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Quick exhaust manifold question 95-99

Matthew Currie

Matthew Currie

NAXJA Member #760
Location
Vermont, land of big clay
So my 99 (4.0) has started making nasty manifold noises, and when I looked, hoping for a loose nut on the exhaust flange, I found instead a very bad crack just above the flange.

I have a 95 that's being parted out a piece at a time, whose exhaust manifold is probably not too badly cracked, and might even be OK. It should be easy enough to get off, since I'm not being too careful about shearing stuff off it, and I figure if there are any cracks I might be able to weld them when it's off. So of course my question is, are these years interchangeable?
 
Cherokee tube style exhaust manifolds either have a crack, or will be cracked soon. If you are going to spend the time and effort to remove the exhaust manifold, you might as well install a new one. Welding a cracked manifold is a temporary solution until it cracks again. The APN manifold from ineedparts.com works well.
 
Tim_MN said:
Cherokee tube style exhaust manifolds either have a crack, or will be cracked soon. If you are going to spend the time and effort to remove the exhaust manifold, you might as well install a new one. Welding a cracked manifold is a temporary solution until it cracks again. The APN manifold from ineedparts.com works well.
Click to expand...
True enough, but this is a beater, 264 thousand miles, half the floor gone, etc. etc. I've gone so far as to buy it new tires for the winter, and a new front hub, but I can pretty well guarantee that it ain't gonna get a new manifold.
 
yeah, 91-99 should all be the same. I've never bothered checking years.

I've also never bought a new manifold. I just grab one of my random ones laying around, knock the rusted/busted studs out of the flange and tack weld in some 5/16" grade8 bolts, chisel the donut gasket off and stick a new one on, then toss fluxcore (or mig, depending on what the welder's set up for) on the manifold till most of the cracks are filled. Done this twice now with no issues, they might recrack but haven't yet, if they do I'll put another 50c in welding wire on them. The 98 will be getting the same treatment when I pull its motor for replacement sometime.
 
Note from DJ
I located this past post with Google search
joe peters flex pipe site naxja.org
Joe believed this helped
http://www.naxja.org/forum/showthread.php?t=1024506
Post # 10 by joe_peters
Just one more thing to do on that exhaust header--protect it.

Add a section of stainless steel flex tube between the downpipe and the CAT: http://www.cxracing.com/mm5/merchant...EXPIPE-250x8-E

This will eliminate (at least reduce) the torque on the exhaust header to prevent cracking.

Cutting and welding this you would need to take to a muffler shop based on your auto skill level. Do an internet search and find the best price on the 2.5" in 6" or 8" length and then just take it with you to the shop.
 
why do you put "note from dj" etc still? Your post has your username attached to it already...
 
unfortunately i have yet to see a 4.0 jeep exhaust manifold that doesnt eventually crack. im on my 5th one. so far i went through 2 stock manifolds, then and eldlebrock (every weld on that one cracked) and lastly my banks header developed two cracks 3/4 of the way around the tube. i learned the hard way to not waste a ton of money on expensive headers for jeeps as they all suck. back to a stock manifold now and hopefully it doesnt crack before i have to get the heep smoged in september. and the flex joint after the header doesnt make any difference, my last two (edlebrock and banks) still cracked and i have the flex joint on the down pipe
 
sorry that im mister doom and gloom, but after spending over a grand on 5 different headers i realized there is no hope for the 4.0
 
seriously, just booger weld the sucker back up. What do you have to lose? Maybe you'll have to do it again really soon, but it's 50c in welding wire, an hour or two of work, and a 5 dollar manifold gasket.
 
I welded up the one on my 97 TJ over 5 years ago, stock original one and not yet cracked again. I just did teh same to the one on my 97 XJ a few months ago... the gasket is like $10 and I already had the MIG along with the know how.
 
90% of manifold cracks are due to a bad trans mount, first the motor mounts go letting the whole motor and trans flex, then that rips the trans mount and let's them move even more wreaking havok on the header since it's basically hard mounted to the crossmember. most people change the motor mounts when they go bad but never check the tranny mount... chances are if your motor mounts are torn your trans mount is hosed too. replace both when you do the header and keep rolling for another 100k miles, the flex pipe is just a band-aid to the problem.
 
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