What should I do now?
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Cadillac Seville / Cadillac Eldorado Forum Discussion, What should I do now? in Past Cadillac Vehicle Discussion; 98 Eldorado North * Ok, my problems have been going on for 3 weeks now. This all started with a ...
  1. #1
    dave_noffsinger is offline Cadillac Owners Member
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    What should I do now?

    98 Eldorado North *

    Ok, my problems have been going on for 3 weeks now. This all started with a coolant leak. To the point here, I've got a new upper and lower radiator hoses, water pump, water pump belt, gaskets, thermostat, pressure tank cap, and have flushed and filled the system probably 10 times now. I've also cleaned out the purge line and put the GM coolant supplement tabs in sevearl times as well since I've had to drain and refill it so much.

    All of the leaks are taken care of but my problem is overheating now. At idle it will stay right at the half way mark or just a hair line above which is normal. You can let the car sit and run for an hour like that. When it's running down the road however it will overheat quick.

    With the cap off and the car at an idle I can see air bubles coming up from time to time. At first I thought that this was air just purging out of the system but it's been filled for some time now and it's still getting air.

    So, is there anything else to check or do before I rule it as a head gasket?

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  3. #2
    SL1CK's Avatar
    SL1CK is offline Cadillac Owners Enthusiast
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    Re: What should I do now?

    Has to be a headgasket...

  4. #3
    White99SLS is offline Cadillac Owners Member
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    Re: What should I do now?

    You might have a big air pocket still within the cooling system, happened to me when I replaced the radiator in my cobra, I had to jack the car up on an angle and fill it so the air would come out, just a suggestion.......................

  5. #4
    dave_noffsinger is offline Cadillac Owners Member
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    Re: What should I do now?

    Quote Originally Posted by White99SLS
    You might have a big air pocket still within the cooling system, happened to me when I replaced the radiator in my cobra, I had to jack the car up on an angle and fill it so the air would come out, just a suggestion.......................
    At this point I'll try anything really. I have my fingers crossed that it's not the head gasket but everything at the moment is pointing that way.

    Thanks man,
    Dave

  6. #5
    dave_noffsinger is offline Cadillac Owners Member
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    Re: What should I do now?

    Just because I'm curious, how hard is it to change out the head gasket really? I've done them on other vechicles but from what I understand the N* is a real pain in the butt. What kind of special tools or whatever would I need?

    Dave

  7. #6
    SL1CK's Avatar
    SL1CK is offline Cadillac Owners Enthusiast
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    Re: What should I do now?


  8. #7
    AlBundy's Avatar
    AlBundy is offline Cadillac Owners Connoisseur
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    Re: What should I do now?

    You know I find this very strange. I read about alot of people who changed their coolant and then developed overheating problems afterwards. I was wondering should I start a thread about that. After reading this stuff I'm very hesitant toward changeing my own fluid. My coolant is a sturdy 202 all the time. I'm wondering maybe the people who have done this did it wrong or maybe something wasn't tightened right regardless it seems to me to be an issue that needs to be addressed.

  9. #8
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: What should I do now?

    Dave,
    I think it is time to run a cylinder pressure test to confirm or rule out head gaskets.

    Albundy,
    I changed the coolant on my '97 Deville and my daughters '99 SLS when she bought it a year ago without a single problem. If everything is in working order, there should be no problems. I would not hesitate to do it yourself. It's not rocket sience, don't let it scare you.

  10. #9
    Zorb750 is offline Cadillac Owners Connoisseur
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    Re: What should I do now?

    Try my powerbraking method to determing gasket integrity. Call it a "Powered" cylinder pressure test.

  11. #10
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    walterroc is offline Cadillac Owners Member
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    Re: What should I do now?

    Zorb750, What is the power braking method you mentioned

  12. #11
    Zorb750 is offline Cadillac Owners Connoisseur
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    Re: What should I do now?

    Ok... I've posted this several times before and it DOES work well. With the car cool and the cap off, with coolant at normal level (1.5-2" below neck) in tank, start the car and let it run for a minute or so. Once it has run for a minute or so, adjust coolant level (I'd just add water for this part) to be 1" below the tank neck, probably 8 ounces or so more than usual.

    With the hood open, get in the car, hold the brake down, put it in drive, and without letting the car move, smoothly apply throttle, running the engine against the brake up to 1400-1500 RPM (it'll be a little over 1/4 throttle probably). The idea is to build cylinder pressure, not boil your transmission fluid. Don't hold it like that for more than a couple seconds. You will probably see coolant bubble if your head gasket is bad. The idea with the brake is that you are building a higher cylinder pressure by putting a load on your engine, as compared to just reving it in Park or Neutral. You will really see coolant fly upward if your gasket is severely compromised, otherwise you will just have some bubbles and a little coolant spray out of the tank.

    Don't do this in your garage, and you may want to put some rags around the neck of the tank, just keep them out of the pulley on the steering pump.

    It should be noted that this IS a conclusive test for exhaust being forced into the cooling system if it is bad. It is not conclusive if nothing happens. You could still have a tiny leak if this doesn't bubble. It's REALLY unlikely though. If you want to be absolutely sure, have someone watch the tank for bubbles, standing next to the car not leaning over it, so in case the car somehow moved (unlikely I know) he will not be hit.

    The only way this could back up and bubble out without the gasket being bad or head cracked would be if your heater hoses are reversed or something is somehow flowing coolant backward through the system. The surge tank connects into a T into your heater line, which does not use a valve on the Northstar engine. Just remember to increase RPM smoothly to avoid pressure imbalances which could skew the test.

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