I replaced the mini-cats on my 2001 XJ over the weekend. This exhaust is more complicated and expensive than the earlier Jeeps, but doesn't have the manifold cracking problem. The exhaust components are flanged and bolted similar to earlier XJ's - no welds or pipe clamps. Depending on where you buy the mini-cats, the downpipe may or may not be included.
I had a heck of a time with the flange bolts at the exhaust manifold. There are 4 bolts with 15mm heads that thread into spring nuts that snap into the manifold ears. Because the cats are in the way and there is limited clearance, I found the only way to put a socket on the bolts was with a low profile 15mm socket and the shortest universal I had in my tool box. Even then patience and force were required to keep the socket square on the bolt. If anyone has any better ideas on how to do this, please let me know.
Also, I had a heck of a time just getting the mini cats in place while getting a bolt started. Three or four hands would be nice, but I managed. If anyone has any short cuts or tips, feel free to post them.
For reference, replacement bolts and nuts are
bolts - Mopar 6505754AA x 4
nuts - Mopar 6506546AA x 4
Also, the nuts at the downpipe flange were so badly rusted (probably because they are the lowest on the vehicle, my Jeep isn't badly rusted) that I had to cut them off. If you need to replace the bolts too, they are splined M10x1.5. Dorman sells a 3/8"-16 set of splined bolts that should fit (you will need two). Part number 03127. You can drive the old ones out with an air hammer if the pipe is held solid in about 30 seconds.
I had a heck of a time with the flange bolts at the exhaust manifold. There are 4 bolts with 15mm heads that thread into spring nuts that snap into the manifold ears. Because the cats are in the way and there is limited clearance, I found the only way to put a socket on the bolts was with a low profile 15mm socket and the shortest universal I had in my tool box. Even then patience and force were required to keep the socket square on the bolt. If anyone has any better ideas on how to do this, please let me know.
Also, I had a heck of a time just getting the mini cats in place while getting a bolt started. Three or four hands would be nice, but I managed. If anyone has any short cuts or tips, feel free to post them.
For reference, replacement bolts and nuts are
bolts - Mopar 6505754AA x 4
nuts - Mopar 6506546AA x 4
Also, the nuts at the downpipe flange were so badly rusted (probably because they are the lowest on the vehicle, my Jeep isn't badly rusted) that I had to cut them off. If you need to replace the bolts too, they are splined M10x1.5. Dorman sells a 3/8"-16 set of splined bolts that should fit (you will need two). Part number 03127. You can drive the old ones out with an air hammer if the pipe is held solid in about 30 seconds.