Overheating Issues

[XJ Wheeler]

Alright, this is gonna get a little complicated but i don't want to leave anything out and need you guys help.

So Saturday i was installing some LEDs so i had the instrument cluster out and parts of the dash off. Since i had the cluster out I put some dielectric grease on the gauge screws and cluster electrical connections. I've heard before it was a good idea on these electric clusters. Drove it that night with no overheating unless i missed it.

Sunday, i replaced the power steering pressure hose and bled the system (first time doing that). Started it, let it warm up, and took it for a test drive around the block. Once i got back home i noticed the temp was about 220 degrees. Then the auxiliary fan cut on but didn't help, it kept climbing another 5 degrees before i shut it off (not wanting it to go further).

Monday, I was concerned so i cranked it up and let it set running for about 25? minutes. Revved it a little to see if it would make a difference. The whole time once it warmed up it ran at about 180 degrees (typically for it in the cooler months). Shut it off hoping for the best.

Tuesday, had to run some errands so i thought i'd test it again so i took the xj. Started it and let it warm up to 180. Went to the store about a mile away and shut it off. Came back out and then went to see my grandma 1/4 mile away, shut it off. Then went to get something to eat about 1 mile away and shut it off. This whole time it did fine. Then i left there and headed home approx. 1.5 miles. Pulled in my yard and noticed it was up to 230 degrees. Got it parked and by then it was up another 5 degrees. But this time the auxiliary fan wasn't on. Also my hood is usually hot when it gets up to 210 but was barely warm.


Ok, up to speed. Now what i'm thinking is i screwed something up with the gauge. Its the only logical explanation i can come up with. Its a '92 xj laredo, 4.0l, AW4, 4x4, with the full gauge cluster. It normally doesn't overheat, 180 at motion 210 sitting in the summer with spiking to 220 when the auxiliary fan would come on and cool it back down. Repairs- stock replacement radiator, 180 t-stat, t-stat housing, rad hoses, and coolant about four years ago.

Really appreciate any help, i very much so don't like over heating problems.

[XJ Wheeler]

What would be the proper way to find out if the engine is actually running that hot? You know, if it is the gauge.

[Mudderoy]

What would be the proper way to find out if the engine is actually running that hot? You know, if it is the gauge.

I can smell it when mine is over heating. Also I would check to see if the radiator is full, you know after it cools down. Is the over flow bottle at the proper level hot and cold. Does the upper hose feel like there is coolant in it when it is over heating? Watch your fingers!

I also have a IR temp gun, so I can scan the outside of the engine, etc...

Other than that installing a mechanical gauge is the only way I know that you can know for sure.

[Carves]

230* on the gauge, Aux fan not activating, Hood not hot .....

..... Im thinking a gauge / connector issue.


First thing - is to confirm the temps tho ... One of those I.R. temp guns are good for checking temps ... not always 100% accurate ... but handy for verifying stuff.

If you have one ... even a multimeter with a thermal probe would do.

If your wallet can handle it ... something like this is a handy bit of kit as a test tool ... and you dont need to be stopped with the hood up - to use it.

---> http://www.xjtalk.com/showthread.php?t=8703

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[XJ Wheeler]

I can smell it when mine is over heating. Also I would check to see if the radiator is full, you know after it cools down. Is the over flow bottle at the proper level hot and cold. Does the upper hose feel like there is coolant in it when it is over heating? Watch your fingers!

I also have a IR temp gun, so I can scan the outside of the engine, etc...

Other than that installing a mechanical gauge is the only way I know that you can know for sure.

Didn't smell anything new, radiator is full, overflow always stays at the cold level, when running upper hose is hot and firm (didn't check it while overheating).

I also have a IR temp gun, where should i check with it? And how do i install a mechanical gauge? Can i still run a factory gauge in combination with the mechanical?

Sorry for all the questions, just trying to cover all the bases.

[Mudderoy]

Didn't smell anything new, radiator is full, overflow always stays at the cold level, when running upper hose is hot and firm (didn't check it while overheating).

I also have a IR temp gun, where should i check with it? And how do i install a mechanical gauge? Can i still run a factory gauge in combination with the mechanical?

Sorry for all the questions, just trying to cover all the bases.

I've never had anything but a 98 and a 99. They are really the same, so the only temp sensor is on the thermostat housing. I think your 1992 has two, one on the thermo and one on the back of the block. I think it uses both of them too.

I would scan the block near the water jackets. Of course the best time to do it is when the gauge is working correctly.

You might just want to change (maybe there's a test) both of the temp sensors.

[XJ Wheeler]

230* on the gauge, Aux fan not activating, Hood not hot .....

..... Im thinking a gauge / connector issue.


First thing - is to confirm the temps tho ... One of those I.R. temp guns are good for checking temps ... not always 100% accurate ... but handy for verifying stuff.

If you have one ... even a multimeter with a thermal probe would do.

If your wallet can handle it ... something like this is a handy bit of kit as a test tool ... and you dont need to be stopped with the hood up - to use it.

---> http://www.xjtalk.com/showthread.php?t=8703

.
So that is basically a digital temp gauge that i can mount up to the dash? Is it that i just mount that lead to a bolt on the engine? How much is the variance on yours (how accurate)?

[XJ Wheeler]

I've never had anything but a 98 and a 99. They are really the same, so the only temp sensor is on the thermostat housing. I think your 1992 has two, one on the thermo and one on the back of the block. I think it uses both of them too.

I would scan the block near the water jackets. Of course the best time to do it is when the gauge is working correctly.

You might just want to change (maybe there's a test) both of the temp sensors.

Yeah there's one on the t-stat housing for the fan and one on the back of the head for the gauge.

[bigjim350]

You could just buy a cheap mech gauge for $10 . Install it where the factory sensor is and get a good reading of what's going on. And if all is well u can just mount that guage or reinstall your factory one a figure out what its problem is. Personally I prefer mech gauges anyway.

Sent from my VM670

[Carves]

Your 92 has the two senders ... one for the gauge and one for the fan ??

Grab your IR gun,
Start the XJ,
Wait till the t'stat has opened,
"shoot" the block temp in the vicinity of the gauge sender as Mudderoy mentioned,
"shoot" the t'stat housing temp after its had a coupla minutes for coolant heat to transfer through the housing.
... and compare your results.

Dont think those things work too well on plastic or rubber tho ... ??


The digital setups are quite good ... My XJ is an update so Ive got a scangauge which displays what the factory temp sensor is seeing ... and the TM2 has only has a coupla degrees variance, once everything is up to its operating temp.

Difference being that the digitals probes are bolted to a housing ... so theres a slight time delay, sometimes, while the housing heats up .... compared to a sensor dangling in the fluid.

The only real issue/odd readings I can imagine using the externallly mounted probes ... would probably be checking how hot the diffs get ... whilst driving around in 3' of snow ... :D

[XJ Wheeler]

If i get some time tonight i'm gonna check it with the temp gun. I think i'l look into a secondary gauge as i am really starting to question all the gauges. Ever since i put in my optima battery years ago my volt gauge always read low (like 11 volts) and after installing my gauge covers it is high (about 16 volts). Plus my speedometer works about half the time.

[Mudderoy]

Oh and I'll add every time mine has acted like this, with the exception of the electric fan not coming on, it was low on coolant.

I think you have a good case for a gauge or temp sensor issue though.

[4.3LXJ]

Question. Do I understand you correctly that you put dielectric grease on the plug in the back of the cluster?

[XJ Wheeler]

Question. Do I understand you correctly that you put dielectric grease on the plug in the back of the cluster?

Yes, and the screws holding the gauges in the cluster since that how they get their power and info.

[XJ Wheeler]

Didn't have time yesterday, maybe today, but to early to tell.

[4.3LXJ]

Yes, and the screws holding the gauges in the cluster since that how they get their power and info.

I am going to make a suggestion here. I think that one thing that is happening with your temp gauge is that you have power bleeding through another contact at that plug. The contacts are close and if the plug isn't in just right or the printed circuit is shifted a little those things can happen. You might need to clean that area up well and use it dry.

[XJ Wheeler]

I am going to make a suggestion here. I think that one thing that is happening with your temp gauge is that you have power bleeding through another contact at that plug. The contacts are close and if the plug isn't in just right or the printed circuit is shifted a little those things can happen. You might need to clean that area up well and use it dry.

I agree. Is there a cleaner made for cleaning electrical connections?

[4.3LXJ]

I agree. Is there a cleaner made for cleaning electrical connections?

I think you might be able to get something at the parts store. I vaguely remember something like that. But do a test first. That plastic may not like it.

[OrangeXJ]

Go to Raido Shack they should have circut board cleaner

[XJ Wheeler]

Ok i finally had a little time yesterday so i could drive it. Turns out it is actually overheating, quite coincidental since i just messed with the gauge. I used an IR temp gun and checked by the temp gauge sending unit and aux fan sending unit.

First i cranked it and let it warn up to 180° and it sat there like that fine. I checked it with the temp gun and it was right on par. Then i started driving it around the yard slowly and it started to rise slowly. It finally got to 220° when i checked it again with the temp gun. This time i got right around 210-220 in the areas of the sending units. This time the auxiliary fan did cut on and the temp came back down to just below 210 when it shut off answer the temp climbed back up to 220 and i let this cycle continue 2 or 3 more times to make sure the auxiliary fan could keep it under control this time. All this time it was sitting so i could watch it with the temp gun, then i shut it off.

Later i took it to get some food to further test it. I cranked it up let it warm up a little (not all the way to 180) and the restaurant was about two miles away. Did fine at 180. Got my order and headed home . Did fine till i got back in the yard to park it and it slowly began to rise. I shut it off before it got to 210.

So it seems like it does fine idling just after starting and while at speed. But once i go slowly and also sitting after driving it seems to climb. One thing i want to note is that it does fine sitting before driving but overheats while sitting after driving.

Also the day this started i had just changed out the power steering pressure hose and had to move and press on the lower radiator hose to get to it. Could there be something with either of those.

[4.3LXJ]

Try checking the mechanical fan clutch. It sounds like the radiator is fine, the efan is fine too. But that mechanical fan sounds like it is not doing the job it should.

[XJ Wheeler]

Try checking the mechanical fan clutch. It sounds like the radiator is fine, the efan is fine too. But that mechanical fan sounds like it is not doing the job it should.

That's what my brother was saying too. How do i properly check it?

[4.3LXJ]

Give it a spin when off and cold. It should not spin freely, nor be stiff. It should turn with resistance. This is a common problem. The viscous coupling wears out over time. A popular upgrade is the ZJ fan clutch which will pass more air, or you can convert to a solid spacer. Are your shrouds intact?

[XJ Wheeler]

I'll check it when i get home and do some research on the zj unit.

The top of the fan shroud was cut off just below the radiator so i had made this one.
http://i1108.photobucket.com/albums/h401/xj-wheeler/2011-06-03182955.jpg

[4.3LXJ]

Nice job. A step in the right direction

[XJ Wheeler]

Bought a fan clutch today so when i get some time that'll go on. Hope it helps.

[bluedragon436]

Did you end up picking up the ZJ unit, or just another stock XJ clutch?? I just got a call that my ZJ Heavy Duty clutch was in, will be picking it up on my way home tomorrow from work, and will put it in on my next days off.. I need to work on doing something as far as a fan shroud too, as mine got gone thanks to the shop that did my water pump..

[XJ Wheeler]

Did you end up picking up the ZJ unit, or just another stock XJ clutch?? I just got a call that my ZJ Heavy Duty clutch was in, will be picking it up on my way home tomorrow from work, and will put it in on my next days off.. I need to work on doing something as far as a fan shroud too, as mine got gone thanks to the shop that did my water pump..

Because of time constraints i just got a stock xj unit, plus i plan on one day going with electric fans. Let me know if the zj one makes a difference in case i change my mind.

Did they lose the shroud or break it? Either way they should replace it. I tried finding one, new or "new to me", but couldn't find one. Although i didn't try online.

[bluedragon436]

Nah, it had been broken before, but I did an awesome job of re attaching it, and apparently they broke that again... and decided not to let me know.. otherwise I would of gotten the part from them and reattached it.. But I'm going to try and hit up the local JY and hopefully they still have some 97+ XJ's that have a good shroud I can pick up.. cause that is the only thing that has changed since last summer other than a few added miles, and this year it is overheating every now and again.. So going to swap in an upgraded fan clutch anyways, and check the JY for the shroud..

[XJ Wheeler]

Nah, it had been broken before, but I did an awesome job of re attaching it, and apparently they broke that again... and decided not to let me know.. otherwise I would of gotten the part from them and reattached it.. But I'm going to try and hit up the local JY and hopefully they still have some 97+ XJ's that have a good shroud I can pick up.. cause that is the only thing that has changed since last summer other than a few added miles, and this year it is overheating every now and again.. So going to swap in an upgraded fan clutch anyways, and check the JY for the shroud..

Shops, can't trust em. That was still your property, at least that's how i think of it. I don't use many shops anymore but when i do i always ask for my old parts back.

[XJ Wheeler]

Well, i replaced the fan clutch. First time driving after i was going down the highway at 65 and looked down. The temp was 250so i pulled it off and shut it down. When it was cooling, the upper radiator hose collapsed for a little but after maybe 20 minutes returned to normal. The overflow filled up as well but didn't spill over. Once it cooled enough i headed back and turned on the heat. It did good at speed but once i hit the lights and stop signs it began to climb again. Shut it down again and while i was letting it cool i hotwired the auxiliary fan and it did great from there all the way home.

Later that day i got and replaced the radiator cap cause of that hose collapsing. Drove it later to get food and it still got the temp higher. This time i wasn't going over 30 and the temp slowly rose till it got to 220 and the auxiliary fan cuts on (i had plugged it back in) and it very slowly started to cool and got back low enough to where the fan shut off. Was home then.

So what would cause the hose to collapse? I have always heard of the lower hose collapsing if there's no spring or the spring is damaged, but never the upper.

http://i1108.photobucket.com/albums/h401/xj-wheeler/2012-04-07110547.jpg

[bigjim350]

My upper hose use to collapse. I replaced with a new hose, and took out the tstat at same time. Never had a cooling problem after that. Not saying you should dirve a DD without a tstat ( I would though). But if you do ditch the tstat make sure you put a washer or something in there to restrict water flow.