1999 northstar warped heads

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Northstar Engines and System Technical Discussion Discussion, 1999 northstar warped heads in Cadillac Engine Discussion; I had two occasions of overheated coolant and stopped the engine and let it cool. In both cases I was ...
  1. #1
    oldsmokee is offline Cadillac Owners Member
    Automobile(s): Cadillac 1999 sedan deville
    Join Date
    Apr 2008
    san antonio tx

    Unhappy1999 northstar warped heads

    I had two occasions of overheated coolant and stopped the engine and let it cool. In both cases I was able to restart and the first time I got about 1500 miles before it happened again. This time I went about 5 miles to a repair shop.

    It had been experiencing coolant loss prior to these episodes and the same repair shop had no success finding the cause of the coolant loss. Pressure tests were fine, they said. Also there was no stains showing coolant or oil leaking in the drive way.

    This time, the same thing, they couldn't find anything and I told them to do a compression test and check the codes. The compression test was ok. They found an oil leak around the oil pressure gauge and replaced it. Upon further testing they found that the pressure cap was faulty and replaced it. They took it out for a test drive and it overheated. Now they tell me the heads are "cracked" and will need to be repaired. The guy states that putting in the new pressure cap caused an increase in pressure such that it caused an increase in the size of the leak to a very large leak. He also stated that the compression test would not have found the bad heads.

    Any comments would be appreciated.

    Smokey in San Antonio.

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  3. #2
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Woodstock Ill.

    Re: 1999 northstar warped heads

    Cracked heads are almost never heard of. A "compression test" would not show a bad head gasket, but a "cylinder pressure test" would. Any decent mechanic should know the difference. How does he know that the head is cracked. Have they been removed and inspected?

  4. #3
    zonie77 is offline Cadillac Owners Connoisseur
    Automobile(s): 94 ETC,97 STS
    Join Date
    Sep 2003

    Re: 1999 northstar warped heads

    It is rare to crack N* heads. You should find a mechanic that is familiar with Northstars. I know that isn't that easy.

    Most newer cars have longer lives than old cars. Head gaskets are not that unusual of a problem.

    A compression test usually doesn't show HG's. A new cap doesn't make a bigger leak either.

    I concur with Ranger.

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  6. #4
    lenny lincoln is offline Cadillac Owners Fanatic
    Automobile(s): Cadillac
    Join Date
    Apr 2007

    Re: 1999 northstar warped heads

    3k head gasket repair is in order. Good luck. Please dont sell this car to another without informing them.

  7. #5
    stoveguyy is offline Cadillac Owners Connoisseur
    Automobile(s): 03 STS
    Join Date
    Aug 2007
    mpls mn

    Re: 1999 northstar warped heads

    at least find a shop that has done northstar repair. than your chances are better for a proper repair if they tear into the motor.

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