To start off; I have a 2000 Jeep Cherokee classic with the 4.0 I6, with 130,000 miles, and I'm very aware of the 2000 model year head casting issues between cylinders 3 and 4, and I have not pulled the valve cover YET to verify if there is in fact a crack. But from all other ways to tell, i do not have a coolant leak anywhere internal or external. no antifreeze in oil or steam from the tail pipe. once every week or two weeks i have to add almost a gallon of antifreeze. I am stumped. my main concern is my oil cap has a milky substance from what i think is condensation.

Also there is some sort of stop leak in the cooling system from the p.o.

Any ideas or advice would be greatly appreciated.
Thanks in advance,
matt2000xj

 

"my main concern is my oil cap has a milky substance from what i think is condensation."

I have seen posts like this before, it's usually not condensation. Chugging coolant by the gallon, unless there is a flood under the vehicle everytime you park it, the coolant is going through the motor. Stop by Autozone & borrow their pressure test kit and see what happens.

BTW: You can remove the oil filler cap and shine a flashlight in there.

 

i actually work for orielly auto parts, and am a parts specialist, and i've already done that to no avail. no leaks anywhere.

 

You can wipe the inside of the tailpipe and your finger comes out clean, no slimey mess? If we were friends I would not feel comfortable betting you there is a crack in the head. As a comparison I changed out my coolant in a 2001 about 10 k miles ago, I haven't added any yet.

Only other possibility is some homeless guy drinking your coolant when your not looking.

 

considering that i live in lakewood colorado, i wouldnt doubt that.

 

Same exact symptoms on my '01 in late 2009.
New head and no more disappearing antifreeze. If it is cracked it wont really open up till the head is hot, so a pressure test might not catch it.
Pull the #3 and 4 spark plug, if it looks steam cleaned you probably have a cracked head.
I too was putting a gallon in a week, only for 2 weeks though.

 

Do you drive short distances a lot? If not, you shouldn't have milky crap on the oil cap.
I didn't have any on the oil cap, but it took me an hour to clean the valve cover of all that sludge. My XJ had 38k miles at the time and also a lot of stop leak from the PO.

 

How hard was it to replace the head?

 

How long has this been going on for, whats the oil pressure like? You might want to insure you don't need to replace the engine. As far as difficultly to replace the cylinder head what is your level of experience?

 

I have done cylinder heads before on my 91 ford exploder, wasn't that bad. I know i would have no problem digging in. Its just the exhaust manifold bolts I'm worried about. Oil pressure is pretty normal, except my oil pressure spikes to 80lbs every once in a while. Which i think is my oil pressure sending unit.

 

If your going to replace the head just twist them all off & replace with new.

 

What are the chances that one of the exhaust bolts will break?

 

New update, i put the pressure tester back on and pumped to 17-18 lbs of pressure and left for about an hour and it lost 4lbs. But i can hear some sort of hissing from the upper radiator hose

 

Tighten the clamps and/or replace the hose and retest.

But if that is the real problem, you should see evidence of leaking or weeping coolant somewhere.

 

Update, i removed the valve cover today and found the crack, the dye that i put in the coolant made it really visible. it was almost 3" long. now its just the money i need to buy the cylinder head from my work. Now i am very against stop leak additives and head gasket repair, but to save the rotating assembly, i am going to use some cylinder head/ block repair additive and hope for the best so i can save for a few weeks. the p.o. already poured some kind of stop leak in the cooling system so i figure the damage is already done, so during the cylinder head r&r I'm going to flush the cooling system and use G05 as fresh antifreeze and replace the water pump and t stat. any thoughts?

and again sorry for being a thick headed pain in the a$$, and thank you very much for everybody's input, advice and patience.