Temperature gauge

[Atl XJ]

Is it possible to recalibrate the temperature gauge if its reading off or do you just replace it? I already replaced the rear temp sensor (which I was told is the one the gauge reads off of). Is that correct? It reads about 30 degrees too warm. I replaced every component in the cooling system one at a time before I finally figured out it was the gauge. My mechanic hooked it up to his computer and drove it around to take temp readings from it and the highest it actually hits is 195 when the thermostat opens. Just wanted to throw that in there so I didn't get a bunch of responses about "how do you know its the gauge?"
Thanks

[Wayne Sihler]

Your mech was reading the temp at the thermostat housing and the guage is reading it at the fartherst point from there(rear top of head) why would you believe the reading on the guage is wrong?
The normal running temp is 210* .So unless it,s :puke: coolant don,t worry about it.
Been there ,done that.
Wayne

[Atl XJ]

Well in traffic it gets up to 220-230 degrees and then the thermostat opens and it cools way down very quickly. If I run the a/c it never even hits 210 degrees on the gauge and it has a brand new clutch fan on it. The only time it heats up is in traffic and anywhere else it stays a little to the left of the middle of the gauge.

At first, I thought it was a faulty clutch fan (even though its brand new) or I had it installed backwards. So I was told to check it by putting a dollar bill in front of the grill and if it holds the there its functioning, it held it there, not very well, but it did. I still wonder if its a faulty thermostat although its brand new Mopar 195 degree. My mechanic said its the gauge so I'm assuming he's correct. He's been my parents mechanic for years and he's always been very good. Everything on the cooling system is brand freakin new---everything. The only way to keep it running cool is to run the a/c so the other fan kicks on. I really don't know--I'm stumped :confused: :confused:

[Eagle]

The only way to keep it running cool is to run the a/c so the other fan kicks on. I really don't know--I'm stumped :confused: :confused:

This is a CLUE!

The auxiliary fan should kick in at about 217 degrees even if the a/c is not operating. If it doesn't, something is amiss in the aux fan circuit. Start your trouble-shooting there.

[Atl XJ]

Yeah, I need to check that. I haven't replaced that. It has come on before without the a/c, but rarely.
Thanks

[Atl XJ]

I just thought of something earlier, that could be a culprit. I have never replaced the serpentine belt or checked the tension on it (other than the it feels tight test). Its possible that it could be out of adjustment or stretched. I suppose that could cause the clutch fan to not cool properly. Its a long shot I know.

Here's what I'm planning on doing 1. Change out the temperature sensor on the front of the engine 2. Replace the thermostat--its fairly new and oem, but who knows 3. Change the serpentine belt and adjust to proper tension. Any more ideas? I keep on hearing that its pretty rare for a temperature gauge to be out of calibration.

[Wayne Sihler]

You have a 95,?At that age it may be time for a replacement radiator.A good chemical flush or a machine flush would be a first step before replacement.
Wayne

[Atl XJ]

I thought I mentioned this in this thread, I guess not. I have a brand new Modine two row radiator, new water pump,fan clutch, thermostat, hoses, etc. Everything in the cooling system has been replaced. I also recently had the cooling system flushed professionally just in case there was something blocking the passages in the engine. This has been an ongoing problem since I bought the Jeep last summer. It went away over the winter, and not that its warming up again its coming back.

[logdog]

I have the exact same problem with mine. It overheated so bad last summer I had to replace the motor. When I did that, I changed the cooling system, including hoses, belts, pumps, everything.... I still have the problem. The next step is to bypass the electric fan switch to a manual switch i can operate in the cab. So, if anybody out there knows wich of the two wires leading to the fan is the power.....

[Ron Hyslop]

Make sure the water pump is reverse rotation and the belt is routed correctly.

[logdog]

Huh.. Wuts a wader pump?

[Eagle]

Huh.. Wuts a wader pump?

This is a technical discussion forum on which people try to get their problems solved, and other people try to help them.

If you don't have something useful to contribute, please remain seated and quiet in the peanut gallery. We have other forums, such as Off-Topic, where it's acceptable to clown around.

[tireroastin93XJ]

I have the exact same problem with mine. It overheated so bad last summer I had to replace the motor. When I did that, I changed the cooling system, including hoses, belts, pumps, everything.... I still have the problem. The next step is to bypass the electric fan switch to a manual switch i can operate in the cab. So, if anybody out there knows wich of the two wires leading to the fan is the power.....
Mine ran really warm like that without the a/c on so I put a 160* thermostat in mine and it runs much cooler now.
Mike Harris

[Atl XJ]

I'd do that, but it kills your gas mileage. :mad:

[tireroastin93XJ]

I'd do that, but it kills your gas mileage. :mad:
Is 195* the only thermostat you are supposed to run in it?
Mike

[8Mud]

I´ve had more than a few 4.0 and 4.2's, they all seemed to run hot (above 190 or so), better than cold.
A 160 thermo, can cause problems, the coolant goes into the radiator at a cooler temp. what comes out is cooler still, fooling the computer into running the motor continiously rich or in the start up/warm up mode. Makes for really bad mileage and a stinky Cat.

[tireroastin93XJ]

I´ve had more than a few 4.0 and 4.2's, they all seemed to run hot (above 190 or so), better than cold.
A 160 thermo, can cause problems, the coolant goes into the radiator at a cooler temp. what comes out is cooler still, fooling the computer into running the motor continiously rich or in the start up/warm up mode. Makes for really bad mileage and a stinky Cat.
So what is the recommended thermostat, 180* or 195*?
Mike

[8Mud]

I´ve tried 160 and 180 on various motors, both of my XJ´s (88 and 95) now have the stock OEM thermostat in there. Seems to work out the best.
On occasion, I´ve had to change out a couple of thermostats, before I found one that worked right, but not lately, the newer OEM thermostats seem to have better quality control (fingers crossed).
Most of my cooling problems, turned out to be something other than the thermostat, though I have had them fail, especially on the closed system type XJ´s. The thermostat on the early models was a low profile type thermostat that was pron to failing, can´t really remember if the newer OBD I and later models also have the low profile type.

[tireroastin93XJ]

I´ve tried 160 and 180 on various motors, both of my XJ´s (88 and 95) now have the stock OEM thermostat in there. Seems to work out the best.
On occasion, I´ve had to change out a couple of thermostats, before I found one that worked right, but not lately, the newer OEM thermostats seem to have better quality control (fingers crossed).
Most of my cooling problems, turned out to be something other than the thermostat, though I have had them fail, especially on the closed system type XJ´s. The thermostat on the early models was a low profile type thermostat that was pron to failing, can´t really remember if the newer OBD I and later models also have the low profile type.
So I guess the OEM thermostat is 195*? Mine is a 93.
Mike

[8Mud]

Related, but not really a problem solver. I bought a good digital muli meter ($30) with a thermometer lead and sensor. A tube of conductive paste (looks like copper grease), clean the block to metal in various places, the same with the in and out side of the radiator and also a few bolts and studs. Took some temperature readings at various places on the motor, was enlightening. The temp. gauge tells you whats going on at a specific place, which isn´t the hottest or coldest place on the motor, which varies widely.

[8Mud]

I´ve seen different temp. stampings on the flange of various thermostats, most were 195, some said 193. I´d check the book, the OEM Chrysler seems to work best. But then again, I´ve checked thermostats, with an electronic thermometer, it´s often 195 plus or minus 7-8 degrees. I´ve rarley found one that opens at exactly (or plus or minus a degree or two) of advertised specs.

[tireroastin93XJ]

I´ve seen different temp. stampings on the flange of various thermostats, most were 195, some said 193. I´d check the book, the OEM Chrysler seems to work best. But then again, I´ve checked thermostats, with an electronic thermometer, it´s often 195 plus or minus 7-8 degrees. I´ve rarley found one that opens at exactly (or plus or minus a degree or two) of advertised specs.
I guess Monday I'll go to my Jeep dealer and get a thermostat, don't want to screw anything up. Then I'll start upgrading the cooling system. Why doesn't the aux fan switch kick in until the a/c is on? Shouldn't it start the aux fan regardless? Where is the aux fan switch located? Are there replacement ones that make it come on sooner? If not, guess I'm going to go to Auto Zone for their kit. Thanks for all the help! Sorry, I didn't mean to hijack the thread.
Mike

[Atl XJ]

I've done a little research on this and according to what I had come up with, the OEM 195 degree is the best to run for optimum efficiency out of your 4.0L. If your cooling system is operating efficently (which mine apparently isn't) the 195 degree thermostat is more than adequate too keep your 4.0 cool. They do run a little warmer than your average engine, but I'd be exstatic if mine would stay at or below 210 degrees.

[Atl XJ]

Why doesn't the aux fan switch kick in until the a/c is on? Shouldn't it start the aux fan regardless?

It should come on at 217 degrees regardless of if the ac is on or not---like Eagle stated previously. :D

[Atl XJ]

I just wanted to post an update here. It looks like the problem lied in my thermostat all along. It was only six months old, but I had some previous overheating problems and I guess the thermostat got damaged. It barely rises above 210 in traffic now (and only for a minute before it cools down to 200 or so) without the a/c on. With the a/c on it runs cooler. I also changed out the radiator cap with an oem model for good measure. I hope it still cools well when it gets hot outside. Thanks everyone for your help. :party:

The only thing I want to do now is rig up some sort of override switch for the electric fan so I can switch it on manually. :greensmok

[Eagle]

Is 195* the only thermostat you are supposed to run in it?
Mike

Yes