A2000cherokeexj

Just recently purchased a 2001 xj on a deal I couldn't pass up. It has 150k miles and still has the original 0331 head. Did all the normal checks before purchase, no milky oil, 50psi underload, 30 psi at idle, no bubbles with Rad cap off, looked inside valve cover no substance no bubbles just clean. Now my question is, if its gone 150k holding together should it be ok? I'm trying to decide where to spend my money first. Lift kit and just keep a good eye on it, or replace head and call it future proof? What would you do.

fishtaconc

Do you have any record of the maintenance, especially the cooling system? The cooling system condition will be the determining factor as to how long the had will last. If you do replace the head, with say an '03+ 0331 "TUPY" head or similar aftermarket head, the cooling system needs to up to snuff. Either way you are one overheat away from serious damage.

DFlintstone

A short answer is no. I wish I saved it, (or could find it). Somebody here on the forum compiled data and put together a list of at what mileage,(s) the 0331 failed.
IF I remember 140, 160 was right in there with the most failures. (135?) You might find it with a search w/milage. In any case you are not gonna "get out of the woods" on that. I guess overheating is something you really don't want to try. Hoses start looking pretty cheap, and anything invested in the rest of cooling system is money well spent.

A couple of guys have posted that the new carbon fiber stop leak actually worked for them on that. No idea if that was fraud or what, I just mention it because a seller might possibly have done something like that with yours.

I was disappointed in the statistics that although the mileage of the failed 0331's was covered, the actual #, or percentage of them that cracked....I haven't seen.

Myself, I'm pretty cheap. It's really rare I will fix something that works, am plenty busy dealing with things that don't!

Edit>(added). I haven't seen it, but saw posted the "tupy" mark on the "revised" 0331's is located somewhere inside, on the head under the oil filler. ???

tjwalker

There is absolutely no way to determine if your 0331 head will crack.

Will all of them crack? Absolutely not.

An overheat virtually guarantees it will crack though. So be darn sure your cooling system components are up to snuff.

But even with the best of maintenance and no overheats, this head absolutely can crack.......

A2000cherokeexj

So I'm in the most likely mileage for it to happen that's fun. Cooling system was pretty nasty brown, but I think that's BC they mixed go-5 and the green stuff. Had it flushed straight away, stays 190-210, jumps to 220 when sitting but I haven't heard the auxiliary fan engage so that needs to be replaced. I'm 95% certain it hasn't been cracked even if they used a stop leak there would still be residue under the valve cover I would think. Been looking at clear water heads would run me 450. Anyone have a junkyard Tuppy rebuilt? How much did it run you? I don't like to fix things that aren't broke either but this sounds like a time bomb that wont make it too 300k.

DFlintstone

Yea....no idea if it's one out or 3, or one out or 300! Guess you do have some control of lighting the fuse or not. I guess the e-fan relay is grounded by the PCM when you turn on the AC, also when you turn on the defrost, as well as by the temp switch. I'm not positive about the defrost. It's a pretty high temp, 217*?

Oh, and. Finding a tupy head would be sweet, but you can go with about any head, at least from 97 but maybe earlier. You need to fab/fit the bracket for the coil packs is all.

413maxwedge

I would take an put 400-500 bucks away just in case it does happen (or just do it now and be done). But first thing to do is, if you got a model made roughly mid year to the end of the year you might have wound up with the good head.(TUPPY)
Once that cash is put away then start on the mod's you want to do to your XJ.

413maxwedge

Its a bit more work than just a bracket for the coil packs, which needs to be built good enough to remove most of the vibe's those don't help the life of the coils to much thats why they have four bolts holding it nice and tight. Anyway you forgot the exhaust dont fit right the intake don't fit right either with any other head.

A2000cherokeexj

Unfortuantly I do not have a Tuppy, no makers mark. lm still so surprised this head never had a recall. I think I will set aside the money and save up for a headers as well..if I have to go through the b*** of am effort to get that off I might as well. Yea I looked into earlier heads I don't have the means to Fab much so a direct bolt application is my best bet. Atleast this xj is worth the money, she's pretty.

DFlintstone

Thanks Max! Know plenty have done it, didn't recall that you need to grab the manifolds as well...

NICE! A2000. Might be tough finding that tupy, and myself I don't think I'd want a welded "reinforced" 0331. I think you can buy the bracket, and mounting it consists of drilling and tapping some holes......

And, yea guess it was during the WHOOPS ! year the tupy came out. I haven't seen one, it might not be easy to see, (not directly under the cap), but down in there somewhere. I really don't know, but I would take a REALLY good look.

EDIT! changed 97 to 01 ^

fishtaconc

Actually it was late 2002, yesterday I looked a 2002 WJ (9/02) build date had a TUPY head. If you are looking for a jy TUPY head, look for a 03+ wrangler.

tjwalker

This is my understanding as well. Late 2002 for TUPY.

To be sure, look through the oil filler cap and you should be able to see or not see the TUPY marking. That is a quick way to verify.

A2000cherokeexj

Unfortuantly it seems no wranglers exist in junkyards around here. Probably going brand-new

DFlintstone

I found this and saved it months ago. Don't remember where I found it though!
?????????????????????????????????????????????????? ????????????????????????
The heads that had trouble were the early #0331 heads (1999-2001WJ/TJ, 2000-2001XJ) before they were revised in late 2001 (revised heads have the "TUPY" foundry mark.)

1998 will have the #0630 head, which is typically subject to uncommon individual defects rather than a class-affecting problem.

jamurrin

Great thread that gives the basic info...
https://www.cherokeeforum.com/f2/00-...erview-118922/