I own an 04 TJ and an 00 XJ. I am looking at an 01 XJ this weekend (just over 100k). Pics of the body and interior look clean and the asking price is in the ballpark. When I bought my 00 the PO had replaced the 0331 cracked head, cam, Timing chain, Water Pump etc.). He was a Chrysler mechanic and I know he did the job right.


I am going to assume that this 01 had and probaly still has the 0331 head. I know you can usually see the 0331 casting stamp on the edge of the valve cover but not always... any other ways to clearly identify the 0331?


How councerned should I be if it is an 0331? I know you read lots of stories about cracked heads but I am sure there are many people who run the 0331 with no issues ... people don't tend to post write ups of non-issues so quite naturally all you find online related to the 0331 are the negatives. Any advice on what to look for would be greatly appreciated.

 

i wouldnt take a free 01

not just cuz of the head.

 

Just keep the head cool and you should be fine. Make sure the whole cooling system is top notch with no weak links. One cooling failure and its toast.

 

Quick way to tell is if it still has the factory header and dual CATs under the intake. If it does, it is a 0331. If this is the case, look under the 710 cap for the TUPY markings. If it has this you are good to go.
FWIW, I have an 01 I just replaced the engine at 218k. Was not due to head, but because I dropped a core plug and overheated the hell out of it. I was not kind to it and the head was still fine.

 

Thanks that is helpful. I know the Tupy is a good sign but did not think the Tupy was used by jeep until 02. I though I read about three dots cast in the head on the 0331 seen through the cap but wasn't sure about that.

 

This was a useless comment.

 

he probably has his reasons, you should ask him why's that and then judge if it was useless or not instead of also making a useless comment yourself!

i'm guessing he refers to the less desirable coil packs and low pinion d30 among other things

like i've heard many times, it's not a matter of IF but rather WHEN it happens. they're all prone to cracking, it only takes one too many overheating for it to happen. i'd be concerned and replace it as soon as i buy the jeep. if the owner has never replaced it, i'd show him proof that it's an issue and use that as a bargaining chip to get the price down, and use that money saved to buy a clearwater head.

 

I asked a few reasonable questions about the head and got an unrelated and unsubstantiated opinion generally about that year XJ - that is useless.


But I agree about the d30 LP and coil pack as considerations. No too worried about that for this vehicle...and that wouldn't be a deal killer for me. This will be a highway only DD that I don't plan to modify.


I agree about using the head as a bargaining chip which is why I wanted to be able to definitively be able to identify it and was looking for help on how if I cant see the casting by the valve cover. I also wanted to make sure if it does have the 0331 what to look for as early signs of failure. This would be a deal killer. I will look over the cooling system closely and look closely at the head from inside the filler cap for what I can see but cracks can be hard to spot early on and don't always form at that location. And I assume if it has a slow coolant leak he would have topped it off and changed the oil to mask it.

 

you could tell us why!!

 

i got a

 

Mine got a performance cylinder head and a rebuild on the bottom end. That was nearly 5 years ago. No problems since. Not sure what your on about.

 

Unless he explains his reasons it's a useless comment.

 

Yep foolish comment. A cracked head takes what 5 second diagnosis? A 500 dollar fix. I'll take that over electrical gremlins that take weeks or longer to diagnosis or a rusted out mess.

 

That's not true. Someone could have swapped in a 0630.

To clear up some of the confusion that could be caused by what's been said in this thread:

All 2000 and 2001 4.0L XJs came from the factory with an original casting 0331. TUPY 0331 heads did not come into production until 2002, after the XJ run was over. If you find a TUPY head on a 2001, it's because someone already swapped it.

The most reliable way to identify the 0331 head is by the number cast into the head on the driver's side next to the #4 cylinder, just under the edge of the valve cover. Keep in mind that the beefed up Clearwater replacement 0331s also have that number cast into them, so it's not enough just to identify it as a 0331. The 0331 head also has holes tapped in it to bolt down the coil rail. If you see bolts holding the coil rail in place (as opposed to a homemade bracket), it's some flavor of 0331. See the bolt in this pic:



The common swaps are the Clearwater 0331, the TUPY 0331 and the 0630 from '99 and earlier. The first two are direct swaps. The 0630 requires a bit of light fabrication of brackets or a swap to a six cylinder minivan coil and plug wires.

The heads are not guaranteed to crack. There are people who have run them for hundreds of thousands of miles with no issues at all.

On the other hand, if you have a defective one, all the maintenance in the world won't prevent it from cracking. You can crack one without ever overheating it. It really just comes down to luck.

What you should do depends on you and your situation. There are really two approaches:
Personally, if it were my only vehicle that I relied on for work, I would go ahead and swap the head out on my timetable rather than having it crack later when I'm not in a good position either financially or time-wise to swap it. On the other hand, if I had other reliable transportation available, I would run it as is and watch like a hawk for signs of head trouble. Or if I were short on funds or time and saw no head symptoms, I would probably run it until I did.

One thing I do now for all my vehicles is get a $28 used oil analysis done at Blackstone at every oil change. In addition to seeing how the engine is wearing, the oil analysis will give you an early warning that coolant is getting into your oil, which is what kills engines. I would definitely recommend this for anybody who buys a 2000 or 2001 and doesn't preemptively swap the head, because the oil report can detect the leak before you see any other symptoms.

 

Thanks Extrashaky that sums up all the info I was looking for in one post. Very Helpful. I also have read that there is a casing on the top of the head with 3 dots. I am not sure though if it can be seen by looking through the filler cap. It might be too far rearward of where you can see without removing the valve cover.