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?

If everything else is working ok there's no reason a standard radiator replacement won't work. Don't fall for the 3 row hype. A 2 row or thick single row should work just as well or better than a 3 row.

I'm with Downs ^^ 100%. Update your entire cooling system. Water pump, hoses, fan clutch, rad, therm, etc.. with good quality aftermarket or OEM stuff. Its not very expensive and that 0331 will be just fine. Preventative maintenance my man! there are a LOT of us 0331's still on the road. Not saying it wasn't a thing, (maybe hyped a bit, I didn't just say that). just keep your engine cool. I saw a poll several years ago that showed 0331 failures...most where at or before 100k. so if it made it past that, then its prob good and you just have to not overheat it.

Ended up taking your advice @Savage71 and replacing rad, thermostat(195 degree), thermostat housing, upper and lower rad hoses, heater hoses, water pump inlet tube (modified here: https://www.cherokeeforum.com/f2/wat...5/), temperature sensor, flushed all systems really well (including heater core). Was not only cheap but fun and easy job to do. With the rad and grill out I was able to degrease a lot of the front of the engine, as well. Only thing I didn't replace was the water pump... hoping that doesn't come back to bite me later on. Also replaced coil pack and all new NGK plugs, removed and thoroughly cleaned the throttle body and installed all brand new IAC, TPS, and MAP sensors. Cleaned and re-oiled AFE air filter too + sanded and repainted the peeling AFE heat shield. Oil change with Wix filter and Valvoline Maxlife 10w30. Will def be sending another sample to Blackstone labs before next oil change to see if I can get improved figures. She's purring now!

...now it's on to new O2 sensors, new injectors, new leaf springs, new ball joints upper and lower, new sway bar bushings, new outer axle seals up front and a rear diff drain and clean....potentially new wheel bearings. Wheew! Love my XJ... it's always something!

Also fun project I will post pics of is thinking of mounting an ammo can/tool box where I deleted my A/C. Thank you all you veteran CF'ers for all your help, cheers!

Nice man! Thanks for coming back to the thread and helping to wrap it up for the next guy. Smart to replace those cooling system components! Let's loop @tjwalker in here cuz he and others were early in mentioning the same. I think most owners (esp with older vehicles) ignore the importance of keeping the engine cool.. then something fails or there is a seep (from the water pump for instance..nudge..heh!) and after a little while, things are getting a bit warm. I learned that a lot of ppl dont even look at their damn gauges! my father in laws civic blew an upper hose.. got so hot that the engine died.. he just kept cranking it... in the street.. over and over and over... like he just thought it was a fluke or something. blew my damn mind! dude totally ruined his car. Anyway man, my 0331 is still rockin..running cool at around 208ish and strong... 189k on the clock these days and sounds beautiful. Keep the shiny side up my man!