98 XJ 170+ miles. So, heres the issue I'm having. Normal everyday driving, heat holds up normally (210 or just a hair past). On longer drives, creeps towards the 220 mark then SHOOTS over to the red (260). Pull over, let her rest while the coolant boils in the reservoir. Once it cools, reservoir is full. I get going again, moves back to the 210 mark, bout 20-25 mins, shoots back to 260. This time, hardly anything in the reservoir. Fill it to the half mark, and get going. This time NO ISSUE!! Temp stands stable at 210-215, until the next long drive. Let me mention that I didn't have a thermostat in. The fan works fine when my A/C is on also. So today I changed my hoses, flushed out the system, new thermo and gasket and all new coolant. Thought about changing the fan clutch, but seems good, no free spinning. SO, whats y'all take on it?

 

Your water pump might be shot.

 

Thermostat. My 90 had the same problems and I found out the previous owner didn't have a tstat in. Basicly your water pump is just constantly circulating the warn water and the water doesn't sit in the radiator long enough. But since you did everything else I'd say also do the water pump just to be good.

 

Bruce... how is it that I ALWAYS seem to find you on this huge thing everyone calls the internet? It must not be too big after all.



Mike

As to your question, I would take out your radiator and take a hose and flush the outside of it. Mine was 50% clogged due to the time the two of us went mudding by base in italy. It is the most likely cause and while you are at it, remember to flush the tranny cooler too. If that doesn't solve it, I would suggest replacing your water pump as it may be worn out, sometimes you may not get the symptoms of it being bad, but mine was and so far has cured its over heating issues.

 

X2 your water pump might look like mine did. I replaced it with a Flowkooler water pump from Quadratec.com

Here is what I discovered

 

Mine looked almost identical and I too did a flowkooler. I have since ditched the ac fan and clutch fan and did th Taurus fan upgrade. New rad, new heater core, new tstat and housing, and hoses, now I sit all below 200 with ac on and have never seen over 210 while wheeling slow with ac on, also have good vents. I would say rad is clogged on outside and you need a tstat and I would change water pump. Good luck!

 

Seems funny! Cherokee soul mates!!! I think I got her fixed up. Wifey drove it around with the needle not hitting 210.