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Overheating!! Headgasket issue? Maybe not??

scootin

NAXJA Forum User
First stop at this sight - so hello to all. I've been searching around for my topic, which wasn't hard to find in the "overheating" category.

Maybe someone has the insight I'm looking for. Here's my story:

I Just reserected a '92 Cherokee (192K, 4.0, 3" lift, 31's) from a friend that just moved to town. The jeep sat for over a year, and it needs a few things, but nothing major (exhaust, gas tank leaks at seam, leaf springs).

To the point, it was overheating badly, into the red. No "check engine" lights came on. Did the usual inspections, changed the t-stat, flushed the coolant system - nothing helped. Took it to a mechanic friend to do a chemical test to see if HG is blown (hydrocarbons?), and sure enough, the test was positive.

Being capable enough (and no money), I decide to go at it myself. I've now got the head off, and there is no visible signs of HG failure. In fact, it looks pretty darn good for 192K. Now, I'm no expert in this area, but research tells me it should be readily apparent where the HG failed (a swell, or warpage, etc.)

Anyone know how accurate the chemical tests are? It's not that I don't believe my buddy mechanic - he knew he wasn't getting the job anyway, but now I've got my doubts. What other signs show a faulty gasket? A bad radiator wouldn't bring a positive test?

Any other suggestions? Hopefully, I've taken the top of the engine apart for a reason!! If not, at least it's been interesting.
Thanks in advance.
 
This doesn't really answer your question, but a lot overheating on XJs is from the radiators being inadequate. I recently upgraded mine to a two row and I am no longer experiencing overheating problems. Also, with that many miles it very possible that it is not operating efficiently and needs replacing. Is it overheating at low speeds, high speeds, or both? A faulty clutch fan can cause low speed overheating problems. Also, don't over look the obvious. How's the radiator cap? Is there any leakage around the weep hole on the water pump?
 
Sequoia will probably chime in sooner or later... he was dealing with overheating problems for over 3 months... and it turned out that the new radiator he got was plugged with loose solder.... of course that didn't come out till he finally went to get it rodded....
 
It's overheating (or was when the engine wasn't in pieces) at higher speeds, or getting on it a bit. Could let it idle for awhile and not see the jump in heat. Once it was run a bit, she'd climb up and teeter around the red.

No leaks, etc. Rad cap is good and tight. I guess my plan of action is to drop the oil pan, clean her out real good (maybe a kerosene bath), get the new HG on, and run a few oil changes through her. Taking the head to get it milled this week. Might as well since it's off.
 
Everything that you're doing will definitely not hurt anything, although maybe not necessary. XJ's are notorious for their cooling problems and I was extremely frustrated with mine until recently, so I don't want you to go through the same frustrations I have been through. Anyway, I have done a lot of research on this over the past few months and here's what I have discovered. The factory radiators are moderate at best, while functioning at full capacity. With as many miles as you have, its probably clogged and not functioning 100%. Also, from the symptoms you have described it also leads me to believe that it is the radiator. I'm not a mechanic, so take this however you want to, but I just hate to see someone do all that work and not solve the problem.
 
The XJ radiator is marginally adequate when new, but by the time they get to 10 or more years old, they really aren't adequate. I think you should assume that you need a radiator.

Don't plane the head any more than absolutely necessary to make it flat. The '92 doesn't use a knock sensor, so you really don't want to increase the compression ratio if you don't have to.
 
Appreciate the comments. To the point where I'm at, I'm going to clean her out (drop oil pan, clean oil pump, mill head slightly, clean rods, rockers, valves, all new gaskets), get it all back together, and start over with the radiator - assuming it still runs hot.

Any suggestions for a competent radiator? I'd prefer to only do this once (not that it matters, as this jeep is winning the war right now).

Thanks again for the responses...
 
No problem. I would recommend Modine, I just put a modine 2 row in mine and it was any easy install. It bolted right in. :D
 
Overheating

I have had numerous overheating problems. Once it was the reservoir cap. Another time the actual reservior. Then I got a new engine and it overheated right from the beginning. It was tight so it would run hot for awhile , but after 2000k it still did it. Ended up being the clutch fan. There is a way to test it too. If your running hot , say around 210 or more. Shut off the engine and try and turn the fan. If it doesn't turn it is working. If it turns fairly easy it isn't working properly. The fluid inside should get to a certain temp , I'm assuming around 200 degrees and cause the clutch to engage. Changing it isn't any fun , but it is worth it.
 
If the friend/mechanic sampled the coolant with the normal 'block tester' fluid and apparatus and the blue fluid turned green (without sucking any of the actual coolant into the mix) there had to be hydrocarbons present in the coolant. No other way for those to be present unless passed from combustion.

Is possible there is a crack in the block or/and head. Not good news but i carefully ck the head gasket on a job as this for obvious signs. If none are found i then i always have the head pressure tested. As far as the block, look really carefully at each cyl bore for cracks. If there is one present is usually not too hard to find. Also ck the block deck surface for possible cracks there too.

Block and head cracks are not typical in these 4.0s thank goodness, but would suck to reassemble and still have the problem.
 
I just got my 3 row CSF from Dirk and it's awsome!(See other threads). While examining my stock on, i was amazed it lasted this long. Fins in complete rows missing. Big dent in the drivers sided plastic tank. Just awful. For $160 bucks, this all metal radiator is a blessing!
 
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