so basically i took a trip to rausch creek about 2 and a half hours away from where i am in jersey. and after about almost 2 hours we stopped for dinner. and then after another 10-20 minutes on the road i over heated. check gauge went on and temp guage jumped all hte way to the right. coolant was squirting out all over and my pistons were clanking in the cylinders because of the pressure i guess. but after letting it cool down we put more coolant in it and it was fine. checked thermostat and it was fine too. so it functions fine now until i put the ac on then it jumps back all the way up and the check gauge comes on again after about 5 minutes of driving with ac. any suggestions?

 

Sounds like the radiator can't keep up with the AC condenser's added heat.

How's the radiator?

 

that was my guess.
apparently its bad lol

 

They are cheap and easy.

May wanna do your thermostat anyway. Like $7.


If you have the cash and time I'd just replace everything. Water pump is only $32 or so. Then its just hoses after that, maybe fan clutch.

 

i did the thermostat in like February. and yeah might as well lol. fan enables just fine though

 

Do you have an efan and mechanical fan with shroud?

What year XJ?

 

not a clue. 2001 classic