I have had several xj in the past. Last week my winter car (subaru) burnt a valve so I went in search of a jeep. I picked up an 01 last night with 150k. I remember reading about the 00-01 heads and completely forgot as I haven't had one in about 5 years. Well I was doing some reading today and it hit me about the bad heads. I drove it home about 1.5 hours and she done great. On my head its stamped 0331 but to the right a couple of cylinders down it is stamped 336 or maybe 3361 or 336u. Forgive my stupidity but what does this other cast mean? I was told the head had been replaced, but without paperwork I trust few. I looked and could not find tupy stamped on the head under the cap. I also understand that regular upkeep has a lot of do with problems. I did notice a external coolant leak but I think it may be a hose or pump seal. here are a few pics of it, I will probably video and put any upgrades or builds on my youtube channel Parlusk1791

 

That's a good looking jeep.

I think if your head has lasted 150,000 miles, then it probably won't crack. Some, even many, of the heads are prone to cracking but that doesn't mean all. Lots of these heads crack early on too. I don't think it's a mileage and maintenance issue as much as the actual head itself being weak. Some crack. Some don't. It's a relatively cheap fix that most at home mechanics can knock out in a day or short weekend. I say drive your truck and be happy.

I feel the same for the most part about the LP Dana 30 in the 00-01's. For the vast majority of people using their jeeps, that axle will be fine. But lots of people on here will try to tell you that your front axle is garbage and your head is gonna crack and your jeep is $hit and you should sell it and buy a 99 lol.

Just understand what you have and enjoy your vehicle. So maybe you can't run 5psi in your 35's and mash the skinny pedal on your locked LP30. Big deal.

And if you can't tell, I may or may not have some bias here as I'm driving an 01 as well hahaha. But my jeep makes me smile every day.

 

Thanks buddy. I am mainly gong to use the jeep for winter driving and a little trail riding. I was also told it has a front aussie locker, I will check and see if it does in a bit. everything else the guy said has checked out so far, quick disconnect sway bar, aluminum radiator, steel breaded brake lines, etc. So I we will see how she does. I am just glad to have something this isn't such a pain to work on. Subarus can be a PITA to work on.

 

I'd pick it up.. It's a clean jeep. You can get a heavy duty casting head for around $400 if it does crack down the road.

 

I think the other edge numbers are lot numbers that don't tell you anything about whether the head will crack. It's probably "336." The mark at the end you can't identify is probably the impression of a screw that was used to hold the number plate in the mold.

What you want to look for is a casting mark under the valve cover between the #3 and #4 cylinders. If you shine a light down in the oil filler cap and just see smooth metal (or a crack!), it's an original casting 0331 that is at higher risk of cracking. If someone has swapped in a later Tupy head, it will have "TUPY" cast in the head in that spot. If someone has swapped in a Clearwater head, they have a different mark there. All of the 0331 replacements have something right there where the originals like to crack, so that if you go looking for a crack you'll see their mark instead.

Most likely you have the original head. When people swap them, they usually make a big deal of that when they sell.

The original 0331 heads are maddeningly unpredictable. Some people have had them crack at 160K miles. Some have had it at as low as 80K. It seems like the guys who get to 200K have a pretty good chance of going the distance, but I still don't think I would trust it. Even if yours wasn't one that was going to crack on its own, it still has a weak spot, and mildly overheating it once because of a bad water pump or failed fan clutch might be all it takes to crack it.

If this is the original 0331 in it, you have options:

You can replace it preemptively with a Clearwater head. This is what I would do if it were my only vehicle, so that I could get the repair done on my timeline and not when the head decided to crack at the worst possible time.

You can just run it and monitor it. This is what I would do if I had another reliable vehicle that I could switch to if the XJ took a dump right when I was really busy or in a poor financial state. If you choose this route, you ought to get in the habit of sending an oil sample off for analysis at each oil change as an early warning for coolant in the oil. The oil analysis is cheap insurance ($28 at Blackstone) that will likely see it before you develop noticeable symptoms. Personally, if I had just bought one, I would pull a sample now (or after a couple of thousand miles if the prior owner just changed it) to see what's going on in there.

You could do a combination of both: Monitor in the short term while you look for a Tupy head in a junk yard to set up as a replacement if it cracks or when you feel like changing it. Tupy heads are not easy to find, but if you were to find one in a junk yard, you might be able to save a little money over the Clearwater if you have a good machine shop connection. In contrast, the Clearwater head comes ready to bolt on and drive, so to me it's worth it not to be gambling on a junk yard head.

The 0331 is the only thing seriously wrong with the '00 and '01 XJs. They also had the low pinion D30 up front, and all '01s had the dreadful California emissions with three catalytic converters and four O2 sensors. But you can work around that stuff, and they only become an issue if you start modding the vehicle or have your precats crap out, which they're not overly prone to doing. Fix the head issue and it's as reliable as any other year.

 

I picked up an '00 about 2 1/2 years ago pretty cheap. 147K. Running but not really drive-able, stock, older couple, second owner, neglected but not abused. Been fixing things and the more the Jeep behaved the more I fixed. Anyway. Did a 4 hole injector upgrade and figured while I was there would do the Valve Cover Gasket, clean the Throttle Body and IAC. Found the 0331 head in there. No TUPY stamping. Nice and clean. No milky looking oil hanging up in there. Do not experience an unexplained loss of anti-freeze nor little or no oil pressure at a very hot idle. Replaced at some point? Who knows. People seem to think this happens somewhere between 50 and 75K. Jeep dealership mechanic has told me the same thing. Wonder if this whole 0331 head is blown out of proportion. Thinking if the price right still not a reason to not buy an '00 or '01. Also it is a bargaining chip.

 

Not true. Most of the ones posted here are well over 100K miles when they crack. Mine got to 160K.

 

Not to hijack your thread, but, any advice on subarus from your experience. I'm looking into 05-09 outbacks and foresters for my wife's next car. Possibly Volvo awd wagons too.

 

Post that in the section for other vehicles.

 

I would say to read a Subaru board, not to be snarky, but because there's not going to be a lot of depth of experience here in regards to them. I own one, and it's a completely different species.

 

Like I said just what people have said including the Jeep mechanic. I'll be at 160K soon. Be nice to not have that problem.

 

If it has higher miles, make sure it has been maintained. They say after 05 the head gasket issues were fixed. Subarus are great vehicles and will last for a long time, not to mention they will go like a tank. the life of these engines are timing belts and head gaskets.

 

Absolutely he'll want to check on a Subaru tech forum.

In general the weak points on Subarus are the head gaskets on 4-cylinder non-turbo engines and the drive axles. Also the timing belt needs to be changed at the specified interval or hilarity may ensue.

I have a friend who recently purchased a 2004 Outback and had to have those items taken care of right away. I've read differing opinions on whether the head gasket issue was really fixed until the current iteration of their flat-four that uses a timing chain instead of a belt. (I think that debuted in 2011. When exactly the head gasket issue became a non-issue would be a topic for debate in a Subaru forum.)

 

Hey thanks guys. I'm looking into these things on some other boards now. No need to totally hi jack this thread lol. I appreciate the input.

Good luck OP