2000+ head cracking

[falcon556]

Done some searching, it appears that 4.0 engines with a casting #0331 have the habit of cracking up between #3 and #4 exhast valves.
My question is, has anybody figured out exactly which years and models are affected? Did they ever fix it? When?
What is a direct drop in replacement for the defective heads?
These heads have the newer ignition system attachments and older heads will not work without modifications.

[jeepdude10000]

if u did more searching in this forum u would find the answer, it was answered about a month ago, if i come across it i will post the link.

[falcon556]

if u did more searching in this forum u would find the answer, it was answered about a month ago, if i come across it i will post the link.

I found all kinds of information, none addresses my needs.
I need to know whether 0331 heads were ever fixed, if so, what year, VIN,
casting #, anything. If not, how can a cracked head be fixed with a drop in
fix, without using another defective 0331. After reading pages of info, I didn't find what I need.
Unless of course I missed it.

[UNCC_99XJ]

Depending on who you ask depends on whether the 0331's started in 99 or 00. I've got a 99 with the 0630.

If you're looking at doing a replacement I believe the 0630's will match up, as well as the casting on the pre 96's...as long as it's a H.O. I could be wrong however.

[falcon556]

Depending on who you ask depends on whether the 0331's started in 99 or 00. I've got a 99 with the 0630.

If you're looking at doing a replacement I believe the 0630's will match up, as well as the casting on the pre 96's...as long as it's a H.O. I could be wrong however.

I have a 99 with a 0630 and 01 with the 0331. I think the 0331 came with the ignition rail in 2000.
I don't think that the 0630 can replace the 0331 because you need the attach points of the 0331 for the ignition rail.
This is why I am trying to find if it got fixed in later years or if there is another head from a 4.0 that will drop in.

[Fish'nCarz]

http://jeepsunlimited.com/forums/showthread.php?t=721472

[falcon556]

http://jeepsunlimited.com/forums/showthread.php?t=721472

That's great and if I have to I might go the same route.
OTOH if the problem has been fixed at some point, the solution is not to hang the ignition rail from the valve cover, it is to replace it with a head that will not crack.
His idea is great, I just can't imagining doing any serious 4X4 with my ignition
rail hanging over the spark plugs. That's why I'm asking questions here.
We can't call DC, they'll prolly deny everything.
Another reason that I need to know is that I may have to buy another XJ soon.
I will not even consider a 2000+ unless I know more about the head problem.

[x99j]

it does not effect all 0331 castings. the theory is their was a couple of bad runs unknown dates that were effected. the ones that do crack seem to only crack after significantly overheating. the posts i see don't seem to crack out of the blue. my build dat is 5/99 and i have an 0630 head with a distributor. they also continued to use the 0331 head on other models up till 03-04ish. if you look on e-bay or auto trader their are alot of 00-01's (0331's) with alot of miles on them. but i do not think you will get out of jeep what exact 0331 production dates are effected?

[falcon556]

it does not effect all 0331 castings. the theory is their was a couple of bad runs unknown dates that were effected. the ones that do crack seem to only crack after significantly overheating. the posts i see don't seem to crack out of the blue. my build dat is 5/99 and i have an 0630 head with a distributor. they also continued to use the 0331 head on other models up till 03-04ish. if you look on e-bay or auto trader their are alot of 00-01's (0331's) with alot of miles on them. but i do not think you will get out of jeep what exact 0331 production dates are effected?

OK, the only way to play it safe will be to stay with 99- on the XJs.
I'll keep an eye on my WJ in case it cracks up and I'll keep checking here for more info. Somebody may come up with a way to modify a 0630 to fit later models.

[Fish'nCarz]

it does not effect all 0331 castings. the theory is their was a couple of bad runs unknown dates that were effected. the ones that do crack seem to only crack after significantly overheating. the posts i see don't seem to crack out of the blue. my build dat is 5/99 and i have an 0630 head with a distributor. they also continued to use the 0331 head on other models up till 03-04ish. if you look on e-bay or auto trader their are alot of 00-01's (0331's) with alot of miles on them. but i do not think you will get out of jeep what exact 0331 production dates are effected?

I've looked into this alot, and writen to Jeep, as I had one crack on a 2001 xj. Jeep sez no recall, have a nice day.

I don't believe it was limited to "a couple of bad runs unknown dates that were effected." I think there is a defect that, while it may not be present in all #0331 castings, is intermittent enough that there is no way to tell if you have a bad one until it fails. I don't know if it was casting process, metal used, the molds themselves (by the way, there is not just one 0331 mold making all the heads from July '99 on), or the day of the week the casting was poured, but there is a problem over several years, and it only shows up after a good number of miles. Heat certainly may be an issue, almost certainly is. It seems very fishy that the same engines are prone to throwing the "misfire on cylinder #3" error code on hot restarts, doesn't it?

Mine puked at 49,000. Most seem to go at around 60,000 or so. One of these days we'll know what DC knows, but until then it is certainly a caveat emptor issue.

[falcon556]

I've looked into this alot, and writen to Jeep, as I had one crack on a 2001 xj. Jeep sez no recall, have a nice day.

I don't believe it was limited to "a couple of bad runs unknown dates that were effected." I think there is a defect that, while it may not be present in all #0331 castings, is intermittent enough that there is no way to tell if you have a bad one until it fails. I don't know if it was casting process, metal used, the molds themselves (by the way, there is not just one 0331 mold making all the heads from July '99 on), or the day of the week the casting was poured, but there is a problem over several years, and it only shows up after a good number of miles. Heat certainly may be an issue, almost certainly is. It seems very fishy that the same engines are prone to throwing the "misfire on cylinder #3" error code on hot restarts, doesn't it?

Mine puked at 49,000. Most seem to go at around 60,000 or so. One of these days we'll know what DC knows, but until then it is certainly a caveat emptor issue.

Chrysler must have figured out at some point that there was a problem and must have fixed it. I bet that the heads made after a certain year and model are OK.
At this point I see two problems.
First having a head that can go and take along the entire engine unless it is discovered early enough.
Second, if it is discovered early enough, there is no fix other than installing another potentially defective head. Can't even consider replacing it as a preventative measure.
Both problems are serious.
One of the things I like in XJs is that they are predictably durable.
You know where you stand. Unless you have a 0331 head that is.

[jimbow912]

I have a 99 with a 0630 and 01 with the 0331. I think the 0331 came with the ignition rail in 2000.
I don't think that the 0630 can replace the 0331 because you need the attach points of the 0331 for the ignition rail.
This is why I am trying to find if it got fixed in later years or if there is another head from a 4.0 that will drop in.

u can get ridof the ignition rail and put a destribeatr in that warks I have see it done

[Dave4.0]

I read on here about someone who made some sort of bracket to secure the ignition coil to a 0630 head.

It's tough to say if and when the 0331 head problem was fixed. Chrysler won't admit that it's a problem, and alot the newer model 4.0's are just starting to get into the head cracking mileage range.

For the record, the head on my 2000 cracked without ever being overheated, or abused. It literally just went. The coolant was flushed about a year before it happened and my Jeep was in excellent mechanical shape with all maintenance up to date. That's probably what pisses me off the most. I took good care of it and it let me down.

Knowing what I know now, I'd never buy another 4.0 Jeep that was made after 1999. In fact, mine will be going up for sale once I move into my new house in September.

Wow, I sound like a whiny bitch.

[avnsteve]

you should just give me that POS right now, hell I feel so bad for you and that crappy 2000 model xj, I'll give you my 88 in exchange...

[rebeltruce]

I just bought my 2000 XJ, I wish I 'd have seen this forum prior to buying it! I may have just fixed my 93 Grand Cherokee and put another 200K on her........I'm about to turn 79K on the XJ, so I guess I'm in the danger zone.

Right now she seems to be running strong...stays right at 210', I do miss my V8 though!

[falcon556]

I read on here about someone who made some sort of bracket to secure the ignition coil to a 0630 head.

It's tough to say if and when the 0331 head problem was fixed. Chrysler won't admit that it's a problem, and alot the newer model 4.0's are just starting to get into the head cracking mileage range.

For the record, the head on my 2000 cracked without ever being overheated, or abused. It literally just went. The coolant was flushed about a year before it happened and my Jeep was in excellent mechanical shape with all maintenance up to date. That's probably what pisses me off the most. I took good care of it and it let me down.

Knowing what I know now, I'd never buy another 4.0 Jeep that was made after 1999. In fact, mine will be going up for sale once I move into my new house in September.

Wow, I sound like a whiny bitch.

No problem, gimme $2000 (I'm not cheap) and I'll take it off your hands :-)
Joking aside, I have a 2001 WJ with that head. Close to 100K so far so good.
Not all of them crack, there were some faulty molds most likely.

[floppy]

wow chicken fricken little here man, the sky is falling... anyway I have 98k on my 2000 no problems, and I overheated twice in Vegas so it doesn't happen to everyone... relax a bit wow. If i didn't have a seasoned 2000 with 98k i would be scarred s-less right now.

[RyanM]

wow chicken fricken little here man, the sky is falling... anyway I have 98k on my 2000 no problems, and I overheated twice in Vegas so it doesn't happen to everyone... relax a bit wow. If i didn't have a seasoned 2000 with 98k i would be scarred s-less right now.
i hope you knocked on wood after you reply'd :D

just kidding, never seen it happen in person, but havenrt really asked any mechanics
got friend with 105,500 in a 01, 0331.

[Root Moose]

160,000 miles, 01 with 0331... Still going strong (knock, knock). I have a parts engine in the barn with a 7120 head just in case.

[RyanM]

when did the 7120's come thru

[Root Moose]

when did the 7120's come thru

IIRC, they are the "HO" head used between the RENIX years and the DC restyle/retool in 1997 (0630).

IIRC the 7120 and the 0630 are almost the same. I think if you search there is a post by Dyno that lays out the differences. For the case of correcting the 0331 the differences aren't signifigant.

Someone correct me if I'm wrong on that. I don't feel like searching/verifying. :P

[mtsz52784]

Ok finally finished... I replaced my 0331 head with the 0630 head tuesday night, mine cracked in between cylinders 3 & 4 and ran from driver side to passenger side. The 0630 head bolted up perfect and also got the exhaust adapter plate from a NAXJA member who has a couple more, plus brackets for the ignition rail. PM me if you want contact info and pictures of any part. I am very happy with my 0630 head and wouldn't trust another 0331 head no matter what year.

[Root Moose]

The 0630 head bolted up perfect and also got the exhaust adapter plate from a NAXJA member who has a couple more, plus brackets for the ignition rail. PM me if you want contact info and pictures of any part. I am very happy with my 0630 head and wouldn't trust another 0331 head no matter what year.

Always interested in new products and options. Post up pics and info if you can.

[mtsz52784]

The first two are of the brackets made... you have to make sure that you use the studded bolts so that after the bracket is on you can slip the washer, lock washer and nut on, The bottom original bolt you will slide into the hole on the bracket then into the ignition rail... if you can get your fingers underneath the rail after it is on all spark plugs then you can slip a nut on to hold in tight, but i opted not to, because it was a PITA to get the nut on.
http://matt-katie.com/images/ATT00008.jpg

http://matt-katie.com/images/ATT00011.jpg
The 2nd two are pictures of the cracked head, you can't see the crack but i can describe where it is. On the first one it runs from top to bottom along the right side of the left valve spring and towards the head bolt hole... the 2nd picture you can see a highlight of aprox where the crack is, runs from front to back... also this is all between cylinders 3 & 4
http://matt-katie.com/images/ATT00014.jpghttp://matt-katie.com/images/ATT00017.jpg

[mtsz52784]

Also since replacing the head and thermostat and using the exhaust adapter (PM if you need one), I feel that it has more power now and actually runs about 10 degrees cooler from the 210 it was running at.

[falcon556]

Also since replacing the head and thermostat and using the exhaust adapter (PM if you need one), I feel that it has more power now and actually runs about 10 degrees cooler from the 210 it was running at.

Why is the adapter needed? If the exhaust needs it what about the intake.
Pardon my ignorance but this is the first time I heard about an adapter in a 0331/0630 conversion.

[mtsz52784]

The intake ports are the same, just the exhaust are different, this adapter plate (PM for contact info) that a buddy got a machine shop to make up, will allow for a leak free-worry free exhaust and intake.

[falcon556]

The intake ports are the same, just the exhaust are different, this adapter plate (PM for contact info) that a buddy got a machine shop to make up, will allow for a leak free-worry free exhaust and intake.

It looks like the plate needs two different gaskets, the first looks like stock, the second like thin metal type. Where did you find that?

[mtsz52784]

that isn't a picture of mine... i used 2 stock gaskets (one on each side)

[MELKORsXJ]

i guess i got one of the short straws on the 0331 head... i purchased my 2000 XJ back in Jan. 07 with about 93,000 miles on it. i had talked to a friend about it, seemed great, and exceptionally clean. it ran at 210, which he said, and i have read was normal, so i didn't worry.

About the middle of Feb., i was on my way home from work, had been driving for about 7 minutes, and about 1 minute from home... my dash beeps at me, and the "check gauges" light came on. i looked at my gauges nothing odd, and then i saw the temp. it was about 220, and within the time it took me to think "that seems odd", i watched the needle peg the 260 mark... i Quickly pulled off the road and let it cool, added some water and drove home 30 minutes later.

while flushing the radiator the next day, my dad decided to check the oil... and he said, "well, we might as well stop with the flushing, we've got a bigger problem now." not exactly what i was wanting to hear, having had my jeep less than two months.

two weeks later, i rebuilt the head, and replaced several parts of the cooling system, except the radiator. (although i flushed it a good bit) the head had a minor crack, (i believe between the 3&4 cylinders) that was "repaired" by Dover machine shop, and was "good as new"... i hope it stays that way; because after reading about the problems of the 0331 head, i wish i had known about doing a 0630 swap, and i would have tried to do that, to be safe.

i've atleast another 1200 miles on the engine since the rebuild, and everything is running great. i haven't been losing any coolant, and my temp has been right at 195, as opposed to the common 210. (i have a 195 t-stat in, so that's probably why)

since the rebuild, i have been watching my temp very close, and it'll get a little above 210 on the trails, sometimes to the point of the acc. fan kicking on... i don't like seeing it get very far past 210, although i know it's not much to worry about, i think?

i like to take pictures of everything i do, so i figured i'd include a couple pictures of my head, to show where the "0331" number is located... i also marked out where all/any identification information was that i could find...

http://mslan.net/modules/coppermine/albums/userpics/10086/normal_0331%20head%20labled.JPG

here is a link to the full size image...
http://mslan.net/modules.php?name=coppermine&file=displayimagepopup&pid=601&fullsize=1

hope this helps in some way...

oh, and something funny, it took me and my dad about 2 weeks to take everything apart, get parts, and have the head machined... and it took me and a BMW technician from work 5 hours to completly rebuild it, including a run to Autozone, and dinner! ...and the tech had never worked on a 4.0 before :yelclap:

[mtsz52784]

Yeah same thing here, I had a GM tech help me do the swap who has never worked on Jeeps and it took about 5 hours to complete. That was also my contemplation... to buy another 0331 (refurbished) and wait to see if it cracks or buy a 0630 (used) and know that I really don't have to worry.

[MELKORsXJ]

had i known about the 0630 head, i would have tried to find one of those... but i hadn't found out about the 0331 head's problems untill now... so i guess all i can do is watch my temp and be extra cautious.:tears:

[Dave4.0]

If i didn't have a seasoned 2000 with 98k i would be scarred s-less right now.

Before my head went I sounded alot like you.

[xj_mike]

The thing that sucks is those of us living in CA really can't get away with a 0630 head swap due to having to pass a visual smog inspection. Having some brackets that would hold the coil rail on would be a dead give away that something has been changed. I think outside of that, it would be hard to tell but nothing is more of a PITA then not passing the smog test because of some damn visual thing (I know this personally).

I figure I will go with a HESCO head if the time comes. Expensive but it has a EO # and is CA smog legal. Adding 40 HP and dropping about 40#'s off the front doesn't hurt either. :D

[mtsz52784]

nothing of the emissions change so you should have no problems in CA. You could say the original bolts broke off when changing spark plugs and you created a bracket that does the same thing...

[floppy]

I looked up the HESCO head, $2,000 wow

[JNickel101]

Dayum....that Hesco head is sweet....

:lickout: :loveu: :worship:

but the price!!!! :scared:

[xj_mike]

nothing of the emissions change so you should have no problems in CA. You could say the original bolts broke off when changing spark plugs and you created a bracket that does the same thing...

True but if you get an a-hole of a tech that is by the book, it could come back to bite you in the a$$. Better safe then sorry and hey, I would love an extra 40 HP!!!

[falcon556]

that isn't a picture of mine... i used 2 stock gaskets (one on each side)

Are you sure they are exhaust, not intake ports?

[mtsz52784]

Yes they are the exhaust ports that are different, im working on getting a picture of the adapter, i forgot to take a pic before i assembled. If you look at the pic titled "0630 ports 1" that i sent you, and the "0630 exhaust overlay" you can see that it is the exhaust... also look at a header on ebay and you can see where the holes would line up on the head including the 2 in the middle that are right next to each other... making them the exhaust ports that are shaped different and this adapter plate makes sure there are no leaks with gaskets on each side...

[mtsz52784]

Anybody that wants more info, pictures you can PM me... ALSO wilsmick (NAXJA paid member) has taken the time to create a thread to discuss the adapter plate and info on how to contact him if you are going to do a swap and would like to do it correctly (as correct as a retro-fit can go)...

http://www.naxja.org/forum/showthread.php?t=919384


ALSO PM either of us if you would like any info if you are going to swap heads and would like some experienced input from this process.

Thanks Matt