Hey guys I’m new here. I searched for this topic but I decided to make a post to see if I can get some help troubleshooting this issue.

I have a 2000 WJ Laredo 4.0
140k Miles

So some background, i got this jeep I ran it all winter long. Prev owner told me that he replaced radiator at some point. I suspect he put in a 165 degree thermostat cause that’s what it ran at all winter. Now this summer I’ve noticed that at an idle or slow driving the temperature creeps up to almost 210 then drops back down when I start driving at about 35mph+ I thought it was just the heat but we had some colder nights that it’s been doing it.

i replaced the E-fan relay.
engine seems like it runs fine
radiator bleeder nipple is missing (prev owner plugged the hole) plan on fixing this soon with a new nipple and some Teflon tape
mechanical fan spins freely when engine is hot by hand
mechanical fan spins with some resistance by hand when engine is cold.
Coolant looks relatively new (no signs of oil)
no exhaust smoke

can somebody help troubleshoot this for me? I’d like to at least get it back to acting normal before I blindly dump money on this problem. Could it be the fan clutch?

other than that this car runs great. I just don’t wanna kill this reliable 4.0 trying to get some dinner at a drive thru. Thanks everyone!

 

210 is normal, the 165 is cold for the 4.0. Operating temp should be about 195 on the temp gauge however the readings do tend to be very close to straight up at the 12 o'clock position reading at 210. It sounds like the t-stat is stuck open honestly. If its bothering you fix the bleed nipple and replace the thermostat with a 195. Personally I wouldn't worry about the 210 reading and keep driving it, you may get a check engine light for the low temp if its not heating up fast enough, if that happens its not catastrophic it just won't ever reach closed loop and thus won't be monitoring the O2 sensors, so you'll have a rich condition.

 

my 2000 WJ 4.0L only has an electric fan and it runs at 200-210* all the time, weither it's moving or parked idling, hot or cold weather. Actually, it's a 99 because it was built in August of 99 and sold as a 2000. It's always had a 195* thermostat in it and the only time it has overheated was when it was low on coolant because of a leak. What they are telling you is correct. The engine is supposed to run at 195* in order for the system to go into closed loop mode so the computer will rely on the 02 sensors to control fuel mixture. In open loop mode, it's using preprogrammed data and running rich.