Would a bad fan clutch cause your engine to over heat? My xj on over heats when driving, usually within 15-20mins, but if she's sitting still for 30 or so minutes (that's as long as I've done it) it wont over heat. This is with a/c on as well.

How about a radiator cap?

 

The fan clutch is just 1 of several cooling system components, any of which can fail, thus causing overheating.

 

Well the water pump, t-stat,t-stat housing are new, and everything has been flushed.. and the head isn't cracked.

Im just wondering if the fan clutch or radiator cap could cause it to over heat while DRIVING in about 15-20 minutes.

 

We've had this happen on another vehicle. The fan clutch wouldn't release, therefore at highway speed it was still engaged instead of freewheeling, blocking some of the airflow. So it got hot on the road but was ok at idle. Definitely worth checking.

 

Ok thanks, is it worth getting the zj fan clutch?

 

Why would u not suspect the radiator as well????

 

Save some pain. and try another T-Stat. I had major issues and swapped Pump, Fan Clutch, T-Stat, Hoses, & Rad. Mine was still capping when I drove her. Took 2 New T-Stats as one was bad from the box.
What's the condition of the Rad?

 

How would I check the radiator?? Im not going to just go buy another one.

 

you can rent a pressure tester from most local part stores..im sure checking that might help..

 

U've only got 2 cooling system components u haven't replaced..... the fan clutch and the rad. The fan clutch is the easiest to replace of the 2. If it stiil overheats, gotta do the rad. That means another drain/refill.

 

over heating while driving leans toward a circulation problem ,over heating when sitting leans toward clutch fan issue

 

Not to distract from the good advice you are getting here, but might a head/gasket do just that?

Fill it to the brim, and with the cap off power-brake it a second, and see if it bubbles (or geysers). Two minute test.

 

Radiator cap hasn't been replaced. It's a $5 part and they wear out. Try it. Fan clutch would cause heating up sitting still, not at speed.

 

Guess what?? Got a whole in my radiator.. gonna rent a pressure tester tomorrow to make 100% sure.

 

A HOLE in the radiator means replacement time. Put a new cap on with it.