2000+ head cracking

[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.

 

[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 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 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.

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

 

[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...

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.

 

[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...