This is on my 1996 Jeep Cherokee 4.0L 4x4. My grandfather bought it in 2007 and I bought it from him in 2016, so I know all the work it's had done. This is in Phoenix where we have extreme heat, I've been battling it running hot for quite some time. Below I'll list what I've done, most of it last summer.

-New radiator, had a newish one from O'Reilly's now just a regular one from Parts Authority. My brother has the same radiator in his XJ and it's fine.
-New radiator hoses
-New fan clutch, the heavy duty one everyone always talks about on here, bought it from Napa
-New fan shroud
-Tried a new OEM thermostat from the dealer and a 195 degree high flow, now a 180 degree high flow. Might have helped a little bit.
-Flushed cooling system with Prestone flush and distilled water countless times, got it nice and clean. Using 50/50 distilled water and green antifreeze.
-New Magnaflow high flow catalytic converter
-New OEM oxygen sensors
-New belt
-New coolant temperature sensor
-Water pump replaced about 3 years ago

The electric fan is working perfect.
The lower radiator hose is not collapsing
The heater blows hot
The A/C blows cold, but compressor is slightly noisy.

My Jeep is stock height.
On the highway in the super heat, it's usually 215 degrees.
When out on the trail, it often gets to 230 degrees.
Traffic and sitting at lights sometimes gets to 230 degrees.
This weekend I pulled my 4x8 utility trailer on the freeway and was 220-222 degrees.
A/C seems to make it run a bit hotter.

I'm reading the temperature with a scan tool. I also have an aftermarket auxiliary gauge installed on the dash that's hooked up to a sensor on the back of the head, it reads about 5 degrees warmer, my temps listed are the coolant temp sensor readings at the thermostat housing.

Thanks for any help.

 

I should also add that I've done a headgasket leakdown test, no problems there. It also doesn't use any coolant.

And the radiator cap is new, got it from the dealer too because the O'Reillys one was so cheaply made it was like it was made from melted down aluminum cans

 

There comes a point in our very extreme environment were they on the edge all the time and will run hot no matter what you do. Every tiny thing can push it over that edge. About the only thing I can see that might help a bit is adding a very good remote trans cooler and reduce that heat source in the radiator. The trans might be that straw and just enough.

 

Test the new radiator cap.

 

Have you flushed the cooling system?


I have had to do 3 flushes over the last 4 years to get all the crap out of there.



Also, how old is the auxiliary fan and how do you know it is working properly? Does it come one when it is supposed to, at 218F? I had to run a bypass switch to manually control mine because it wasn't kicking in time for long enough times. Now I am cool most of the time.


Also, what RPM do you idle at?

 

Just for fun. While the engine is hot turn it off disconnect the E-fan and measure the resistance on it also measure it when the engine has been cold soaked.

 

Have you checked the A/C condenser to see if the fins are clean and that the fins are not plugged ? If the A/C condenser is plugged your radiator will not get enough air and you will run hot .

 

It actually has a small factory tranny cooler

How could I test it? I've had 3 different ones in the past year or two

Yeah I flushed it a bunch last summer

Electric fan comes on at higher temps and with A/C, blows nice and hard. I've also got a bypass switch for when I'm on the trails to make it run nonstop.

I've hosed it out last year, looks pretty clean, I can see through it a bit

 

How old is the radiator and how clean is the coolant , because all you need is small number of radiator tubes to plug up and you will start having heat problems when it gets hot out .

 

Agree with you %100, once it gets above 90 the cooling system is under a lot of stress. In stop and go mine is above 210 with the clutch fan pretty much engaged all the time, once the e-fan comes on the temp drops down. The xj cooling system is subpar imo, it shouldn't be struggling that much just in city traffic every other vehicle I've driven has zero issues keeping themselves cool. I'm curious what temps people off roading are running at since they're running the engine and transmission hard going slow.

 

OP, so when your XJ overheats, is the AC running?

Because that happens to mine when I am in 90+ degree weather, in the sun, in stop and go traffic, my Jeep begins to overheat if I have the AC on. No way around it, except maybe finding a bigger auxiliary fan.

The reason I was asking how well the cooling system has been flushed, is because my Jeep had stop-leak used in the radiator years ago, and I am still getting stop-leak residue coming out of the coolant, even after like 4 flushes over the past 3 years. I think most of it is out, and the Jeep does run cooler now that I have gotten most of it, but that product just stays in the system for a long time as it gradually dislodges from wherever it was stuck on and may be clogging the radiator.

 

Key word here is small.
I used to have similar problems to you and lived with it.
Finally I put on a $30 AUX Trans Cooler from Auto Zone, x2.5 the factory size and the temps went straight down.
I used the old factory trans cooler as a power steering cooler

 

I agree, adding an aux trans cooler can help lower the coolant temperature if done properly. The factory set-up is good because it helps heat the fluid up faster when it is very cold outside, but adding a Thermal Bypass is cheap and the proper way to prevent overcooling in cold temps.
I would add the aux cooler before the fluid enters the factory radiator, it will pull some additional heat out of the trans fluid and remove some thermal mass from the radiator.
Now that I think about it, trans fluid isn't supposed to run over 200*F (same for Power Steering), so wouldn't the coolant being at 212*F or higher be a bad idea? Never was a fan of that set-up.

I think it is worth trying a coil cleaner on the HVAC Condenser coils, I am always shocked at how much dirt comes out when I clean them. Could also just use degreaser

EDIT:
But on the highway you shouldn't have any problems. I have 35" tires and towed one of those 6x10 U-Haul trailers from Denver to Tampa last summer. Temps were above 90*F the whole ride, I did 80 mph with the AC on the whole way and temps never jumped from 212*F.

I know the water pump was replaced a few years ago but I wonder if it could just not be flowing enough coolant. I might be inclined to change it with a decent but cheap replacement pump just to see what happens

 

I live and use my jeep in the hottest place in the U.S. other than death valley at it's best during the summer. And I realized right away this was causing most of my issues. I had to get that heat source out of the radiator.

 

I stand by my request even if just for the rule out factor. Add on to that check that the mechanical fan stops abruptly on a hot shutdown.