[BowtieGuy3]

Ok, as if I don't have enuff to fix on this damn thing, now this happens on the way home from doing the brakes....

I'm driving, notice the heat gets a little cold, I look down, and the temp gauge is a bit over 210. About 2 blocks later, the 'beep' of my Check Gauges light is on and my temp gauge is pegged. I pull over ASAP and I'm blowing steam. I'm boiling over from the puke tank (which was puking) and I can hear/feel it boiling in the radiator. I wait about 10 mins for it to cool off, start it back up and hurry home (5 mins from where I was at).
On my side street, I hear the beep, the idiot light illuminates and the gauge is pegged again, this time it stalls (I was only 5 houses away).

This thing has had cooling issues before, but just reg. crap like the Water Pump at 100K, Rad Cap, and a pin-holed #1 freeze plug. All things that were fixed easily.

For some reason, I'm thinking its a stuck thermo...
Any other ideas/suggestions?

 

[Kyle]

Head gasket is what I am leading towards.

 

[BowtieGuy3]

Last time I had the plugs out they weren't discolored, and the oil is just how it should be... Not milky at all.

 

[Kyle]

It still remains that way?

 

[BowtieGuy3]

This was just the other night, and it's too damn cold for me to be outside dicking with analysis. So far it does remain that way to my knowledge.
I pulled the stick, just dirty oil. Pulled 3/6 plugs, all fine (#'s 1-6 and 4. I know I should have pulled 3 also, but I was getting cold.). All a nice chocolaty color... I'm just wanting to know what would cause it to boil over but not puke all the water out...To me it seems like the therm never opened to allow the coolant to flow to the rad...

 

[Kyle]

Well then I would have to agree with the faulty thermostat idea.

 

[flexyxj]

Stuck thermostat,worn out waterpump,radiator shot/plugged,Radiator full of mud/crap(no airflow through it),fanclutch worn out/shot,cooling system needs flushing,blown headgasket,cracked block.Hmm,that's all I can think of,for now.

 

[Mudderoy]

In my opinion this is the true weak link in the 98 XJ design.

My XJ was 3 years old when it over heated. It was the water pump. Those little POS plastic fins in the OEM water pump!

$950 later (Head was milled) Jeep was fine for a few months then the OEM radiator with the POS PLASTIC end caps started leaking. They couldn't fix the plastic, so I had them install a new all metal 2 core.

I've had a total of 5 water pumps!

About 8 months ago after having a slight over heat problem every 4 months (if I didn't remember to top off the radiator), I said SCREW IT and replaced the 2 core with CFS 3 core radiator. The e-fan rubbed a hole in one of the fins of the radiator and radiatorbarn was nice enough to replace the radiator.

During the summer the temp would go as high as the first line after 210. 225?

I have a high flow 180 degree thermostat, high flow tstat housing. New water pump, new belt, new hoses (all of them!)

Now I can smell antifreeze occasionally after driving it. I look and no drips, I check the level by removing the radiator cap and it's full and a nice color green.

I also replace the fan clutch within the last year.

Before the summer comes to south texas again, I'm installing a nice big fast electric fan where the POS mechinal is now. I'm getting ready to install a winch bumper and a winch so I do want there to be ANY problems with air flow.

The temp stays well below the 210 now unless I sit in traffic. It will go slightly higher than 210, but drop very quickly when I start moving again. So I'm happy with it for now, but like I said summer time comes and the temp is too high for my liking.

You could very well have a head gasket problem. Just get that tester that check for exhaust gases mixed in with your coolant. Look for the bubbles etc...

Of course changing out the tstat would be pretty easy too. Check your coolant color. If it is an ugly muddy color I would flush and flush and flush it

It may take a couple of weeks to get it all flushed out.

Oh, and freeze plugs. I had to all the freeze plugs on the intake/exhaust side replaced, except for the freeze plug that had the water heater plug in it.

Whew, nice rant, I feel better.

Edit: I forgot to mention. I took the 2 core to a radiator shop for repair. It had a leak, they fixed it. I never knew it was leaking!!!! That was what was causing the over heat every 4 months.