1. #1
    LeHul1's Avatar
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    my 98 xj 4.0 is running hot

    It had been running steady at 210 to 220. In the last few days it has been red lining once in a while. When I rev it up it comes down I also turn the heat on. I changed the thermostat to a 180 yesterday. Still runs hot, over heated once since. Any ideas. The top of the main fan shroud is broken off too...

  2. #2
    xjmarc's Avatar
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    Re: my 98 xj 4.0 is running hot

    Shroud will affect it but not much. I don't like the 180 t-stats mine seemed to loose power with it. Is the electric fan coming on and when you swapped the t-stat did you make sure to get all the air out of the system and have you checked the coolant level recently?

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    LeHul1's Avatar
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    Yes the fan(s) comes on. I have had five of these jeeps, and have got some air bound in the past but I believe we got it all out this time...yes the coolant levels are normal...any other ideas?

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    How old is the radiator and water pump? How long have you owned it? The previous owner may have ran it with just regular tap water wich corrodes things like thaw blades on the pump and inside the radiator.. I replaced min recently and I'm running a 192 tstat. My jeep runs at about 210 sometimes a little higher but never overheard.. that's where my 2 buddys jeeps run at as well.. but we are in hot weather Soo...

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    Re: my 98 xj 4.0 is running hot

    More then likely your head gasket is starting to go. I changed out my t stat to a 180 . And I have more power. But it your water pump is fine and nothing wrong with the radiator. Check your cap as well. It's the only thing left.just went ahead and did my head gasket. It was blown for awhile. Never overheated or came anywhere close.

  6. #6
    LeHul1's Avatar
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    Thanks y'all. The radiator is original. New water pump from previous owner. I pre the 180 in and the temp came down to normal and below once I burped it once by leaving cap off over night. Send ok more but I did notice alt of black sludge in over flow bottle. Next I am thinking a bottle of radiator flush and then run it hard for a day then flush it with garden hose real good. Yes it has been so hot out that the a/c is essential...soooo..thanks again boys..I'll be posting more for sure..this forum is great!

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    I had the same problem on my 99 and ended up being the water pump. There is a away to check it on the under side is a little ball bearing and once it starts to barely drip the pump is gone. I went to turbo city and got the high flow tstat housing and new tstat since opening it anyways and high flow pump. Flushed the radiator (I am running a 3 core all metal, not stock had this before heat issue). Fixed all the overheating issues.

    On a side note, for cooling I removed the clutch fan and added an additional factory a/c style to it. I had already gone through few junkyard fans and had a cheap parts store one catch fire. I knew the old clutch fan studs cause clearance issues but decided I will never go back to the clutch style. I put some lock tight on the nuts to keep pulley in place then cutting the studs flush to the 4 nuts. Bingo the factory style dropped right in and cleared. It's a strong fan and what's nice is not only does it have it's own shroud but the factory tabs on the bottom still locked in since that mount area is for LH drive or RH drive. Still haven't decided what wiring I'll end up doing but for now the stock one is still set to a/c and factory 217 kick on, new one is on adj. thermostat with relay to acc.

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    Question.. when driving my 97 xj in slower traffic it stays at an okay temp but once I hit about 60 after a while my temp goes higher than I like... How do I keep it cool under higher loads and higher speeds? I have an all aluminum 2core radiator that's brand new new water pump and new tstat

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    180 degree t stat. U won't lose power. I didn't . Actually gained some

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    My cousins running a 180. It runs at the same temp as mine driving down the highway

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    LeHul1's Avatar
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    97 xj, is the a/c coil in front of the radiator clean? Sometimes it will get stopped up with bugs and trash. You should be able to see through it completely.. Just an idea..

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    1sickXJ's Avatar
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    How hot is it getting? A lot past 210 or just a little

  13. #13
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    Yea it will run a little hotter on the highway. But overall it runs cooler. The cooler the motor the more mpg.

  14. #14
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    Re: my 98 xj 4.0 is running hot

    This is true, cooler = mpg but to cool can actually hurt you total performance too. Is your set-up all stock? You could always use a relay and adj. thermostat - tie into the a/c electric fan and have it come on at a lower temp before clutch fan ever actually engages. If you have the AW4 auto with trans cooler built in to radiator that trans likes to run hot. Hot trans fluid along with hot coolant going through a stock radiator (plastic, some are single core, few 2 core) is going to keep your temps up around std. operating regardless. Provide some details on set-up and we can go from there on ideas...

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    Re: my 98 xj 4.0 is running hot

    IF you are running hotter on the highway than in the city you have a fan issue. It can be countered by a lower thermostat but unless you primarily run lower vehicle speeds such as we do off road this is a false fix. Your fan is the problem. if its a mechanical belt driven fan the clutch is hanging and not free wheeling and the blades are acting to block air flow. if it's electric your motor may be starting to go bad. These are basic automotive facts that are often overlooked when dealing with off road vehicles that are driven at slower vehicle speeds with higher engine speeds.

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