Possible cracked head?

I have a 2000 XJ with 108k on it. I bought it used with 64k on it. When I got it I found out that the head had been replaced at around 50k. They didn't flush out the radiator really good so it was pretty nasty. I replaced the radiator and back flushed the heater core.

Fast forward to today. I have babied this thing as mama said no wheeling this Jeep yet. I changed the oil today and found that I was 1.5 quarts low (from what came out). When I changed the oil, it came out HOT. I mean hotter than I remember it in the past. The oil filter was so damn hot that I had to use a rag to touch it. It came out BLACK with only about 4k worth of driving on it.

I just checked and noticed that my coolant reservoir is low and it's dirty. I stuck my finger in the coolant and pulled out a little bit of sludge. I stuck my fingers as far up the tailpipe as I could and rubbed around. My fingers came back dry and black as soot. I ran my XJ and cupped my hand over the tailpipe. It was kicking out moisture (my hand was getting wet) and black droplets.

I need to keep this thing. It's in AMAZING condition. I have a nice lift and tires on it. I've also got Bushwacker fender flares on it. I just had the front main seal fixed as well as had a Banks Torque Tube Header and O2 sensors installed this past spring. It's got a great stereo in it now. I mean, I really take care of this thing. Another reason not to wheel it, as it's gonna go to one of my kids here in a year or two. I'll get another TJ and wheel the piss outta that one like I did back in the day. Ohh, the trans shifts like butter. The day I got it I had the trans flushed at a dealership. Then I dropped the pan after soaking the hell outta the nuts with PB Blaster and changed the filter. Then topped it off with Amsoil. Plus I used POR-15 and rubberized undercoating on the belly. I put a lot into making sure that my XJ has been immaculately maintained.

Can anyone in here please help me out here in finding what's wrong with it? I think it's got a 210 thermostat on it right now. I was gonna swap it out with a MOPAR thermostat and new Mopar radiator cap. I don't know if it's the lifters going bad or if it's a cracked head again. I really don't have a lot of money.

Thanks in advance!

Is it overheating or driving rough? I'd start with a pressure test of the coolant system. It's free to rent the tester from the autoparts store. If you want to pull the spark plugs, a compression test could be in order.

You could also flush the coolant out if you see sludge. Stick your hose in the radiator and open the drain plug. Let it run for 15 minutes or so like that. Monitor your temps.

For the oil loss, do you see any leaking out? Check the back half of the block. It all ends up there since the motor tilts towards the rear of the vehicle.

No, it's not overheating, and I haven't noticed it driving rough. I talked to my dad who is old school. He's not as sure with EFI vehicles as his time was carburated. He said that a freeze plug could have went bad and should be checked. Also, he said that my old neighbor is an idiot for putting a 210 thermostat on my Jeep. He said to start with that and the radiator cap. I'm gonna flush the radiator as well.

I'll ask the local mechanic here if he can look at it to do a compression check. I don't feel comfortable doing that. I'm gonna have to really look up how to flush the radiator as it's been several years since I've done it. I am so bummed as I really love this Jeep. Many have offered money for this thing as it's been well cared for. Hell, I've had people ask me if I just had it painted. Nope, I used to detail cars, so I keep it clean and well maintained.

Thanks Ima Doit for the speedy reply. I'm looking for all the help that I can get right now.

Mopar thermostats are 195F and Jeep 4.0's normally run at 210F indicated on the temperature gauge. For model year 2000-2001 that came with 0331, the heads routinely crack on the top of the head and you can see it by removing the oil filler cap and looking straight down between the rock arms. Look for signs of coolant, "tan lines", etc. Google "cracked 0331". If this is the problem, the only real solution is to replace the head with another one. If coolant consumption is caught early the bottom end is normally fine. If left unchecked for a prolonged time, the coolant destroys the bearings, oil pressure drops and the engine becomes a junker. Its also possible that the leak is somewhere else, such a freeze plug, radiator, etc. If you want to know if coolant is getting into the oil you can pay a lab about $25 to test it. Hot oil in the summer time does not surprise me and I don't think its any indication of a problem as long as oil pressure is OK.

I recently dealt with a cracked head on my XJ. My symptoms were a rough idle and feeling of a misfire at idle but it felt ok when on the throttle. Before pulling the head I did a compression check which confirmed lost compression on one of the cylinders. I then pulled the dead and noticed I had cracks running between the valves on 4 of the 6 cylinders one of which was a lot larger than the rest. So do a compression check first before jumping to any conclusions.

Also a way I have tested to see if coolant is leaking into the exhaust is to pop the hood and with the engine running at temp give it some good throttle and then let it go and as you do this a few times keep an eye on the coolant reservoir and if you see bubbles that would indicate exhaust gasses getting into the coolant.

Thank you so much everyone for the great information. I'll take any and all advice that I can. I just went to the stealership and purchased a Mopar thermostat and gasket. Gonna swap em out. I also bought a new radiator cap from Autozone. I'm gonna flush out the radiator. The mechanic down the street is a solid guy . He told me to flush it out and just put straight up water in the radiator and drive it about 10 minutes down the road and back while keeping an eye on it. Then I can reassess it at that point. I also bought a new coolant reservoir.

I had bought the XJ with 64k on it. When I crawled up under the hood, I found a Mopar tag on the block. My buddy who worked at a stealership told me that that part number indicated that it had a new head. But they did a lousy job on flushing out the radiator. So, the reservoir was filthy. I washed it out pretty good when I put the new radiator in a few years ago, but it's still time for a new one. Not a hard decision as Autozone charged $27.00 for it and the stealership wanted about $75.00. I just hope that the new head was a better one that the one that had the issues.

Well, atleast with the 3.5" lift and 31's, it makes it easier to crawl up under there. :laugh:

The new head will be stamped TUPY if you look down from the oil filler cap. If it doesn't say TUPY and casting on the driver's side says 0331 its an original, defective, prone to crack head. Crusty doesn't explain loss of coolant.

I'm about to put the new thermostat in, but I'm unsure of the orientation. There's a small copper copper looking valve or whatever it's called the pushes in and out. Does that orient UP or DOWN? I apologize for the silly question, but I'd like to make sure it's done right. It seems that my old neighbor isn't the mechanic that he claimed to be as I've discovered some issues that he caused over time. So, I don't want to go by what's in the XJ.

md21722, will the writing of TUPY or 0331 be in larger writing? Where exactly on the drivers side will it be? Please forgive my ignorance here. I'm soaking up as much from y'all as I can.

The jiggle pin goes on the top. "0331" will be on the top of the head between the ports for cylinders 3-5. May be dusty or dirty so you may have to clean to see it. 50/50 Green coolant (ZEREX, AutoZone, etc) and distilled water is what you want in there. Some sediment is not a big deal, it will happen. Change the coolant every few years.

md21722, thanks again for the great information. I got it swamped out with the tutelage of my neighbor who is a mechanic. I ran some Barsleak coolant cleaner through the system. Completely flushing it out again in the morning. Then I'm gonna fill it with just straight 100% distilled water and then drive it around locally for a day or two to see if anything presents itself in my coolant system.

The good next is that my neighbor doesn't think that I have a cracked head. He didn't get much time to diagnose it, but after a cursory look, he was pretty certain. Were not sure why it's missing 1.5 quarts in just a few months and about 4k miles. I'm only changing it before 5k because I checked the oil and it was FILTHY dark black.

As far as identification of the head. I can't see anything on the drivers side from the top as the fuel injection and intake system are in the way. Do you have any other suggestions? My neighbor originally came over as he saw me outside almost inside my engine compartment trying to find it. The only thing I could find was two different sets of numbers on the top of the valve cover. On the left (passenger) side of the block, there's a MOPAR sticker that reads REMANUFACTURED PART with a partial part and serial numbers. When I got the Jeep, I gave the part number to a good buddy of mine who was a salesmen at a Jeep dealership. He told me that that part number was for a replacement head for my XJ. I confirmed that by having to shortly after that, put in a new radiator and water pump. I just couldn't get all the nasty sludge out of the original radiator. I just hope that someone in their infinite wisdom didn't use a 0331 head off of some other junker or something like that.

I'm curious now though to see what the side of the head says. The numbers on the Mopar sticker are partially worn away. The P/N is R56?0494 and all I have of the S/N is 1250.

Okay, I drove it around town and it the water came out a little rusty colored, but not bad. The reservoir tank had a bunch of flecks all over the bottom. Kind of looked to me like old broken up sediment that the cleaner must have broken loose.

So, I drained it and topped it off with coolant and took er for a spin. My temp stayed right at around 200-210. The needle was actually to the left of the black "210" line. I was doing about 55-60 mph the whole time. My oil pressure was at about 45 PSI while driving down the highway.

Normal??

That sounds normal but coolant loss is your problem right?

No, oil loss is my problem. I'm down 1.5 quarts in about 3-4 months and 3.5-4k miles. When I changed the oil it was filthy black. I don't know if this matters or not, but the last time the oil was changed, it was done at a local offroad shop. No complaints as they were great and came very highly recommended. I change my own oil, but they were replacing a front main and oil filter housing seals. The XJ used to leave puddles everywhere. Plus, I had them put in a Banks Torque Tube Header as well. I haven't noticed any puddles since. However, when I changed it this time, I noticed a drop of oil that had ran down the pan and was waiting to drop. I park it over roughly the same patch of dirt everyday, and again, I haven't noticed any dark spots.

Out of curiosity, when I added coolant, my reservoir is past the full mark now. It's about 3/4 of the way full. Should I pull it off and drain some of it out?

There's a place down the road who will charge me about $95.00 to do a "leak down test." I'd like to know if I'm burning oil, and if so, from where? Is there some internal issues that I need to be made aware of? These are questions that I'd like to get answered. I plan on giving the XJ to my daughter in a year or so. I'd like to ensure that it's running in tip top shape and I can resolve as many of the issues as I can before then. Otherwise, if it's still burning copious amounts of oil when she takes it, I can see one of two outcomes. 1. She doesn't get the oil changed in enough time and damage is done from running too low, or 2. She decides to be responsible and accidentally adds too much oil resulting in a James Bond smokescreen and my seals are blown.

I've addressed so many damn things and replaced a lot of the stuff on this XJ. It really is a beautiful piece of machinery. I've always thought that the XJ was the sexiest looking SUV on the road. Not to mention they can go pretty much anywhere. I can remember my dad telling me that him and my younger half-brother were out on the quads in the country about 20 years ago or so. He said that he could have sword that they were in an area that no white man had ever stepped foot before. Then they saw a clearing and a couple of XJ's parked in the distance. He said he was blown away that they could make it to where they did.

Disregard about the coolant level in the reservoir. I think it burped some more and sucked more into the system because it's now down to just above the "add" mark.

I just got off of the phone with Avondale Automotive in AZ where I was ordering a few small parts. The guy there squared me away AND he was able to find the missing number on the "Remanufactured Part" sticker that is on my block. The P/N is R5640494 and it's a MOPAR Remanufactured Head. So, I don't have the head that is prone to cracks. I'm gonna do the little things that are cheap to do and hope that solves the problem. I have the PCV elbows and hoses coming to swap those out. I have a bunch of oil built up on there. I detail the engine once or twice a year, so I know it's not years of built up oil.