I recently purchased my 1st Jeep. A '95 XJ SE 4.0 w/auto trans. It has 77,000 original miles (CARFAX confirmed). After driving it for a couple of days it ran rather warm and pushe coolant back into the resevoir. I figured with everything being 15 years old that I would conduct a little maintenance and replaced everything to do with the cooling system with exception to the heater core. The radiator is a 2 core aluminum. Anyway, after replacing everything it now runs @ the edge of the reed on temp gauge while driving 55-60. I took it to a local shop today and had system flushed and pressure checked. All checked out OK, but still running very warm. Electric fan works properly and fan clutch is new. Anyone have suggestions? I could really use some advise.

 

Did you happen to replace the temp sensor on the back of the block that sends the gauge the signal of where to run? Its on the back/drivers side of the block. My 96 also runs hot but not that bad and I have everything new minus the gauge itself. I have a 3 core aluminum radiator so I am bummed with it not being cool as well. Other then that you may not have all the air out. Here is what I did to burp out all the air. I put this into the upper coolant hose that runs near the valve cover. Works very well if you hold it up like this and fill it at the same time.

 

could it be your gauge?

 

Never heard of anyone with a bad XJ temp gauge...but its an electrical component so it could have a mind of its own for sure...haha

 

check your cluch fan...i replaced my whole coolant system just to find that it was a bad cluch

 

Thanks for the info. I don't have an in-line flush valve, I'll have to try that to make sure I can get all the air out.

 

Fan clutch is new also. I know the gauge is off some from what the guy that flushed the system told me. I acquired an infra red heat checker today so I can check temp at different places and try to diagnose the problem. Thanks to all for the replies and info. If I get it fixed I will post my findings.

 

If I may make a suggestion, go to the hardware store and piece one together out of brass ( flush kit). I personally have seen the plastic ones fail, plus heard of other being hurt if they fail.

 

Good idea with a brass unit but the plastic one I have is made for cooling systems and much cheaper then brass pieces. The plastic one will not fail if its made for a cooling system. Ive had 2 heater control valves fail on me one exploding and this valve is still just fine.

Clutch fan is new as per question above.

 

I did the exact same thing to get air out of the head

my money is on an air bubble somewhere

 

I have had an XJ with a bad gauge but after owning 3 XJ's and have gone through overheating issues with all but 1, my guess is either an air bubble, or the heater control valve.

 

Thanks for the brass unit idea. That will definitely last longer than plastic. Heater valve is new also. I am planning to work on it tomorrow. Maybe I can finally lay this issue to rest. Will post any findings. Thanks to all!

 

Well, I worked on the problem again this weekend with no luck. Tonight I installed a new Mr. Gasket thermostat, new temp sending unit and flushing tee in heater hose to bleed out all of the air. On the test drive it did great for about the first 5 miles or so and then the temp started to climb. Stopped and opened the cap on the tee a little and let out some air. Topped off with coolant. A friend has been helping me and we have been working on it at his shop. After topping off and letting idle to see if we could get more air out of the system it ran around 210 @ idle. On my way home temp ran around 220-225 by the gauge. Seemed to climb so I swithced the heater on and it stabilized. THe gauge still seems to be off some because the fan comes on @ about 225-230 by the gauge. I am going to drive it some to see if more air will work its way out. I am now wondering if I need to go to a 3 core radiator. Radiator is new but not 3 core. Seems to build heat when under load . Anyone have anymore suggestions? All help is greatly appreciated. I have never had an automotive issue stump me like this.

 

its interesting that you are overheating not at idle but during driving condition. makes me think something else is the problem, but dont ask me what, its a good mystery

 

What is the temp? anything between 190 and 210 is ok.
What grade of thermostat installed?