0331 Head - The Ticking Time Bomb?

Well i've been reading on about this for a few months now (since I got my 2000 XJ) and I've come to realize that its not "If" its more like "When"

So I'd like to jump on it before I start to have issues. My Jeep has 125k miles, and I'm starting to wonder, what would be a good head replacement?

First off, is there a chance I have a good head? How would I check that?

I have been told that 04+? has a better head and will bolt right in? So i'll always be looking for one of those.

Also, For those of you who have been through this, what did you end up doing to fix this issue and how much did it cost? (even a ballpark)


Thanks guys,

Jeremy

Jeremey - I went through this last summer. You can search for my threads on this but I'll provide the following advice:
Pre-Replacement:

• Watch your coolant usage closely - I religiously check my oil, transmission, power steering and coolant levels everytime I get gas
• Send oil samples for testing - www.blackstonelaboratories.com - blackstone is a great source for testing - they'll send you the containers and all you have to do is send back an oil sample every time you change your oil to get an analysis - cost around $25
• Catch the issue early and it will save you a lot of headache - I caught it late but think I still caught it in time

Replacement:

• I used Clearwater Cylinder Heads out of Florida for my replacement head. It is a new casting with new springs and valves - reinforced in the area that is prone to cracking. It also comes with a decent warranty. I think my cost was around $400 - Talk to Pat when you call and he'll get you a new casting to your door in 3 days
• Installation cost for me was around $400 - so I'd expect to spend under $1k all said and done

Best of luck.

Pete

If you properly maintain the cooling system and engage in preventative maintenance by replacing the coolant and thermostat bi-yearly, and replacing water pump, fan clutch, or the radiator before they fail, you should never have any overheating issues. I watch the coolant and do the maintenance and have no worries about my 0331 head.

IMHO the 0331 head fails from abuse by lack of maintenance

Emerscape said:

Jeremey - I went through this last summer. You can search for my threads on this but I'll provide the following advice:
Pre-Replacement:

• Watch your coolant usage closely - I religiously check my oil, transmission, power steering and coolant levels everytime I get gas
• Send oil samples for testing - www.blackstonelaboratories.com - blackstone is a great source for testing - they'll send you the containers and all you have to do is send back an oil sample every time you change your oil to get an analysis - cost around $25
• Catch the issue early and it will save you a lot of headache - I caught it late but think I still caught it in time

Replacement:

• I used Clearwater Cylinder Heads out of Florida for my replacement head. It is a new casting with new springs and valves - reinforced in the area that is prone to cracking. It also comes with a decent warranty. I think my cost was around $400 - Talk to Pat when you call and he'll get you a new casting to your door in 3 days
• Installation cost for me was around $400 - so I'd expect to spend under $1k all said and done

Best of luck.

Pete

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That is the kind of thing I was looking for thank you.

Though I would hope I can save the $400 or so and install it myself, but I haven't looked into that much yet. Why did you decided not to?

Tim_MN said:

If you properly maintain the cooling system and engage in preventative maintenance by replacing the coolant and thermostat bi-yearly, and replacing water pump, fan clutch, or the radiator before they fail, you should never have any overheating issues. I watch the coolant and do the maintenance and have no worries about my 0331 head.

IMHO the 0331 head fails from abuse by lack of maintenance

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Thats what I would like to believe too, But i've heard of people (HEARD) who have had their 0331 head fail just randomly. But you are right, New water pump will be coming this summer.

My xj never overheated - ever. So I can't believe that the crack is purely due to overheating.

I chose not to replace the head myself for several reasons - limited experience, no garage space, and no time. IMHO - I've spent very little on my jeep up untill this past year and it's been good to me. It was money well spent.

what year jeeps got this head?

XJ-ARNIE said:

what year jeeps got this head?

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2000-2001 came equipped from the factory with the 0331 head.

collkid said:

...i've heard of people (HEARD) who have had their 0331 head fail just randomly. ..

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Probably the same people that drive around for weeks with 14 psi in their right front tire.

I have an 0630 head sitting on the shelf gathering dust. So far, that's all it is good for.

Tim_MN said:

Probably the same people that drive around for weeks with 14 psi in their right front tire.

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Didn't you read Emerscape's post just ahead these? Or are you saying he drives around with 14PSI.

You sound like Toyota trying to blame it all on the drivers. The 0331's are no good. And no, the don't ALL fail.

Oh, God, another 'lol 0331 sux' thread.

winterbeater said:

You sound like Toyota trying to blame it all on the drivers.

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Uh, no. There was a valid point raised about abuse of XJs with the 0331 head leading to failure. Chrysler's not off the hook for the poor quality of the heads by any means, but they're also ultimately not responsible for maintaining the vehicles once they're off the showroom floor. I'm not saying this to pass the buck, but it does cut both ways in this case. More:

The 0331's are no good. And no, the don't ALL fail.

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What this suggests to me are two things, both of which are related:

1) There needs to be a correlation between regular maintenance of the cooling systems and engine oil on 0331-equipped XJs, and;

2) What percentage of the failures occurred due to abuse and/or lack of proper maintenance?

I'm sitting at 157,000 miles on the original 0331 head in my 2000. Oil pressure and coolant temperature are good; there are no air bubbles in the coolant, mayonnaise on the filler cap, or any of the other usual signs of impending disaster. I've also kept the cooling system and engine oil maintained religiously, and the vehicle has never been overheated. It should not be inferred from this that I believe that my 0331 head will never fail, but rather that my experience in this regard (which is by no means unique) is contrary to a lot of the repeated positions on the subject, most of which I note are low on actual experience of either 0331 ownership or failure.

Note that I'm not arguing that there isn't a higher-than-average instance of 0331 head failure - there is. And I have no issue with the statement that the 0331 had poor castings, specifically around the #3 and #4 cylinder areas; this is a known fact. But what I would like to hear is what percentage of 0331 head failure was either caused by or accelerated due to owners simply not taking care of their vehicles.

Christ on a cracker!

Engines run on good old well water and non-detergent oils for hundreds of thousand of miles without cracking a head.

Yes, the owner is responsible for maintaining a vehicle.

NO, the head shouldn't crack. Overheat and warp--certainly. But head after head after head failing at the same 3/4 point? BS. Chryco should have been sued. Ford did essentially the same crap with their 3.8 L V6 and the headgaskets and they ended up having to provide extended warranties and repay owners for repairs that had been done.

There are no excuses for Chryco's FUBAR head.

What are the chances of head failure in my 98?

I've had a '00 for 6 years now. I've been reading posts on the '"0331 problem" ever since I found out about it. Here's what I've been able to take away:
It does appear to be random.
It SEEMS to randomly affect all months of '00 and some '01 engine production. However, the TJs built in '02(with apparently identical 0331 heads)don't have the problem.
Nobody(who's talking anyway)has done a systematic inspection of the heads that fail.
NOT ALL HEADS FAIL. It seems that most of them don't. No solid numbers, but probably under 10%, maybe less the 5%.
Most of the heads that crack let loose between 40K and 100K miles.

Based on the above, my guess is there was some flaw in the casting process, not the engineering of the head. 'Could be as simple as a flawed mold. Whatever it was, Chrysler (quietly)found and fixed the problem when they became aware of it.

To the O.P. With 125K on the clock, you're probably out of the woods, so stop worrying about it. Do you regularly check your oil? Start checking under the hood when you fill up with gas. That should be about every 300 miles or so. When you check the oil, check the coolant in the overflow bottle. If you start getting oil in the coolant, or coolant in the oil, then it's time to worry about it.

As for what to get, if you feel like you just have to have have a spare, there are a couple choices other then the aftermarket heads you can get. The older 0630 head can be adapted to your coil rail ignition, or you can start looking for a 0331 out of an '02 or later TJ in a junk yard(rare but getting easier to find)

Good luck and happy wheeling!
PS: my head's never cracked, bought at 47k, now at 112k

bought my '00 with 35K, cracked between 3&4 around 185K. Oil changed every 2k, coolant; every 6 months, t-stat; once a year, never over-heated. I thought I was in the clear too, when I started reading about this years ago. I'd say it's inevitable with '00-'01s. Abuse and neglect may just speed up the process.

If you have an 0331 head, watch your coolant reservoir. The #1 clue of a cracked head is coolant loss.

No, not all will fail, but this forum and others have plenty of threads of ones that have. Lack of good cooling system maintenance can contribute to the fail and an overheat of the engine increases the odds of head failure dramatically.

Along with adapting an older head which many have done, my understanding is that 2003 + heads from Chrysler have the "fixed" heads. These heads will be marked with the word TUPY somewhere on the head. Or you can source a head from Clearwater Cylinder Head or a handful of others that have heads that have reliable heads available.

So we have Emerscape and GreenXJ2K that have cracked 0331's without any apparent abuse. I bought mine with over 100K on it and I am sure that the head was cracked when I got it. It is certainly not a 100% thing that all will fail.

I also have a Crown Vic, which the crown vic forum says the plastic intake cracks on "ALL" of them sooner or later. At 125k, mine hasn't yet. (saying this will probably make it happen).

Just drive it and watch for the potential problem to come up. At this point, we can never know the true percentages, as most XJ owners are not on this forum and Chrysler doesn't give a shit about it any more. If I had to put a number on it, I would still guess at less than 50%, but more than 30%. But that is just a WAG.

03+ used factory heads will be fine. Just make sure they say "TUPY" between 3 and 4 where the crack would have been. You can probably pick one us for $60, and if you want throw another $200 for a 3 angle valve job and mill if necessary and you will be golden.

2 01 XJ here and know of a few more 00/01 with no head problems, Bad lifters yes, heads no.