I just bought my XJ last month with 130K miles, so as far as I know the fan clutch is original.

I hear ya, I don't want to sweat it too much, but if the right way to fix this is a new fan clutch and going back to 195* t-stat, I'll do it. I just went out and tried spinning the fan...I could easily turn it by hand, but it would not freely spin. It wouldn't even spin a half turn before coming to a stop. That sounds like what you were describing, so it's OK?

 

Yes that's what I am talking about..I just kinda turn mine and feel tension.I don't suggest the 180 t-stats..On bigger motors and mud boggers sure but on our XJ it's just my opinion 195 tstat works best. To me if you have to put in a 180 to prevent over heating you are just putting a band aid on the issue.. Other things to look at is 3 core radiator, high flow tstat housing high flow pumps..When I replaced the motor I put a high flow pump and tstat housing and one of the nice balanced tstats..Do not get cheap tstat.

 

Yeah, I have a new 3 core radiator and new pump (not high flow). Still have stock t-stat housing. What is a balanced t-stat? Never heard of that...I just bought the 180 at AZ for $10-$12.

 

What I have is the "Mr. Gasket Balanced Flow Thermostat" Part# 4365. Also the Stant Superstant is a balanced flow style..Basically all they do is give tighter variances of within 2 degrees as normal ones are more like 1020 degree variances. Just get a better more consistant flow..I think the Mr Gasker one cost me like $10 at napa..

Also if you replace your tstat housing replace the temp sensor/sending unit that plugs into it..

 

OK, I'm back to maybe the fan clutch isn't working...I feel resistance when I turn the fan with the engine cold. Kinda feels like there's jelly in there and it spins less than a full turn. So I thought that when the engine is hot, there should be more resistance, right? I let it get up to about 195, then shut it off and immediately go up and spin the fan...it has even less resistance and almost freewheels spinning several turns by hand.

It could just be that I don't understand completely how these fan clutches work, which I don't.

 

Hummmm, it may be different on the 96....mine is a 89.

On mine I run a constant 210* and that is with 172,000 miles on my Jeep. Even with my old radiator it only ran about 210-215*, still has the original water pump and tstat housing. Heck as poorly maintained as my Jeep was previously it may still have the original tstat.

The fan clutch on mine is reasonably stiff while cold and about the same while hot.

Do you still have the fan shroud intact?

Only Jeep I have seen run unusually cold is my buddy Brian 1987. Without a shroud, new radiator and even a 195* tstat his still only reaches about 170*. We even check it with a mechanical guage.

 

My "coolness" is due to my 180* t-stat and 3 core radiator among other things

Yes, my shroud is intact. I think I'm going to go get some lunch and try to let it sit and heat up past 215* and then check the fan clutch again.

 

So I let it sit and creep up to 215 when the electric fan kicked on, then immediately shut it down. The mechanical fan continued spinning pretty freely for at least 5 seconds. When it came to a stop, I spun it again by hand and it was about the same as when cold...has some resistance and spins less than one turn.

So there's some resistance when cold, same at 215, and less at 195. I'm thoroughly confused. Someone enlighten me...

 

I don't like replacing parts *****-nilly, but I went ahead and picked up a fan clutch from AZ for $36 with lifetime warranty. Just taking it out of the box and spinning it in my hand, I can tell a huge difference. It has more resistance stone cold than my old one has when hot. I'll find out for sure when I install it this weekend hopefully.

 

Do a write up to add to the tech section 96. Take several pictures and document the steps involved. We look forward to you having a cooler Jeep when this is installed.

 

I just might do that!

 

WOOHOO!!!! My 4.0L is so happy with its new fan clutch. I couldn't wait for the weekend and slapped it on last night. What a difference! The old fan clutch had enough resistance to spin the fan somewhat, but this new clutch generates some major wind!

So I sit idling in the same drive-thru and get the same beef n cheddar and it's the same temp outside (yada yada) and it doesn't even approach the 210 mark. Then I went and parked to eat and let it idle for a few more minutes and 195 was as far as it would go. okcjeeper, you were right about the 180 t-stat not being necessary if everything else is in order. Immediately went to AZ and bought a 195 t-stat to get it running back in the optimal temperature range.

I'm going to venture a guess that MANY 4.0L XJs are running around with bad fan clutches causing a lot of the "gets hot at idle" problems. If they fail like mine did, it was probably gradual and it doesn't really let you know that it's bad via a noise or anything. It was spinning with the engine running, so who would have thought it was bad until you figure out exactly how they're supposed to work.

If you're idling for a few minutes at full operating temperature and you turn the engine off with the hood open, immediately watch the fan and if it keeps spinning for several seconds, I'm going to say that the clutch is bad. With my new one, I can hardly turn the key off and run up to watch the fan before it's already stopped as the clutch is fully engaged with the engine and stops immediately. CASE CLOSED.

 

Good to hear 96. Sorry you didn't do the write up for our library but very glad your junk is cool now.

 

Oh, I took plenty of pics and still intend to do a write-up on the R&R procedure...just wanted to finish out the thread What should have been a 30 minute job took over an hour, but I'll save that story for the write-up.

 

Allow me to add my two cents here, First the computer as was stated is not active untill the vehicle reaches 180, the sensors are set to run at 192 from the factory so to run at 180 you stand the chance of running in the limp home or open loop (when the computer gets its info from the PROM only not the actual sensors under the hood) this will get you poor milage and performance. As for the different resistance in the sensor, its called a thermister a sensor that adjusts resistance based on heat and is calibrated with the guage in the vehicle, although this is not always the case. I have my t stat at 192 my electric fan sensor is set at 192 rather than 210 as factory has it. I have also rased the back of my hood 1/2 inch making a poor mans cowl induction all this and mine runs about 195 at all times even up hill at 100+ ambient temp. Cooling the Cherokee is a full time job. As for the fan clutch deal always be sure it works, lack of air flow will kill a cherokee in a heatbeat , I also have my electric on a cheater toggle so i can turn it on prior to the computer if needed. Thanks