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water woes

Discussion in 'Early CJ5 and CJ6 Tech' started by Monkey Wrench, Oct 1, 2008.

  1. Monkey Wrench

    Monkey Wrench Most junior member

    Here's the problem:

    Recently rebuilt motor (f134), rebuilt radiator (1 year ago), 7# cap.
    Everything is fine when running with cap removed (water is circulating). With cap tightened, pressure builds to either immeadiate overflow at bypass on tank or a water leak develops at the middle upper exhaust manifold stud (only if pressuure isn't released at overflow). Also no leak if cap is removed. Water temp. is approx. 160.

    Any help would be appreciated. Thanks.
     
    Monkey Wrench, Oct 1, 2008
    #1
  2. Posimoto

    Posimoto Hopeless JEEP Addict

    Sounds like that manifold stud needs sealant. I assume we're talking about a 4 banger. Pressure is a factor of heat. Check your actual water temp with a thermometer. Excessive pressure is a direct result of excessive temperature.
     
    Posimoto, Oct 1, 2008
    #2
  3. Monkey Wrench

    Monkey Wrench Most junior member

    I haven't checked the temp wth a thermometer but the water coming out of the overflow is not hot to the touch, only luke warm (would not burn your hand) and the overflow will occur if you tighten the cap as soon as you start it up, so it hasn't even become hot yet.
     
    Monkey Wrench, Oct 2, 2008
    #3
  4. w3srl

    w3srl All-around swell dude Staff Member

    Sounds like you could have a bad head gasket or a crack somewhere that is leaking cylinder pressure into the cooling system. When the cap is off and the engine running, do you see bubbles in the coolant?
     
    w3srl, Oct 2, 2008
    #4
  5. Monkey Wrench

    Monkey Wrench Most junior member

    The coolant in the radiator looks tubulent, like the water pump is moving it I had assumed, not like air bubbles persay, unless they are really tiny, I guess. I hadn't thought about a gasket leak though.
     
    Monkey Wrench, Oct 2, 2008
    #5
  6. Glenn

    Glenn Kinda grumpy old man Staff Member

    A cold engine shouldn't have any flow into the radiator, or very minimal, so the water shouldn't be turbulent. This is assuming you have a thermostat, of course. I'm with Steve, head gasket leak sounds likely.
     
    Last edited: Oct 2, 2008
    Glenn, Oct 2, 2008
    #6
  7. 53A1

    53A1 Member

    x2 on leaking exhaust stud.

    Before I would jump to conclusions that your head is cracked I would remove the exaust manifold, remove the stud, REPLACE WITH NEW STUD WHILE YOU HAVE IT OUT - $2 insurance, use some high temp thread sealant - NOT THREAD LOCK, and give her a go. On those engines the stud holes are a direct opening to the water cavity. Any leak in the system will cause high temp and boil over. Good luck trying to get the bolts off. Better soak'em with blaster first.
     
    53A1, Oct 2, 2008
    #7