I've been having trouble with a coolant leak on my 2000 jeep xj for some time now. The radiator WAS visibly leaking but I replaced it with a new one. It's still losing coolant at a fast rate (about a gallon every 100-200 miles). It seems like it doesn't leak when parked. I've replaced the water pump, thermostat, and radiator cap. There is no visible coolant anywhere or any noticeable smell of coolant, yet it's still disappearing. All of the other fluids are clean with no contamination. There doesn't seem to be an excessive amount of water vapor in the exhaust, or any smoke. I've taken it to mechanics and they are just as stumped as I am.
Thanks for reading

 

So the mechanics have pressurized the systems?

 

Yes, they performed a diagnostic and said the water pump was leaking, came back, they said the thermostat gasket was it. Each time it didn't effect the rate of leakage

 

That's A LOT of coolant loss. Your year XJ has the head that is known for cracking or have you already dealt with that?

 

I've already looked into that a little. There's no coolant in the oil or exhaust

 

Check this link out.


https://www.cherokeeforum.com/f2/00-...erview-118922/

 

How do u know? What tests specifically?

 

I changed the oil a few days ago and looked in the old oil, there was no visual signs of coolant. The oil level has been staying constant. There is no signs of oil in the coolant, no air bubbles. No white smoke in exhaust. I think the oil pressure is a bit low though. ~17 psi idle at temp and ~40psi at 2,500 rpm at temp

 

That's not low. That's normal for an xj.

 

Ok, wasn't sure about that

 

You're either burning it or leaking it. If you have absolutely verified no leaks, you still need to concentrate on the possibility of a cracked 0331 cylinder head. It is a very real possibility here.

The best test for this is a "cylinder leakdown test". Other tests are hit and miss.

You should also remove the oil fill cap and with a good light, look inside and see if you can see any coolant leaking through a crack with a HOT engine, cooling system fully pressurized. The 0331 usually cracks between cylinders 3-4 which is within view with the oil fill cap off.

 

I just went thru this on my 00 WJ. There are 2 different ways this crack can show. Either between the #3 & #4 intake valves into the valve cover area, or into the intake passages. Mine started in the passages. I saw a little steam out the pipe, but it was really cold then so I didn't notice it much. Then it started dripping when sitting idling. I actually tasted the puddle and it was coolant and smelled that way. I figured I should do something about it before it got into the oil.

I bought a new heavy-duty casting from Odessa Cylinder Heads in Clearwater, FL, complete with valves, for $455, shipping paid BOTH ways (core return) and guaranteed for 5 years. The original head weighs 78 lbs and the new casting weighs 85 lbs.

Chrysler fixed this problem in 2002 and the new head has a "TUPY" stamped on it. They never admitted there was a problem in the first place!

 

It's looking like it's leaking into the exhaust when the engine is really hot, hence not showing signs when checked at normal operating temp. I'm going to do some more tests to see exactly what's going on and I'll make a post about what it was in case anyone wants to hear.

 

Sound exactly like a head crack. I assure u mine leaked that same amount, and it was indeed a crack...but I also noticed one of the "freeze" plugs on the side of my engine
Is leaking just a bit. Look at those its hard to see, Do it at night with a good flashlight. Just a thought.

 

See this thread:
https://www.cherokeeforum.com/f2/coo...gasket-158741/

A combustion gas coolant tester:
http://www.napaonline.com/Catalog/Ca...006_0361073538