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  1. #1
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    Default Upper hose sucked shut.

    I am having a major cooling problem. My upper hose is sucking shut after I turn the car off and it sits for a little time.

    This started happened about two weeks ago. Since then I have put in a new 185 degree thermostat (turns out my old one was 160??), new upper hose with a spring inside it, new 15lb cap, and I even had my griffin radiator tested and repaired (they reinforced a core and added some extra epoxy around a small possible leak). After puting in all new coolant I drove it around and it was getting hotter than it usually does (im guessing this is b/c of the higher thermostat?). I brought it back to the house and parked it. The upper hose was very hot...and the lower hose was warm to the touch. Fan works fine. I walked away for about 30 minutes to let it cool and came back. Both hose's were fine (upper with a spring and lower is copper cool flex) so I took off the cap. WOW!!! That thing just didnt want to come off!! Tthere was so much vaccuum in the radiator that it actually sucked off the rubber ring on the cap while I was taking it off. That is just not normal. What could cause this??

    Doug

    Douglas Lutes
    1988 Monte Carlo SS

    "Never race anything you can't afford to set on fire and push off a cliff."


  2. #2
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    Is the correct cap on the radiator ??
    Does the cap allow pressure to bleed off into an overflow container ?
    Like the factory set-up ??
    Maybe the cap is wrong for the application and is not allowing pressure to bleed off and then go back down.
    The overflow should flow in both directions.
    Do you have a massive air bubble trapped in the system ??
    Jeff Tate
    U.S.A.

  3. #3
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    the cap is correct.

    How should I go about bleeding the system of any air?

    some people online think I should drill a small hole in the thermostat.
    Douglas Lutes
    1988 Monte Carlo SS

    "Never race anything you can't afford to set on fire and push off a cliff."

  4. #4
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    Hmmm,
    I was just thinking that trapped air would cause a vacuum when it cooled down.
    Liquid would not cause a vacuum as easily ???
    (I'm not sure about this)
    Is this a first gen smallblock Chevy ??

    I always fill my engine up with coolant ( when it's cold ) , with the thermostat completely out of the engine.
    And with the thermostat housing ( gooseneck off the car )
    So , you're looking into the top of the intake manifold cooling passage. (An empty hole where the thermostat should go. )
    Just fill it up till it gets to the top.
    Let it sit a while.
    Then put the thermostat , gasket , gooseneck , and upper hose on.
    Then , fill it the rest of the way up in the radiator.

    You can drill a small hole or two in the thermostat.
    That will let the air out while its filling up too.

    I'm not sure that air in the syatem is your problem though
    Last edited by JEFFTATE; 05-11-2009 at 01:24 PM.
    Jeff Tate
    U.S.A.

  5. #5
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    Default

    I've always drilled 2) 1/8" holes in thermostats to pass any bubbles.

  6. #6
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    Any specific location in the thermostat where one should drill the holes? photo?

  7. #7
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    it is a gen 1 sbc.

    what about taking the thermostat out?
    Douglas Lutes
    1988 Monte Carlo SS

    "Never race anything you can't afford to set on fire and push off a cliff."

  8. #8
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    Default

    Quote Originally Posted by slowcamaro View Post
    Any specific location in the thermostat where one should drill the holes? photo?
    In the flat area, across from each other. I'd always run a stat otherwise you'll never get up to operating temp on a cool day.

    I've heard of the lower hose collapsing in on itself while running, but never the upper one.

  9. #9
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    Default

    Doesn't the water leave the engine via the upper hose and enter the engine via the lower hose...therefore the sucking should be at the lower hose?

    I can't think of a reason why the upper hose would suck shut like that.

    When you drill a hole in the thermostate, you only need a 1/8" hole and you mount the thermostat back in with the hole at the 12 o'clock position. The main reason to drill the hole is to help bleed the system and to allow some flow through thermostat so water pressure doesn't build up in the block when it's not open.
    Dan

    1968 Camaro RS - Black
    408 w/ Muncie 4 speed & 12 bolt rear
    Deluxe Houndstooth Interior
    Team III MiniLite Wheels


  10. #10
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    Didnt happen to drop the new thermostat into place upside down did you?

    Maybe the new stat is bad? Boil it in water to check it.

    Jack the front of the car up in the air to assure radiator is the high point of the system when burping the cooling system.

  11. #11
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    I've had this happen on 2 different cars. In both cases the return valve on the cap became plugged and wouldn't let coolant come back from the overflow bottle. It's the center silver on the bottom of the cap.
    Both cars had slight coolant leaks and stop leak was added. The stop leak was blocking the return valve. I was able to clean one cap with carb cleaner but the other had to be replaced. Just another possible thing to check.
    Randy Pajer
    79 GMC C35 Dually - truck stuff
    81 Camaro - CP car
    99 Bonneville SLE - DD

  12. #12
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    Quote Originally Posted by Randy67 View Post
    I've had this happen on 2 different cars. In both cases the return valve on the cap became plugged and wouldn't let coolant come back from the overflow bottle. It's the center silver on the bottom of the cap.
    Both cars had slight coolant leaks and stop leak was added. The stop leak was blocking the return valve. I was able to clean one cap with carb cleaner but the other had to be replaced. Just another possible thing to check.

    Funny thing you mentioned stop leak. I put in some of the Bars Leak Liquid ALuminum stop leak about two weeks ago. Turns out that it solidified in my overflow tank and was blocking it. It took me over an hour to get all of it out!! Now it is all flushed out and working properly and I am going to take it for as test drive later tonight. I am never going to use that stuff again!!!!!!!!
    Douglas Lutes
    1988 Monte Carlo SS

    "Never race anything you can't afford to set on fire and push off a cliff."

  13. #13
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    Quote Originally Posted by SicMonte View Post
    Funny thing you mentioned stop leak. I put in some of the Bars Leak Liquid ALuminum stop leak about two weeks ago. Turns out that it solidified in my overflow tank and was blocking it. It took me over an hour to get all of it out!! Now it is all flushed out and working properly and I am going to take it for as test drive later tonight. I am never going to use that stuff again!!!!!!!!
    So test drive by my way and finish my damned car for me!! I've been too busy on house stuff to work on it as of late.

    Glad you found your problem!

    Shiny Side Up!
    Bill
    Bill Kistner
    Check out my blog and the latest installment of my current project "In the Company of Devils" at: www.WilliamKElliott.com.

  14. #14
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    Quote Originally Posted by SicMonte View Post
    Funny thing you mentioned stop leak. I put in some of the Bars Leak Liquid ALuminum stop leak about two weeks ago. Turns out that it solidified in my overflow tank and was blocking it. It took me over an hour to get all of it out!! Now it is all flushed out and working properly and I am going to take it for as test drive later tonight. I am never going to use that stuff again!!!!!!!!
    Ah Ha !
    So the overflow wasn't working correctly.

    Glad you got it fixed.
    Jeff Tate
    U.S.A.

  15. #15
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    Quote Originally Posted by SicMonte View Post
    Funny thing you mentioned stop leak. I put in some of the Bars Leak Liquid ALuminum stop leak about two weeks ago. Turns out that it solidified in my overflow tank and was blocking it. It took me over an hour to get all of it out!! Now it is all flushed out and working properly and I am going to take it for as test drive later tonight. I am never going to use that stuff again!!!!!!!!
    haha, I told you that you had a blockage somewhere on the 11th!!

    I had a blast this weekend at the cruise man, can't wait for October!



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