy wonte find any leaks.
also till you do fix the problem try turning on the ac on low, now i no that sounds crazy but what that does is automaticly kick your fans on high even when first starting when the car is cold this will alow a longer drive before over heat and will some times keep from getting hot all together !! you should pulover before 246 to keep from dumping coolent, plus it will cool faster if you do !!
make shure you have the right coolent as the wrong type can cause faster overheating if its green its wrong, Cadillacs run hotter than many car so it requires dleco coolent which is orange and is made for GM cars which cadillac is made by GOOD LUCK !

Posted on Aug 01, 2009

  • steveneddy Dec 13, 2010

    Modern cars and trucks do not spill the coolant onto the ground - it is caught in a tank for reuse when the vehicle cools back down.

    These vehicles are prone to cylinder head cracks and warpage. It is a common problem and very expensive to repair.

    My advise is to either repair the vehicle and sell it immediately or sell the vehicle as is and take your losses. You aren't going to win in either situation.

    Cadillacs do not run hotter than any other vehicle out on the road today. This vehicle is simply prone to issues due to poor design.

    Dump the car and get a Chevy, GMC or Cadillac late model four door truck. You'll be much happier.



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