overheating in a weird way

hey my 91 xj HO iis ovreheating on trails it will idle for hrs. OK run 210 at 90mph but uner 15mph for a while Bam 250. gotta pop the hood and let it cool this goes in 20min cycles pretty consistantly. dad just says that shows it doesnt need to be muddin so i tell him he is just getting old haha.

please help me out here It doesnt have any new coolant parrts so it could be anything

wheelchairman said:

hey my 91 xj HO iis ovreheating on trails it will idle for hrs. OK run 210 at 90mph but uner 15mph for a while Bam 250. gotta pop the hood and let it cool this goes in 20min cycles pretty consistantly. dad just says that shows it doesnt need to be muddin so i tell him he is just getting old haha.

please help me out here It doesnt have any new coolant parrts so it could be anything

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Sounds like a weak fan clutch.

well thats one thing i was thinkin it does sound like the aux. fan is kickin in but it still doesnt help much at all.


oh and to save the replies that just say " search is your friend" i did and all of them overheated over 70mph i saw nada about under 15mph

This is anything but weird, the reason you are not overheating when you are going 90 is because you have all the air from foward motion to cool the radiator. When you are idling you do not have enough air moving over the radiator. It sounds good that the aux fan is kicking in but that is only suplimentary, your fan cluch must be on its way out. I would say get a new one and give the cooling system a good flush.

Katarn

i had that happen on my 95. turns out my aux fan was kicking in, but upon further inspection i realized it wasn't going very hard. it died about a month later. i put in a new aux fan and it's been good every since.

i also removed my A/C system, and since taking out the condenser from in front of the radiator it droped the temp a little and runs very very steady.

Just last night I replaced my fan clutch (HD Torq Flo from Autozone) and t-stat (Prestone 330-195...equal to Robert Shaw hi-flow, got it at Checker). What a difference...By watching the gauge, I can actually tell when the t-stat opens. It drops from 212 to 200, then creeps up again. I really should pay more attention to the road

Before, I ran at about 215 in city driving, and at idle, I'd get to about 235. I verified all the temp readings with a non-contact thermometer. The gauge is accurate. Now i miss that REALLY hot heater air.

i thik i will look into a new elec. fan to replace the clutch fan and check the relays and all that jazz

make sure your fan shroud is all there too