When the engine was getting rebuilt at Hall's, Greg noticed that the catalytic converter wasn't heating up, which means it isn't functioning correctly. (A cat needs to get to at least 600 degrees to really work well in terms of emissions control, though they can run as hot as 1500 degrees without damage.) Unfortunately, excess heat can lead to other interesting side effects. Here's what I found when I peeked into my old converter.
Not exactly an effective set up. I'm kind of amazed that the thing passed emissions with this. How bad does one of these have to be to fail?
My new Magnaflow cat from BJ's is a great replacement for the original one. It's CARB legal, which is a requirement here in California. I know this thing is old and sucks gas, but I still want to have a clean running rig.
Since a converter change was necessary, I decided to go whole hog. Earlier this year, I'd noticed just how truly lousy the welds were at the joints of the exhaust system, including the AIR return tube from the cat back to the exhaust manifolds. Here's the 3"-to-2 1/2" neckdown transition from the Y-pipe to the cat. Ugly. I have a more elegant, or at least less messy, solution that I put into practice today on the other side of the cat, which I'll get to later. This one stays for now, however, because I will be having Hall's put on a pair of Doug Thorley headers with a 3" Y-pipe, which means this junk will be going bye-bye then.
Here's my muffler, which I've come to understand is not stock/OEM. This one is quite long (~30") and looks to be a no-name brand. For better or worse, from the cat back this thing was one big welded chunk, so I had to remove it first.
First I popped it off the cat. Luckily, it wasn't welded up, just a normal exhaust clamp. Before I went to work on the door lock fix this morning, I hit the nuts with penetrating lube to soften the rust up a bit. It worked well.
Then I had to get it off the hanger clamps at the back end. Here's my son, Nath, helping me get the job done. He's a lot of fun, of course, and he knows his way around tools enough to get me the sockets or wrenches I need. When I'm stuck under the Jeep, he's the best helper there is. (Note, as well, the kinks in the exhaust pipe and the broken weld tabs out by the exhaust tip--this thing was never a quality product.)
Because it's one chunk and I didn't feel like going to town on it with my Sawzall, I worked it forward, rotating the tailpipe over the rear axle and then pulling it out under the driver's side door. Easy. The cat also was simple to remove, again just an exhaust clamp holding it in place.
Then it was time to get with the installation. Unfortunately, the neckdown transition pieces I ordered from Amazon.com were 3" inside diameter rather than outside diameter. That meant they wouldn't slip inside the muffler and catalytic converter tubes as I had hoped. Instead, they were the exact same dimensions as those tubes so I needed to get some 3" o.d. and 2 1/2" o.d. exhaust pipe to get the job done. I went to O'Reilly's with Nath but had no luck. The counter guy there steered me to Redlands Muffler & Brake. My plan was to buy some pipe. The owner of the shop was just hanging out when I came in. He and one of his employees dug through their cutoffs and pulled out two pieces of the right diameter. When I asked how much, he said free. It's nice to meet people like this. He didn't need the scraps he gave me, and he didn't need to charge me either. A good man. My neckdown transition is the middle one in the pic below. On its flanks are the scrap pipes he gave me.
First thing I had to do was cut them to the right size, so I laid out the kit I bought from BJ's Off-Road side by side with the old muffler (sorry, no pics) to get a sense of the length difference, which was about eight inches, the length of my pipe adapter. With my dremel, I cleaned up the edges of the scrap pipe and then popped them into the adapter before cutting them down. Here's what I had at that point.
Once I knew the length I needed, I scribed a line, put the pipe in my woodworking vice (only one I got, for now), and then went at it with my Sawzall. Here's what I produced. I cleaned the edges of the cutoffs again with my dremel. I have the parts to build a second one to replace that welded up junk mentioned earlier. When I deliver the rig to Hall's for the headers, I'll drop that off, as well. Hopefully it won't make the system as a whole too long. If so, they'll have to fab something up.
Once I could put the system together, I threw on the cat and tightened down the exhaust clamp finger tight so that I could move it around as needed. Then I slipped on my new adapter pipe and the muffler. The weight of the muffler was causing everything to hang down way too far below the frame rail, so I used my jack to get it back up into position. With the custom bent exhaust pipe from BJ's that is designed to get over my rear axle, I jacked everything up until the muffler was level and I had good clearance at the back end.
I was able to reuse my existing hangers, which was nice. This one I'd put on about a year and a half ago because the old system knocked against the track bar extension bracket (in pic at left). I think I'll go back under there soon and lop off the inch or so of bolt sticking out to the right of the bracket housing on the axle, just for the extra clearance.
3" pipe meets for 4" chromed exhaust tip. Again, I was able to reuse the hanger that worked with the old system. I just had to rotate it a bit since this pipe goes a few inches farther back than the old one.
Here's my 3"-to-2 1/2" adapter in action. I could pay to have this all welded up, but I like the flexibility of the clamps for now, especially with the Thorley headers going on soon. There might be some fitment/length issues that will need to be accounted for when all is said and done. That band clamp works quite well, and the other two clamps are positioned perpendicular to each other so that the nuts are easier to loosen or tighten.
The entire thing, tucked up snug. It sounds great. Not terribly loud, but a nice, deep rumble. I'm sure it's going to be great. And with the headers on, I might even get a bit more power and efficiency out of the engine. One can hope...
