j4mison

Alright. I've been looking around for a good 45minutes on google, pretty much all the posts say its a blown head gasket, but for some reason I don't really think that's it. Just a gut feeling I wanted to check.

I was driving to my girlfriend's house today, going like 55-60, i get off onto the access road, stop at a stop light, once it turns green, i accelerate normally and start to turn, car dies. I put it in park and started it back up, no problems. I pulled into a gas station and let it idle for a second, everything sounded fine, my gauges were all fine, I decided to go slow and limp it the next mile or two to her house.

After maybe a mile, my temp gauge jumped all the way to overheating all of the sudden and stayed there, along with my "check gauges" light coming on. I was surprised because it literally jumped straight to 260 from about 200-210 where it normally runs. I kept going, the light went off and my temp gauge went back to normal (210) i pulled into my girlfriend's driveway, as soon as I slowed down to turn, it died again, and white smoke came out of my hood. Just a little bit. I got out, smelled coolant, and figured I had a coolant leak. I can see some coolant near my radiator cap. kinda under the air box and near power steering pump in that little gap right there.

Now, with the stalling, everyone is saying it's a blown head gasket. Would that mess with my temp gauge like that, or is that just a weird coincidence it happened? I'm not too car savvy, and couldn't find anything on google with that, so i figured I'd ask.

PatHenry

I think you COULD have multiple issues.

First the stalling. While it's possible that you have a blown head gasket, stalling alone is certainly not a direct "symptom->diagnosis" for that.

Second the overheating. Your model XJ ('98) gets the temp information for your gauge from the thermostat housing. Therefore from your description what I would suspect happened is that the thermostat closed up on you, the coolant in the engine heated up but you didn't see it register until it opened up and suddenly - boom - overheating.
The overheating could have ruptured a hose or blown back through the radiator cap (hence the coolant in the area your mentioned).

Now you could very likely have blown the head gasket from the overheating - and you stalled BEFORE the overheating (maybe it was overheating and you didn't know it.. that's also possible).
Did you drive the Jeep with the temp in the red?? I hope you did not, as that's a very very very bad thing to do.

So if I were you, I would NOT DRIVE the Jeep until you have figured out what's going on. I would start with a trip to the Auto parts store and use the loan-a-tool (free with deposit) program to get a coolant pressure test tool and a compression test tool. The first to check that your cooling system holds pressure (and to find any leaks caused by your overheating) and the second to test the engine for a blown head gasket.
The compression test MAY not be determinate - in other words, you could pass the compression test but still have a bad head gasket.
There are test kits that you can buy to detect cross contamination of things (in other words, if your head gasket is blown between oil, coolant or exhaust ports). You might want to grab one of those as well.

If you have good pressure holding in the cooling system, and a good compression test, and your coolant has no oil in it and vice versa and there's no exhaust gasses in either - then you aught to replace your thermostat.

j4mison

That's totally possible... the overheating before it stalled. I was listening to music, I may not have noticed the temp gauge rising...

I replaced the thermostat when I replaced my water pump, maybe 10k miles ago or less. I doubt it could've gone bad that fast. I'll go get a test tool and update the thread later on. It's about to get dark out, and my car isn't home... I don't want to drive it home if it is a blown head gasket for fear or warping or cracking the head.

PatHenry

I had a water pump go out on me (the impeller broke clean off) when I was 500 miles from home and ended up having to replace it on the side of the highway... not a good memory at all dealing with that fiasco. However, it proved that when you start to overheat, it's really quick.

I would definitely test and be sure. Blowing a head gasket is bad, but not the end of the world in the I6 - damaging the engine block or head is definitely worse.

j4mison

So after replacing the head gasket and getting everything back together, on my way home, the "Check Gauges" light comes on and the temp goes from 215 to 260 again.
I turned on the heat full blast, knowing i had to just limp it home, and wanted to try anything. After about 5 seconds, the light goes off, and the temp goes back to 215. I drove like this for about 3 miles, then turned the heat off, again, 5 seconds, temp goes to 260. Turned heat on, 5 seconds later, temp drops back down and the light goes off.
WHAT THE HELL IS HAPPENING TO MY JEEP

5-Speed

Sounds like you still got some air in the system. Typically they bleed the air out by themselves but you have to make sure you have plenty of water in the overflow. Once it heats up, shut it off and let it cool. If there is air in the system, you will hear the reservoir bubble as its cooling.

PatHenry

Definitely get the air out of the system. I usually pop the radiator cap, let it run and keep topping off the radiator with 50/50 coolant until it's full.. once it stops sucking it down (and of course is dribbling coolant) I put the cap back on, make sure the overflow is at the correct level and clean up the huge mess that I just made.

Also, if turning on the heat seems to bring the temp down, it would make sense for you to check out your fan clutch and make sure that it's working and that your aux fan is kicking on. A decent fan clutch is like $40, so if in doubt, I'd replace it. Your aux fan should kick on if you turn on the A/C or Defrost, so I'd check that it's coming on (or disconnect the temp switch on the thermostat housing and it should come on). It also comes on when the temp is in the 218-223 range depending on your year.

s346k

when you replaced the head gasket did you see evidence of coolant in a cylinder?

j4mison

Turning on the heat doesn't bring my temp down necessarily... it more like turns the thermostat on or something. It goes down within a second, from 260 to 210. It isn't like its cooling off, it's like a switch flipped and it dropped temp instantly.

Yes, coolant in 5-6.

Turbo X_J

What were the results of the compression and/or leak down test before and after the head gasket replacement?
How warped is the cylinder head and block and were both checked for cracks?
Have temperatures been verified by IR thermometer?

PatHenry

Turbo's asking some very important questions. Also he mentioned an IR thermometer which is key to determine if your gauge is reading correctly or not.

If your temps are accurate then that like that sounds like air in the system. If it's fully burped and still happens, change the thermostat... I would replace that thermostat anyway since I feel that if there's any doubt, it's cheap and easy enough to replace (or at least check the operation with boiling water).