I purchased my first xj two months ago. it ran about 210-220. two days after I got it the cel came on. P0171 turned out the manifold was cracked and head gasket blown. so I said **** then replaced manifold with new pipes and all gaskets down to the head. flushed everything out twice and now it runs about 170-180, maybe 200 if I'm pullin up a big hill then cools back down to 170 downhill. I'm guessing the thermostat in there is a 165 I didn't check it, and the radiator is an aftermarket aluminum somethin or other. what I'm wondering is what temps does your Cherokee run at? I picked up a new 185 thermo but haven't thrown that in being that its summer. if the jeep 4.0s normal operating temperature is around 210 then maybe id be better off putting a 195 thermo in???

 

The correct t-stat is 195. What year is your Cherokee?
Normal temp is give or take 210.

 

its a 96. is there any harm using a lower thermostat?

 

It can effect gas mileage. I would imagine there are other things as well.

 

Mine runs about like that ~165 except when the electric fan doesn't come on really hot days, but I seem to have that connection fixed.

Gets 22 mpg on the rare occasion I get it out on the highway. Haven't checked it yet with the 235/75 tires whether it will get better or worse mpg. Probably worse because the odometer will read low.

I'm sure not going to mess with it NOT overheating. I'm coming to the conclusion Jeeps always have a certain number of problems. If you fix one another one will crop up. So don't fix small problems because a bigger one might take it's place

 

On the speedo issue, I'm running 235/75s and I checked my speed with my local police stationary radar and my speedo reads 2 mph faster than their radar says I'm going and that difference seems to stay constant up to 55 mph. I have yet to time it for a marked mile and a stopwatch which I used to do all the time with my other vehicles. The mileposts on a highway are pretty damn close. NY marks them in tenths.

 

Mine runs to about the first tick mark on the gauge unless im driving for about an hour in a hot day then slowly moves to 210 but doesn't quite get there.

 

If you use the factory thermostat, your temps will be stable. 8983501426AD