1. #1
    Join Date
    Apr 2007
    Colorado Springs

    Angry YJ overheating,HELP HELP HELP

    90 yj back together after four years everything seems to be fine except for an overheating problem, I've pulled all the hoses and flushed them to make sure some nothing was blocked i've flushed the radiator ,and block ,they all have good flow, pulled the WP and thermostat , flex fan for excellent air flow ,. this is a real bummer after all the work i've put in HELP ME PLEASE

  2. Re: YJ overheating,HELP HELP HELP

    sounds dumb, but could be your radiator cap or a loose belt

  3. #3

    Re: YJ overheating,HELP HELP HELP

    could be the cap I had the same prob and a new cap fixed it. the pressur relief spring in the cap was weak and it allway spewed steam, long story short i eventually lost water I thought it was a leak some where else. I replaced the cap out of desparation. that was it
    go to bed with an itchy butt... you are sure to wake up with stinky fingers

  4. #4

    Re: YJ overheating,HELP HELP HELP

    Did you just get a flex fan? Jeep fans turn the opposite way of many motors. make sure you got the right fan for the direction. I've seen it happen..

  5. #5

    Re: YJ overheating,HELP HELP HELP

    Mine was overheating due to the secondary effects of a major vacuum leak around my EGR, which didn't work anyway. After fixing that leak, resetting the fuel mixture, and resetting the timing, it works great.

    Just an after-thought. Aren't there 2 different water pumps that will fit the 4.2? One has a reverse rotation of the other.

  6. #6

    Re: YJ overheating,HELP HELP HELP

    Are you still using a fan shroud? Could be a bad water pump as well.

  7. #7
    Join Date
    Dec 2003

    Re: YJ overheating,HELP HELP HELP

    Hi JTHM - I noticed that you didn't mention replacement of the lower radiator hose. Anytime that you are at wits end with an overheating problem and have tried everything (EVERYTHING) in the book to correct and are sure all components are functioning properly, replace the possible culprit....the lower radiator hose. We all assume that since it isn't leaking fluid onto the ground that it is OK. Bull. The hoses usually are laminated. They have an inner "rubber coating", an outer "rubber coating" with a webbing inbetween. Think of it as an inner and outer hose together with that webbing layer between them. The lower radiator hose is the pressure side from the pump. What can happen over time is the inner hose can develop a break in it and water starts to work it's way between the "2 hoses" along the webbing and swelling occurs. This swelling (sometimes) can be noticed on the outside as the hose looks oversized, but with hot water pressurized between the 2 laminates, the inner part of the hose can close up on the inside and restict water flow...or stopping it completely, especially with a good sealing cap and high water temperature over time. You can take the hose off and it looks fine inside (with no water pressure closing it up) and there are no external leaks on the ground because the outer half of the hose is fine. Hoses are cheap but often neglected. Take two hoses and call me in the morning. LBR
    Plant the wheelie bars and let the games begin

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