I have a 97 TJ 6 cylinder with a 5 speed, aprox 120,000 miles. I noticed when driving yesterday in Florida's spring heat that my temp gauge rose just above 210 on the freeway at 70 mph and with the AC on it went upto 235 range.

Being that the temp was always at 210 during the winter,I would guess my thermostat is ok, to be honest I havent looked to see if the jeep has a viscious clutch on the fan, do they go bad often?.... is it time to try a chemical cleaner, change the thermostat? Do I need to add an electric fan?

Open to ideas, they say it gets warmer here....
Doug

Pretty good info http://www.arrowheadradiator.com/overheating_causes_and_cures.htm

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Great information and good reading, thanks

Since it is getting to 235 with the car moving down the freeway at 70, the probelm isn't then fan. I'd flush the entire cooling system and see if that helps. I bet it is a water flow/level problem.

Or the old thermostat is not opening all the way. I'd go for a new 195* thermostat right away.
Retarded timing can make it run a bit hotter than normal too. Never forget the sender can be taking a nap.
The engine cannot be hurt unless it pukes out it's fluid. Have you checked the radiator level when it is cold? Might have a slow leak.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Thanks for the suggestions, The radiator/overflow tank level is ok. I agree, a good flushing, changing the coolant and thermostat is a good first step.
I bought the jeep 2 years ago, and just got the AC working, so the additional tempature load is new to my summer driving, and I have no service records as to coolant maintenance. The coolant is clean, still green, no sign of rust or lumps,hopefully the radiator isn't too clogged up.

A few years ago I had a motor start to run a little hot, but not to the extent it would boil over. I got to trouble shooting it and checked all the usual items that normally cause this problem and came up with nothing. After the problem became a little worse I decided to remove the water pump and have a look at it; I found all the impellers corroded down to little nubs that would barely move any cooant at all. I had clean coolant and no signs of corrosion in my radiator, just corrosion on the pump impellers. The pump also did not leak or have bad bearings; only way to see it was failing was to remove it.

Jesus John what had you been running in it? Ocean water? I would have been pulling my hair out before I removed the pump! The impellers would have never crossed my mind.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />