mcd58

i ran into a big coolant issue a couple days after getting my jeep. i went off roading and the jeep was doing great until it started to over heat. i stopped and got the engine cooled off and it was running fine. until when i was on my way home when my temp gauge went all the way up. i pulled over right away and once i stopped my coolant started pouring out of my jeep. i have a 00 xj sport with 79k on it. any ideas of what this could be. i have heard possible head gasket, hose popped off, cracked radiator. i have looked for lose hoses but i havent found anything yet. i will be doing a pressure test tomorrow.

tjwalker

You have an 00, which has the 0331 head on it from the factory. This head has a casting defect between cylinders 3-4, which can lead to cracking on the unfortunate ones.

An overheat really increases the chance of cracking this head. A cooling system pressure test is a good idea; take a good look through the oil fill cap......sometimes you can even visually see the crack with a good light when the system is under pressure.

And if you haven't already done so, educate yourself about this nasty habit of the 0331 head. I hope that is not your problem. But it sure could be. Lots of threads on this, so check them out. Good luck and keep us updated!

Nothing-2-Deep-4-Cherokee

where excactly was the coolant pouring out of? and was any type of coolant or anything seeping out of the thermostat housing?

mcd58

i have read into the 0331 issue and i dont think its that. i couldnt tell where the coolant was coming out of because it was everywhere and it was dark out. by the time i got to the front of the jeep it was all gone. i think i have a clogged hose. because when it started over heating coolant was coming out of the bypass valve also water very slowly goes into the radiator cap. it would fill up than take about 30 seconds to go back in. none was coming out of the head gasket or off the sides of engine so i dont think its engine related.

Fsher21

What bypass valve are you talking about? You don't need to be looking at a bad head/gasket as a source of all the spilled coolant, that would be the result of overheating AFTER the coolant loss. You need to be looking for where the coolant came from, it shouldn't be hard to find if the leak was large. Is it still leaking? Also the temp spike going down the road could have been the air bubble that was the result of the leak. If it was big enough it would not be purged out of the system right away and can fool the sensor since the air bubble will be a lot hotter than coolant.

mcd58

The bypass valve on the engine coolant tank. It is not leaking anymore it is holding water in the tank and the radiator. My coolant is bad I was going to flush it before this happens. The temp gauge is working normally again.

tjwalker

When you find and properly resolve the root cause (have you?) keep a very close eye on the coolant reservoir.

It is NOT unusual to crack the head during an overheat. Very common actually.

If you are using coolant, start the diagnosis on a potential cracked head.

PocketsEmpty

One thing that hasn't been mentioned yet -- check your freeze plugs. I had to replace mine, and blew one, and had to replace them again. If one pops out, you will lose ALL your coolant very quickly, straight out of the engine block. Here's why I had to replace mine...



I've done this job 3 times now and can tell you all about it, lol. It's hard to get up in there and see them when it's all together, best you can do is get a little mirror and a flashlight (one with a bending neck on it worked great for me) and scope them out under the exhaust manifold.

Also, you mentioned your coolant was "bad". Was it brown and muddy? How long have you had the jeep? An improperly maintained cooling system will cause these suckers to rust from the inside out, which is exactly what happenened to mine above. Another thing to mention, there are 2 more of these: one on the back of the cylinder head and on the back of the engine block. If you're leaking from those, you'll have to either pull the head or the engine to fix them properly. I've heard it's possible to remove the tranny and get them that way also.

RTorrez1

You need to take a good look at you oil and see if you have any coolant in it. Like Fsher21 and tjwalker said it is very possible that you cracked the head. Just because you don't see coolant coming out around the head out side doesn't mean that the head isn't cracked. The first thing you need to do is stop running the engine until you find where it is leaking from and drain the oil. If you keep running it and you do have a cracked head you will cause a lot more damage to the engine and you may end up having to rebuild it instead of just replacing the head. keep use posted on what you find.

mcd58

my coolant was brown so i was going to do a coolant flush soon. i have owned the jeep for 4 days now. i will stop running it and change the oil before i put it back on the road. ive pulled the dip stick and cap and didnt see anything on there except oil that isnt milky or anything.

mcd58

i had a bad radiator cap and a clog in the radiator. i did a flush and got all the old coolant out but i still have the old in my overflow tank. should i flush this. if so how?

mikesignal

the overflow is only held in by 2 bolts. just unscrew them and take it out

mcd58

i flushed out my overflow tank put a new radiator cap on, pulled the radiator hose to flush the coolant, and filled it. it was running fine for a few days. no overheating no issues. now today while my brother was driving the jeep started overheating again and dumped coolant out of the overflow tank. what is going on with my jeep.

freegdr

Overheating when ?

mikesignal

have you changed the thermostat and water pump?