Hi all, to keep things clear im gonna put all relevant parts i have for the issue below.

1999 jeep xj 4.0
stock horseshoe style intake
banks pre 99 header
stock downpipe(no precats since its a '99)
clearwater head

Ok, so lets dive into this... about a year ago, my header cracked hence the banks revolver header. My xj had a 0630 head when it was stock which is why I went with the banks header even though they dont list it as a fit for the 99. Fast forward about 4 months or so, I had a number of issues that led me to find a cracked head( yes im aware thats not to common for the 0630). I decided to get a clearwater head as that seemed to be the best option. Put engine back together and all was well untill about a month or 2 ago, when I started to hear a exhaust leak that I suspected was high up if not at the gasket from the way it sounds. I confirmed that today when I could see exhaust gasses come out somewhere around the middle cylinders exhaust ports/manifold tubes. As I found out about a week ago, the clearwater uses the 0331 exhaust ports. About now you might be realizing whats going on. I have 0331 style head ports, mated to a 0630 style exhaust header, and who knows what gasket with it. So my question is: What should i do to make the ports line up and not get a exhaust leak in another month or so. As i see it my options are as follows.
1. Buy a new header that mates to the 0331 ports( aka a 2000+ style header). Issue with this is that the rest of my exhaust is 99-, so id have to get at least a new downpipe to connect to the 2 outlets of the newer style exhaust manifolds. Not to mention i dont want to put the 2 precats on if not necessary. As im aware currently such a part does not exist to connect the 2 outlets to the rear cat without any precats.
2. Buy another new head thats a 0630 and sell the clearwater. Although this option seems like the better one, id much rather find a way to keep the clearwater if possible.

Im completely open to any input, hopefully parts that would work, Or a diy solution, anything. I can send pictures if you the reader are a visual thinker. If theres already a solution that people have mentioned in another thread, sorry. I have scoured quite a few threads in search of someone in a similar situation but so far have not come across any. Thank you in advance for any input.

Edit: i found these parts after more digging. Would these and a new shorty header for 2000 cherokee work in theory? Only modifications i can think of id have to do is weld the 2 extra o2 sensor ports shut. Lengthen the stock o2 upstream sensor wires to reach the intermediate pipe. And weld on a flange to the stock cat/pipe, wherever it lines up.

 

The problem is usually the opposite, a pre-2000head on a 2000+ exhaust pipe. It might be as simple as the correct gasket. You might need a intake/exhaust made for the 0331. Any idea whats in there now. Are you sure everything, meaning intake and exhaust manifolds are sitting/ sliding smoothly on the dowell pins and the pre mounted exh studs..sometimes they **** and don't seat properly on the head

 

Or you might need the gasket for the 0630...I have an older 01 motor kind of accessible in the garage...will see how an 0630 gasket bolts up...look up 0331 adapter plate in the internet. Its made to hook up EITHER an 0630 head to an 0331 manifold....OR a 0331 head to a 0630 Manifold. I think the problem is with the 0331 manifold because the ports and pipes are physically smaller than the pre 2000 manifold and the small pipes dont cover the ports on the bigger 0630

 

Looked around through old confirmation emails, looks like I have a 0331 gasket in it right now. Ill try putting a 0630 gasket in it tonight and see if it seals up properly before going the expensive route

 

so funny enough the clearwater head didnt come with the dowel pins, and i couldn't get the old ones out. At the time i couldnt find any for sale either, so i simply put it all back together with just a bolt through the hole to keep it aligned. So this could be a factor in the issue, if it slowly fell a bit.

 

My 2000 does not have ports in the y pipe, it is one sensor below the Y pipe on the intermediate pipe. So assuming this pipe is the same, no welding.
I would think a 0630 exhaust on a 0331 would work... Definitely see how a new gasket lines up first.

 

Rumor has is thats its supposed to work in that direction...its the 0331 small exh pipes on the bigger 0630 head ports thats the issue...not that many people go in that direction to put a weak 0331 head where a better flowing robust 0630 or 0720 head was.

 

https://www.cherokeeforum.com/f67/ex...estion-232707/

Looks like you want the -99 gasket.

 

correct im seeing the same thing, but if it came to it and i needed to buy these parts, the header id buy( not in the picture) has 2 o2 sensor ports, those are what id need to weld shut.

 

thats what I was kinda hoping for, my issue may be the alignment more then the setup itself. And ya ill be putting on a 99and down gasket on it today to see if that seals up better. In theory it should.

 

Just gotta let the jeep cool down, enough to work on, and ill let everyone know if it works out

 

Well, tore the jeep apart, and found something I didnt expect. The header cracked at the collector. Couldn't see it untill it was off. No signs of gasket issues. I guess the exhaust fumes were simply coming up through the holes between the intake and exhaust and the head when i checked. Called banks 10 minutes before they closed and within 5 minutes they placed a new order for me to replace it. Honestly very impressed with banks customer service. And to anyone about to ask, yes I have new engine mounts that I put in when I did the head swap. I might look into adding a peice of flex pipe somewhere on the downtube to maybe allow for more movement with the engine unconstrained by the jeep itself, thoughts?

 

Do the flexpipe, I have this header on two jeeps, one cracked, the other one I suspect has a small crack forming. Banks did warranty the first one, but I might just have the other one welded. I think it only has a 5year warranty.

 

I'm going on 5 years and 55k miles with an 0331 head in my 1999 XJ. The engine donor was a 2000 model year with federal emissions, so no pre-cats, just the underfloor cat like earlier years. It still had the later cast manifolds and a twin inlet y style downpipe like you pictured OP.

I have never had an issue with exhaust leaks. In fact, I don't even think there's enough of a mismatch to really affect the engine performance, at least not for a stock engine. Maybe if you've got some high RPM stroker build. Here's how the ports line up on a gasket that I bought for a 1999, but looks to be meant for 2000+ style heads.





The donor was a rust belt victim, and the front exhaust port sealing surface wasn't exactly pristine. I used some RTV on both sides of the gasket and haven't had an issue.



I intend to get a Banks or some other performance style header with more equal length runners for a better exhaust sound now that I've done a manual swap. I'll have a flex joint installed somewhere in the downpipe to reduce the risk of cracking the header.

For those of us with this oddball combo of later engine in an earlier chassis, running a performance 2000+ set of headers isn't a bad choice at all. It's probably a lot more crack resistant than the long 1999- style header. All you need is a custom midpipe that mates the two exhaust styles, and that's a good chance to weld in a flex joint in.