a NEW overheating problem

    i have had ongoing overheating problems since i bought the XJ. when it wasn't occasionally overheating, it ran at a steady 210 (temp gauge at exactly 12:00). after my water pump seized and we installed a new Bosch one, the running temp went down about 15 degrees (gauge at about 11:30). i was quite pleased. i figured the water pump must have been bad for a while, operating poorly, then finally seized.


    THEN, i threw the belt last week after getting stuck in the mud.


    ever since, it has been running hotter than it was before the water pump replacement (gauge at about 12:30). plus, it's been frequently overheating with the temp gauge going into the red and the 'check gauges' light coming on.

    ~ JD
    * WARNING - The above post may contain trace elements of biting sarcasm. Those with known sensitivities should avoid staring directly at it.

    so today, i'll check the thermostat and the water pump.


    what confuses me is that the jeep now runs at two different temps - 220-ish (gauge at 12:30) and then shoots up to 235-ish (gauge at 1:00), then comes back down. no more, no less, nothing in between. as though there is some kind of temperature control happening.

    ~ JD
    * WARNING - The above post may contain trace elements of biting sarcasm. Those with known sensitivities should avoid staring directly at it.

    i had checked the coolant on friday, and it was fine. i just went outside and checked it now, and it was low - it took over 1/2 gallon. i didn't see any evidence of a leak, so maybe some of it had boiled over/off. the belt has a bit of a squeal again (just at startup), so maybe tightening it will help?


    how do i test the thermostat?

    ~ JD
    * WARNING - The above post may contain trace elements of biting sarcasm. Those with known sensitivities should avoid staring directly at it.

    Quote from Keith_C

    Drop it in a pot of boiling water and see if it opens.


    kinda like clams and mussels? :D

    ~ JD
    * WARNING - The above post may contain trace elements of biting sarcasm. Those with known sensitivities should avoid staring directly at it.

    Just replace the thermo it is like 5-8 buck. after replacing all my tubes and and getting the bubble out of the rad and then 2 different time flushing the system i finally change the thermo and bam problem solved. its the cheapest thing to replace and if your taking it out anyways... the 180 is the stock thermo and i have been told to only get that one unless you live in the desert or way up north in the extreme cold.



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    Quote from rstiles


    Just replace the thermo it is like 5-8 buck. its the cheapest thing to replace and if your taking it out anyways...


    good idea

    ~ JD
    * WARNING - The above post may contain trace elements of biting sarcasm. Those with known sensitivities should avoid staring directly at it.

    Quote from rstiles


    ...the 180 is the stock thermo and i have been told to only get that one unless you live in the desert or way up north in the extreme cold.


    i do believe that the stock thermostat is 195*. from what i have read, while it is not harmful to run cooler (it's certainly better than hotter), 195* is the optimal temp and operating at less than that reduces engine efficiency and performance.

    ~ JD
    * WARNING - The above post may contain trace elements of biting sarcasm. Those with known sensitivities should avoid staring directly at it.

    You said you were stuck in the mud. Did you take a hose and THOROUGHLY clean out the radiator and a/c condenser?

    You can also clear out air/cavitaion in the engine by bleeding out the air using the heater hose ports. Works like a charm with 4.0 and 258s.

    Nobody belongs anywhere, nobody exists on purpose, everybody's going to die. Have a beer.


    Jeeps Owned... 89YJ, 81CJ-8, 99XJ, 93XJ, 00WJ, 05LJ, 22Bronco Badlands !

    Quote from alextremetj


    You said you were stuck in the mud. Did you take a hose and THOROUGHLY clean out the radiator and a/c condenser?


    i have an industrial pressure-washer here at work. i used that. apparently not thoroughly enough, though. i was just outside looking at the jeep again, and mud can still be seen on the engine side of the radiator. i'm heading back out to blast the radiator again now - much more diligently this time.


    this is most likely the problem. :doh:

    ~ JD
    * WARNING - The above post may contain trace elements of biting sarcasm. Those with known sensitivities should avoid staring directly at it.

    Air pocket! no way is 1/2 gallon going to disapear. when you did the water pump you musthave not got all the air out. thats why it was flucuating. then when the air burbed out its all good. you must have not dont a good engough job at burping the air out.

    96 Jeep Grand Cherokee: <br />4.0L - 4.5&quot; Long Arm - D44&#039;s Locked - 33&quot; M/TR&#039;s <br />XRC 8K Winch - Daily Beater / Offroad Machine<br />1970 Chevy Nova: Rowdy Street Car

    I ran into a problem similar to this when I owned my '99. Result was a CSF three core radiator and 160 thermostat. The 160 was to low and my gas mileage dramatically decreased so I later put in a 180. Regardless of what I did it always ran around 200. Check you electric fans and make sure they're still functioning properly, but a couple bottle of simple green and soak the motor and/or cooling system down.

    &quot;Gun control is like trying to reduce drunk driving by making it tougher for sober people to own cars.&quot;

    Are you running straight antifreeze? or a mix?
    Water boils at 212. So if you are running a diluted solution you could be making steam, which would explain some of the fluid loss.
    Engineer in training perspective. ;D

    Quote from ScottsAlot


    Are you running straight antifreeze? or a mix?
    Water boils at 212. So if you are running a diluted solution you could be making steam, which would explain some of the fluid loss.
    Engineer in training perspective. ;D


    Don't forget that the cooling system is under pressure, so that raises the boiling point.



    It sounds like an air pocket to me as well.

    agreed. definitely sounds like air is in there. cause at 6 pound per square inch, the boiling temp rises to about 230 degrees F.

    Quote from deadfeat


    You can also clear out air/cavitaion in the engine by bleeding out the air using the heater hose ports.


    where are these?

    ~ JD
    * WARNING - The above post may contain trace elements of biting sarcasm. Those with known sensitivities should avoid staring directly at it.

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