Hello all. Looking to hopefully get some advice. I've been having a loss of coolant for months on my 2000 Cherokee sport with 195k miles. Everything in the cooling system has been replaced; radiator, radiator hoses, thermostat, thermostat housing, water pump, radiator cap, and coolant overflow tank (unfortunately all of those parts were leaking and needed to be replaced). Still somehow losing coolant. I did a combustion test, and it tested negative. Did a compression test, and everything looked fine ( 1. 130 2. 140 3. 140 4. 150 5. 140 6. 130). Not sure where to go from here. There is no visible evidence of leaking coolant. Oil looks fine as well. Any advice??

 

Cracked head. You have the infamous 0331 head, if I'm not mistaken. Do a combustion gasses test on your coolant to confirm.

Also send in an oil sample for testing to see how much coolant is there. You can't always see it.

You are looking at anything from just replacing a head, to a completely trashed engine. Coolant and bearings are not a good combination.

The sooner you get it done, the more likely you are to save the engine.

 

Forgot to mention that the head was replaced by the previous owner. But I will look into that as well.

 

Get a pressure test tool from your local parts retailer (should be available as a loaner tool) and put some pressure on the system. If it's an external leak it will be much easier to locate.

I had a slight leak once and couldn't find it - put the pressure tester on it and it was glaringly obvious that I had done a poor job tightening down the water pump after replacing it - I pulled it off, re-sealed it and checked it with the tester and everything was perfect after that. I wish I had just grabbed the test tool right away and saved myself hours of frustration.

 

Heater core? Does your windshield fog on the inside passenger side after you shut it off?

 

Or any smell of anti-freeze in the cabin? Or in the engine bay/at the tailpipe?
Excess water vapor coming out of the tailpipe is one way to tell, but only if it is drinking tons of coolant.

Maybe pony up some cash and send an oil sample into Blackstone Labs for a used oil analysis - they can tell you 100% if you have a cracked head or coolant in the oil

 

What kind of head did the previous owner put on? A TUPY Mopar new or used ? A Clearwater head or some other aftermarket? Or another 0331?