Hello all,

I'm typing this from work and thus I'm not able to check out anything on the jeep at this moment. I may have made a severe mistake and am looking for some guidance.

2 Days ago, i did a complete coolant flush on my jeep. 99xj. She was pretty dirty with rusty mud in there, not sure why yet, perhaps its related. Heres the thread on that:
https://www.cherokeeforum.com/f2/blo...4/#post3592158
The jeep was full of water and flush chemical when I left for work yesterday. I wanted to let that circulate until today.

Yesterday when I got home, I noticed she was dripping water from the lower hose, I had not tightened the hose clamp enough. It was too hot to get under there however without being burned so I let her cool off and tightened it again in the morning. In the morning the puddle didn't look too bad , i tightened the clamp as much as I could with a screwdriver and drove to work. I payed attention to the temp gauge the entire time, worried that she might be too low on coolant. The entire ride the temp gauge read 210, occasionally slightly over, but nothing crazy. I noticed I had no heat, which should have been my first clue but I wasn't thinking. My heat was super hot the night before when I flushed her out. So the coolant was definitely low.

During the drive she started behaving strange, holding a high idle, shaking excessively at a stop, and began to develop a loud knock. Again the temp read fine and with my limited experience I did not think she was overheating. The knock began to get concerningly loud and I turned the jeep off at a red light. It barely started when I turned it over again. I made it to work, noticed she was still dripping coolant.

During lunch I went out to investigate. I properly tightened the hose clamp on the lower hose with a socket to stop the leak. Looking under the rad cap I saw it was wet, and there was still plenty of coolant in the reservoir, so I drove around the parking lot. Same strange behavior, but no knock at all at first. In fact she sounded just fine. Within a few minutes the knock came back, significantly louder now. At first the knock was only present while in drive, and would stop when I put it in park or neutral. Now it was very loud, sounded like it was coming from the bottom end, and would continue in park. Temp was still fine.

I parked it and turned it off, and all of a sudden the temp gauge rose all the way into the red. Steam was coming off the engine and seemed to originate around the head gasket. It was only now that I realized what was going on.

So as of now I am afraid I have made a really stupid mistake and destroyed my engine. After work I will fill her back up with water in hopes that nothing is damaged and that I can make it home. Would overheating cause such a serious loud knock from the engine, or have I most likely caused a serious mechanical failure? I cant imagine no damage has been done. I feel really stupid.

My reservoir was still full. However it was full of coolant, and my rad was full of water, and under my rad cap was not green whatsoever. No coolant had at any point been taken from my reservoir. I also do not have the 0331 head.

I quickly checked my oil and it looked totally fine.

Any thoughts? I'm extremely distraught that I may have hurt my engine with such a stupid oversight.

 

How long is your drive to work?
I'd fill the radiator from the rad cap not the expansion bottle, start the engine, see if it will take any more and then put the cap back on and drive half a mile or so (preferably with some elevation changes) and repeat. Once the engine starts warming up, be very careful with the cap.
If you're lucky the knocking might just be boiling in the block. At the other end of the spectrum, it could be toast
But, it should get you home!

 

Did you bleed the system after the flush? Overheating will definitely cause a knock and the whole shabang once the oil overheats and bad things start happening.

 

Well, the good thing is that since you have a 99, you don't have the problem head of the 2000-2001 years.

But from what it sounds like, you may have a problem. The best thing to do would be to fill the system and see what happens. I would not put any more money into the Jeep until you know if the motor is toast.

The good thing is that these engines are pretty tough, and you can easily source a rebuilt engine if need be.

 

Well I filled her up with water and off she went. Finished with another good flush today and ranher for a good while with new coolant. Honestly she sounds almost completely fine. Definitely different, but fine. Damn these things can really take a beating. Oil looks fine too. One strange thing is now when it rev's high and then comes back down, the exhaust makes some small puff/fart sounds. Sounds pretty cool, not sure what to make of that

 

Water pump going bad

 

I'd go ahead and change the oil too.

 

No, he just didn't properly fill the cooling system.

 

X2. This will tell you if there is coolant in the oil better than simply looking at the dipstick. IMO, this is a MUST DO as soon as you can get to it.

 

That's one way to put it 😅

 

What should you look for in the oil if you do this?

 

Coolant. If you can, drain it into a clear container so you can see if there is coolant in the bottom.

 

Also just a good idea to change it after you've overheated, the additives start to break down and you don't want that in your engine.

 

Let it sit overnight, then use a mason jar and drain a pint or so out and put the plug back in. Coolant would have settled to the bottom in that time and that should be the first thing out. Aircraft ground crews check for water in the fuel tanks before every flight by draining a sample from a valve in each tank.

 

Yeah, and if you see a bunch of sliver flecks.....