I have a 98 XJ that has been having cooling system issues since I bought it. Details...

The radiator had red goopy gunk in it and it would sneeze fluid out of the radiator cap while driving. There were no overheating issues, and the heating was pretty much useless. I changed the thermostat, and radiator (to eliminate the possibility of it being a transmission cooing line leak) flushed the system following the super flush video that's floating around this forum, and filled it back up.

The fluid loss persisted and it looked like more gunk was floating in the radiator, I thought I didn't get everything out of the system so I took it to brakes plus to flush the system and have an engine block test. When I got it back they told me the pressure test and block test came out fine. I found they didn't flush out the reservoir tank. I took it back and they flushed it again on warranty.

There was no change so I decided to do the engine block test myself because I couldn't think of anything else it could be besides a head gasket leak. I drained about .5 gallons from the radiator to get the level low enough to do the test. It came back positive for exhaust in the radiator. I was getting set for a head gasket change, but my buddy suggested I try out Blue Devil engine sealer. Did some research and it looks like it's pretty highly regarded. I figured I'd give it shot since the leak didn't seem too bad.

I headed over to the garage I'm borrowing and on the way. On the the way the temp held at 220, then spiked to the red zone. I immediately pulled over and let it cool down, I headed back to my apartment since it was much closer. On the way the temp stayed at 220.

I went to auto zone and picked up the Blue Devil pour and go sealer. I followed the instructions exactly. While I was letting the jeep run to allow the sealer to circulate the temp was sitting at a consistent 220. The next day I opened the radiator up and topped the fluid off, let the engine warm up again to see if there was any change. When the temp reached about 170 I noticed white smoke coming out from under the hood.

The upper radiator hose had what appeared to be radiator fluid bubbling out out from where it connects to the thermostat housing and it looked like that is where the smoke was coming from. when the car cools down and the air warms up I plan on pulling the t stat and check to make sure it isn't all gunked up, and make sure the hoses are intact and tight.

Has anyone experienced this before and how can I stop it from overheating so I can get to the garage I'm borrowing. When I get there I can flush, test, fix, what ever the may be needed with out freezing my fingers off.

 

The correct thing to do would be to not put a sealer into the system. For future reference stop listening to this "friend". Maybe someone can recommend a flush that is meant to strip the sealer you put in.

The next correct thing to do would be the headgasket. I prefer an MLS. Plenty of videos online on how to do it. It is painfully easy. If you can read and lift 60ish pounds you can do it.

 

X2.... never ever use sealer crap inside any part of your vehicle.... radiator, engine, you name it. It will royally F- up your vehicle.... that stuff is nothing short of pure unadulterated snake oil, that will always do more damage than help. Sorry...but it's true. Kinda like radiator stop leak...sure it will plug up the leak...but they don't tell you that it will plug up things you don't want to as well. Those companies should all be sued out of business.
Hope you can get that crap out of there, so it can be fixed the right way in order for it to give you years more service.

 

I agree the best thing to do would be to tear the engine apart and swap out the gaskets. I was somewhat disinclined to use a stop leak but I figured it was worth a shot since I couldn't get it to a garage and there's also the -10 degree temperatures. I know the stop leak didnt cause the over heating since that started before I put any in there. The only thing I did between professional flush with no over heating and overheating is drive 30 to 50 miles and an engine block test. I'm thinking I'll test the t stat for functionality in a pot of water, perhaps the fluid isn't circulating properly. I have a chemical flush that I was going to use anyway, but I need to get it to the garage first.