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2001 XJ precat to manifold Leak Need Help


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2001 XJ with Dual precats, I installed a new pipe with the precats its made by Pacesetter USA 160.00 Free ship. Jeep had NO LEAKS the cats were old and clogged. I have leaks at the joints where the top of the pipe meets the iron manifolds. Leaks like b*@$£ feels like its in the back side of the joint. I loosened and tighted it several times to try to get it to seal. This is taper fit no doughnuts.


Any ideas would be welcomed as far as my skill level I have done many xJ engine swaps, so I have no idea why this is kicking my @$$. My health is failing and its really hard to get under and fight these bolts over and over. Hope its something stupid.

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Different set up but the same problem.


When I had the exhaust ran.........muffler shop cut the pipe just below the joint and then straightened the joint and then rewelded the pipe. IOWs the pipe is at an angle to the manifold/joint, that angle needs to be corrected. 

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I don't remember where, but I have seen this several times with other posts online in past years back about the pacesetter headers. I was in the market for 1 on my 88 4.0 mj. I ended up just getting a dorman from auto zone for the easy of warran, exchange, and price. I still have it no issues. Its about 3 years old now. I remember people saying they had the 1 piece manifold brought to a shop to be machined. In some of the pics online it showed those off by near a quarter inch. Like how did they not know it by a visual inspection? It was enough to scare me to go the simple route and nothing aftermarket xtreme. I still would like a nice complete exhuast. I never had one to see if there is a benefit on a 4.0.

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Are you CERTAIN there isn't a gasket between the manifold and y-pipe?


I've never done exhaust work on an OBDII XJ, but I can tell you that on the older models, the taper on the end of the exhaust manifold is actually a removable crush gasket made of metallic-fiber mesh. After a few years of rust/dust it tends to blend in with the manifold, but it needs to be replaced when doing exhaust work because after it takes a set it will never reseat quite the same. 


Looking online, there does appear to be something round between your manifolds and y-pipe but I can't find a part number for it:





Grab a chisel and give a LIGHT tap on the widest part of the taper (the base end).  If you can dent it or flake it, then it is a crush gasket that needs to come off.


If there really isn't a gasket, then your next best option, short of custom fab work, is to pack the $#!& out of the joint with exhaust sealing compound. Crude, but thats what the stuff is made for, and it should get you past inspection:


Versachem Exhaust Joint Sealer



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