over heatin

89Mj · Jan 26, 2005

hey first i would like to say sorry for my spelling but need some help my 89 4.oL MJ over heats when wheelin anything over 20km it is fine but when drivein under 20 for about 5min it will over heat tryed flushing out the coolint system new stat and there is nothin in the rad finns its clean someone told me to stick a 1/2'' news paper in the fan when runing and if it stoped the fan then the cluch is no good but it did not stop the fan just riped though it any help would be great thanx

BigDadys94xj · Jan 26, 2005

my 87' did the same thing first I replaced the cap on the pressure tank that worked for a while then it started again I found a tiny crack in the pressure tank . I replaced it and its been fine ever since. I would try changing the cap first then go from there .(ALWAYS TRY THE SIMPLE S##T FIRST)

xjoe · Jan 26, 2005

I have know several people who have had overheating problems.the biggest culprit so far is a faulty clutch fan.My 87 cherokee ran a little warm when i first bought it. So i had the radiator pressure tested, it failed as it it had small leaks and was only flowing at 45%. the closed system is not very tollerant of any leaks.I agree that you should start w/ simple stuff cap,hoses it never hurts to replace that kind of stuff on older vehicles anyway. I can't swear to it,but if you do a search (i think mad xj ) you might find some info on swapping in a later model radiator (open style) or converting your current system to the open style.

Eagle · Jan 26, 2005

If it heats up at idle and low speeds, and cools down again when you start moving again, the usual culprit is the fan clutch. They are difficult (or impossible) to test with any accyuracy. In general, if it is more than 5 years old it's time to replace it.

cykaaro · Jan 26, 2005

BigDadys94xj said:
my 87' did the same thing first I replaced the cap on the pressure tank that worked for a while then it started again I found a tiny crack in the pressure tank . I replaced it and its been fine ever since. I would try changing the cap first then go from there .(ALWAYS TRY THE SIMPLE S##T FIRST)

or simply put KISS!! [keep it simple stupid] Always the way to go when trouble-shooting.

Pete M · Jan 27, 2005

Chalk up another vote for the fan clutch (that is, if there aren't any coolant leaks). I know mine is bad. The truck likes to overheat at slow speeds on warm days. Fortunately, I have the auxilery electric fan (that I turn on manually now since the temp sensor or relay or *soimething* decided to die on me on the sand dunes). When the electric fan is on, there are no heating problems.
Jeep on!
--Pete

ComancheClub.com

89Mj · Jan 27, 2005

Thanx for the info guys it must be the fan i allready repleased the presor tank and cap would it be better to get a new fan or just put a eletric fan in beside the cluch fan and hook it to a tolge shiwch

Pete M · Jan 27, 2005

I would do both, but do the clutch first. You need to know that that was the problem so you don't end up masking the original problem with the electric.
Jeep on!
--Pete

ComancheClub.com

ChipsXJ · Jan 30, 2005

xjoe said:
I have know several people who have had overheating problems.the biggest culprit so far is a faulty clutch fan.My 87 cherokee ran a little warm when i first bought it. So i had the radiator pressure tested, it failed as it it had small leaks and was only flowing at 45%. the closed system is not very tollerant of any leaks.I agree that you should start w/ simple stuff cap,hoses it never hurts to replace that kind of stuff on older vehicles anyway. I can't swear to it,but if you do a search (i think mad xj ) you might find some info on swapping in a later model radiator (open style) or converting your current system to the open style.

what years have the closed systems?
what years have the open systems?

thanks

sjx40250 · Jan 30, 2005

Closed until 91.

over heatin

89Mj

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BigDadys94xj

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xjoe

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Eagle

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cykaaro

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Pete M

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89Mj

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Pete M

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ChipsXJ

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sjx40250

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