i have a 1999 xj 4.0 4x4 wen i bought it it had a 195 t stat warmed up quick and was good i changed it to a 180 and it ran well then as winter rolled around i switched back to a 195. the problem is i bled the system but the truck doesnt want to warm up fast at all. i mean its 30 degrees and i can drive for 40 miles and it still wont reach 210. i replaced it with another 195 and still running very cold. im really stumped on why once i did a 180 it doesnt want to warm up correctly any more i flushed the whole system twice already too. any suggestions.

 

Sending unit for gauge might be faulty or gauge itself might not be registering properly. Try hooking up an aftermarket gauge to confirm. Mine doesn't run at 210. It usually runs at 190-195 on the gauge, which is fine.

 

My 96 4.0 runs at 190-195 as long as i'm going over 25mph. If I'm crawlin or idle for more than 5 minutes it will go up to 210ish. I have whatever radiator came with it, it looks aged and well seasoned. My fan only kicks on when I'm crawlin or stuck in traffic (or a hole)...

You should move to Moab, that will offset the cold-running nature of your jeep. Your jeep wants you to move to Moab - go figure.

 

Thanks for the reply its just wierd that I can drive for so long and the truck not want to warm up to operating temp. Is it possible the ecu or pcm is stuck on warm up mode by any chance and wen I use the heat it gets hot around 2 lines above 100 and the lower heater hose is warm and has pressure and the upper hose has no pressure