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Northstar Engines and System Technical Discussion Discussion, Overheating?? in Cadillac Engine Discussion; I have a pink 1997 DeVille and it is overheating. We replaced the water pump and the thermostat and it ...
  1. #1
    PinkCadillac is offline Cadillac Owners Member
    Automobile(s): 1997 Pink Cadillac Deville
    Join Date
    Jul 2009


    I have a pink 1997 DeVille and it is overheating. We replaced the water pump and the thermostat and it stiil over heats. Also there is no fluid flowing through the motor, after:confused running it for about 20 mins the car got to almost 200 and I shut it off and opened the radiator cap and cold fluid came out and both hoses were cold. Some people tell me it's a blown head gasket others tell me it's not. Can you please help me?

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  3. #2
    Mark C's Avatar
    Mark C is offline Cadillac Owners Connoisseur
    Automobile(s): 1997 Seville STS, 2000 Seville STS
    Join Date
    Jul 2007

    Re: Overheating??

    200 degrees is fine. If the A/C is on the fans will both be running in slow, if the A/C is off the fans don't even come on until the temp reaches 224 degrees, and they switch to fast at 235. Don't ever pull the radiator cap off with the engine hot, quickest way to get a free ride to the hospital with 2nd degree burns.

    There is a small (3/8") or so line that runs from the water pump housing across the top of the engine over to the surge tank (where the radiator cap is). With the engine cold, take that line off the surge tank and stick it in the top of the tank where the radiator cap goes and start the car. It the line doesn't flow water continuously (a little at idle and alot as engine speed increases) you have a plug in that line that needs to be cleaned out. This line vents the water pump and if it gets plugged the water pump will get airbound and not pump water. If that line is clear and flowing water you need to get your coolant tested for hydrocarbons. NAPA sells a kit for about 50 bucks, or you can have it done at most radiator shops. It will tell you if you have any carbon monoxide in your antifreeze which is a sign your head gaskets are going.

  4. #3
    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: Overheating??

    You replaced the pump and thermostat for nothing. As Mark said, 200 is nothing. 205-215 are normal operating temperatures.

  5. #4
    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
    Automobile(s): 2002.5 F55 STS - 65500 miles, 2014 Explorer XLT FWD
    Join Date
    Feb 2006
    MD Eastern Shore, Kent Island

    Re: Overheating??

    The thermostat (original equipment - don't know about your new one) is set to begin opening at 188 and be fully open at 206. The engine will run all day at 193 - 206 with any A/C function, as the fans always run in slow when the A/C is commanded on. Read Mark C's post again, and note the fan speed command temperatures. Ranger is also on target, especially for a city car in hot weather.

    You're fooling with a quite different cooling system than meets the eye............and don't change to a "cold" thermostat !! The engine fuel and operating controls are set for the thermostat original temperatures.

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