2001 XJ Blackstone Labs Report
 

I have a 2001 Jeep Cherokee Sport with 196K miles on it. It has the original 0331 Head prone to cracking btw the 3 and 4 cylinder, so was admittedly nervous about my first Blackstone labs report (see attached PDF). No coolant, yay!!!!!!! I've looked through the oil cap btw the 3 and 4 cylinder and never noticed any green coolant, nor any bubbles, nor the TUPY stamp, so this comes a a pretty big relief/confirmation that the block is still solid. I am throwing a large evap leak code every once in a while on my OBD scanner, so know there is some troubleshooting to be had around the whole intake system for the silicon/iron issue. I do have a "cold-air intake" and throttle body extender mod where the original box was, so need to start there I think. Probably also clean up the throttle body and sensors around it.

The jeep was randomly stalling while driving a few months ago, but I seemed to solve that by replacing the crankshaft position sensor on top of the transmission's bell housing (side note: I now own about 30ft of ractchet extensions, lol)

Question... I have been watching my coolant level steadily drop over the course of the last month...incrementally and quite slowly... not to the point where I am desperately adding more each week, but it is noticeable by marking little ticks off on the reservoir. There are no noticeable leaks in the radiator or hoses, so where is it going? Can the coolant be atomized out of the exhaust headers? Long-term my steed is in pretty decent shape considering the miles, but I've always suspected the header is "leaky" and one of parts showing most wear under the hood (or at least by far the most rusty, haha).

Thanks for any feedback.

Is this the original radiator? From my experience working with them, one of the primary suspects for the small coolant loss is the radiator starting to fail. Often you can have a small leak from the seams of the radiator that doesn't even leave any puddles of coolant on your garage floor. Can't tell you how many times I have seen that.

It's time to get it up on a lift or get under it with the best light you can get your mitts on and look for traces of leaks. Sides of the radiator, weep hole in the water pump, edges of hoses. You're either leaking it or burning it and that Blackstone test is telling you that you are most likely leaking it.

Depending on the age of these components, replacing the radiator and cap, water pump, thermostat (195) and hoses can go a long ways in extending your reliability and helping you to sleep at night. The parts really aren't that expensive if you do the job yourself. Do a complete overhaul of the cooling system while you are at it. The money you spend on your cooling system is possibly the best money you can spend on your XJ. Especially with having the 0331 head that doesn't bode well on an overheat.

Good luck!

Thanks @tjwalker This is definitely helpful. Im 2nd owner, so unsure if the radiator is original or not, but my gut says it is. You're right that it's relatively cheap to replace the radiator and thermostat, etc... that'll be my next project... as soon as the 2 feet of snow melt here in Durango, CO, D'oh!

Any recommendations on aftermarket radiator and thermostat???

Looks like you have a decent oil leak to?

I bought a abused rusted out '96 for its 4.0, harness, and AX15 for a CJ repower project.
I had every reason to believe the engine was shot, but I sent a sample to Blackstone anyways.

Someone there must have a sense of humor.
The report came back stating "Engine is dissolved into oil".

my last XJ had a coolant leak at the front of the radiator, at the seam, its behind other stuff, no way to see it, never leaked coolant down as the area is hot and it evaporated...until the seam opened up a bit

the new one leaked out the water pump, but once i cleaned up my engine spotless, I could see a small green/white trail

the best way is to use a coolant system pressurising system

The report says you're putting in 6 quarts of oil between oil changes:

• For the Make-Up Oil field, please put the number of quarts added between oil changes.

I had the exact same concern.. 00 XJ with the 0331...losing about a quart of coolant every oil change. Rented one of those cooling system pressurizing dohickies and laughed out loud as coolant started peeing out the top of the radiator. A pinhole leak that was impossible to see and left basically no residue. Would never have found it without that tool.

well, I consider it a good problem to have relative to the known 0331 head issues. Radiator, hoses, and thermostat next up on the parts order list.

That's what the 4.0L normally takes.... 6 quarts. Am I missing something here? How many quarts does your 4.0 normally take during oil changes?

6 is the capacity.

I think that the confusion is that the "Make-up" field is for the amount of oil that you are adding in addition, or in other words between the changes. For example, my Dad had a 94 XJ he bought brand new. From the first oil change to the last change (slightly before it hit 400k on the odometer) he would have to add a quart of oil between changes. He never had an issue with the engine and after 400k it still ran perfectly (it ran perfectly on the day the Jeep was hauled away due to rust), it just used a quart of oil between changes. So he would enter "1qt" in that field. If you're not adding oil between changes, you'd put zero.

Well since he put 6 quarts I'm guessing he misunderstood the ticket for the oil sample and put how much he put into the Jeep upon oil change. Unless he has a pretty severe leak somewhere that he doesn't know about.

As the other guys stated the make up oil is for oil added to the jeep between oil changes to keep the level appropriate. They will use this at times to calculate values due to diluting the contaminated oil with fresh oil. The way it currently reads that in addition to the 6 fresh quarts at the oil change. you have added 6 fresh quarts.

Ah yes, thank you all for the clarification. Makes total sense. Just a typo on my end. Yeah, that's be pretty damn big leak if I had to give it 12 quarts ROFL. She's all good. I changed the valve cover gasket, rear main seal, and oil pump gasket w/in the last 10K miles. MY XJ should make it another 100K easily as long as I replace the radiator and thermostat soon.

Any one have recommendations on an aftermarket radiator for an 01?