My 1990 Cherokee 4.0 165K has been losing coolant for quite some time and I can't find the source.
I have to routinely add collant to the bottle.
Don't see any visible leaks and have replaced the thermostat, hoses, bottle and cap, water pump, radiator.
Have done a compression check and it doesn't look too bad between the cylinders.
I have been told that any head gasket problem would make it run awful. It does have a less than perfect idle.
Have done a coolant check for combustion and it doesn't show up anything.
Don't see any coolant in the oil or smoke or coolant coming from the exhaust.
I was told to look at the freeze plugs as a culprit.
Any other ideas and help are appreciated.
Thanks.

Do a pressure test on the coolant system,you can buy the tester at the autoparts. Mine had a small head gasket leak and ran fine for several months.

I have done the coolant pressure test and it loses pressure very slowly just like I figured it would. I still don't see any visible coolant leaking out anywhere. I still suspect a small head gasket leak.
I will pull and inspect the spark plugs again and do another compression check.

dumb question, but have you looked at your oil color? if it looks like chocolate milk it def head gasket or cracked head. any rust on dip stick?

just something else to check

also is your pass floor wet at all? could be a leaky heater core too. those are two good spots for coolant leaks to hide.

I have a 2000 xj, and have identical symptoms to dcspacone. But I have some rust on my dip stick. No "milk" IN my oil, however i do see it around the oil cap.

Head gasket???

No chocolate milk oil, no heater core leak on floor. Have added Barrs Stop Leak to the coolant to seal a Head Gasket etc.
Waiting to see what if anything that does.
Does anyone have any recommendations on coolant additives if this does not work? I'll try anything before yanking the head off.

Thanks.

http://www.jeepsunlimited.com/forums...d.php?t=391831
Have a look here there's a lot said about 2000 and 2001 4.0 0331 heads

Its only a difference of ten model years.

To the OP: Try a leak detect kit with the UV Dye. That may help if its external if not then well you should know what needs to be done.

Mine leaks around the over flow bottle cap,it dosn't seal right.Time to up grade.

Time for one of these, http://www.summitracing.com/parts/CT...1/?image=large