So basically when at idle or super low speeds the temp goes to about 220, then cools down, but it takes a long time, and it’s not hot where I am right now, probably 70 degrees, I want to go to Moab next year, and I want to make sure I don’t have any issues. It’s a 92 with 107k.

 

Do I need a new fan clutch, cause at speeds 15 and higher I don’t have issues, the only thing that makes sense to me is that I’m not getting enough airflow through the rad at low speeds. I am just worried because I hear of people that their XJ’s don’t go above 200 no matter what.

 

Could be you're fan clutch going out. I'm gonna leave this one to 00t444e to Diagnose.

First off though let me give you a list.
We need photos of everything
What has recently been replaced or what hasn't been touched
Are you mechanically inclined?
Does your AC fan turn on
Are you ever having to top off the coolant reservoir.

Lastly if you are mechanically inclined this is 100 and 1 posts about jeeps overheating on this forum so all you need to do is look at a few and you'll easily find a list of what you need to check to verify your cooling system is in tip top shape.

 

Well this is was the method I used to determine if my fan clutch is bad.


Funny thing was in my '00 despite it spinning for awhile after turning off the engine
when hot I never had any cooling issues. But I replaced it anyway.
Some guys go for the ZJ clutch fan upgrade but I went stock.
A Napa one which I believe to be a rebranded Hayden.

 

How long has it been since any maintenance has been done to the cooling system? The regular green antifreeze is only good for 4-5 years max then the corrosion inhibitors start to breakdown and you can get rust and gunk blocking your radiator and cooling passages. I usually drain and refill with new antifreeze every 3 years, but if that hasn't been done regularly then flushing the cooling system is a good idea. A bad fan clutch can certainly cause the issues you are having, and they are easy to replace, so you could try that to start with.

 

i just did a flush to see if that would fix the issue, it didn’t, I’m gonna check my fan clutch like that video said and I’ll let you know

 

I just checked the fan clutch, seems fine, but I looked in to the overflow tank and it was empty, it was full when I did the flush, maybe I just didn’t fill it up with enough coolant when I did the flush, I will let you know if my problems go away, my guess is that they will.

 

I had the same problem on the AMC Eagle I had before the XJ and it was the fan clutch at fault. It was even worse because the Eagle's 258 six (direct ancestor of the 4.0) didn't have an electric fan to provide at least some airflow.

 

I am also using the yellow Napa universal coolant, could that make a difference in temps?

 

You used the NAF EXT1 stuff?
Probably not but I use their green stuff.
NAF 1GAL.
Possible that there could be air still in the system.
I swap out mine every other year.
Drop the lower radiator hose. About 2 gallons comes out.
I used to fill up the radiator as much as I could with the Jeep off.
Fill the overflow tank to the full line. Start the Jeep.
Keep adding until it starts overflowing out. Cap off the radiator.
Then drive the Jeep.
After every drive when it cools down check the level and add some.
After a few days all the air will burp out and I get it to the levels I want.
Now I use this:


Attach the funnel and fill up the radiator as much as you can. Put some in the overflow tank.
Start the Jeep.
Keep the idle at about 1500 RPM. Make sure there is always some anti-freeze in the funnel.
After about 1/2 hour usually good to go. Shut the Jeep off and let it cool down.
Check the levels and usually you just have to top off the overflow tank to the level you want it.

 

That sounds ok to me..in summer, all my XJ oscillate between 212 to 221F at extended idle...the factory electric fan does not even turn on till 221F !

So long as the electric fan will cycle on and off (with aircon turned off)..your XJ is normal (imo)

its hot here, when the external air temp is below 70F, the XJ runs cooler

 

I'm not sure about you guys but that would be a terrible product name/code in the UK. NAF. If something is naff, it's not very good.

 

That is just the part number Napa uses for their green anti-freeze.
NAF is what we call the line code. I always assumed it stood for Napa Anti-Freeze.

 

My cooling issues have stopped, it was just low on coolant after the flush, thanks for all your help!