Question about 1998 Cadillac DeVille

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98 Cadillac Northstar motor running hot in 30 min.

My cadillac is runnig hot after 30 min. the water is pushing out the purge valve.. My purge valve connects to tank , but not to the motor. Is that part of the issue? What is the normal temp. for the Northstr motor?

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  • mrsmith007 Apr 20, 2010

    Yes. After about 25 to 30 minute, car run hot and water run out overflow line. fan come on when ac is on, when i turn it off fan dont come. What is the normal temp for this car.

  • mrsmith007 Apr 20, 2010

    Yes I believe it is... The water is coming out of it after 30 min. of the car running hot.... Can you give any suggestions?

  • Mark Carrington
    Mark Carrington May 11, 2010

    What do you mean by "purge valve" ?........are you referring to the small rubber hose?

  • Bill Schilz
    Bill Schilz May 11, 2010

    Have you replaced the thermostat yet?

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The normal operating temperature for the Northstar engine is around 210 degrees.
The fans will not come on until the temp hits 225 degrees.

The thermostat in the northstar engine is located at the bottom radiator hose (unlike most conventional cooling systems).

The most common overheating problem with the Northstar engine is a blocked purge line(small hose).The purge line is designed to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank (not the cap) ,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.The hose goes in to the engine to a crossover and comes out the other side to near the thermostat housing,the blockage may be there.

If the other end of your purge line is not connected to anything then that is the problem......it must be reconnected otherwise the cooling system is not pressurized.

Posted on Apr 20, 2010

  • mvmvtalk41 Mar 10, 2011

    Hey guys... You are incredible!!!! I have a Cadillac Eldorado 1995 a appsolutely gorgeous ride. I was told about the purge line.... On my reservor tank top left where my coolant is suppose to be the small purge line runs out the side of tank between tank and fan belt and engine?? Well my line isnt connected to anything!! Everytime my engine flips out my coolant runs out onto the road. So I am constantly filling up coolant. Oh please help me my phone number is 1-416-434-0220 please call my name is Maria

  • mvmvtalk41 Mar 10, 2011

    I am so excited!!! A little history... I have replaced the rad, water pump, heater core, all hoses on top of engine, relays, thermostat, fan motor. My engine is really quiet and no smoke coming out of dual exhaust system. I appreciate all of your expert advice.
    Thanks
    Maria

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Sounds like your thermostat has failed and is stuck closed.
Your thermostat is located under a metal housing on the top of the engine. The upper radiator hose connects to this housing. To change the thermostat you basically need to drain the radiator after your engine is cold, disconnect the upper radiator hose from the engine, and remove the bolts from the small housing. replace the thermostat, and clean the surfaces on both sides and replace the gasket too. reinstall the housing, attach the hose, and refill the radiator. start the engine, warm it up and check for leaks, then re check the coolant level after the engine cools off again.


98 Cadillac Northstar motor running hot in 30 min. - 145cc26.jpg

Posted on Apr 20, 2010

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My cadillac devill got bubles coming out of my reserd tank went et gets temperature half way and my fans are working and the termostat is opening
Please help

Posted on Jun 03, 2011

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