Since my truck is waiting on parts right now anyway, I figured I would go ahead and delete the catalytic converter. I've got some questions already.

1. Are the nuts on the flange where the downpipe connects with the rest of the system welded on or anything? It's so rusty on that flange that it's hard to tell what's going on.

2. Also, is the catalytic converter supposed to be clamped in right downstream of it? If so, mine lost the clamp somewhere along the line. I can't see a weld, either. It just looks like one pipe going into another one, without a clamp or weld, just sort of staying together by itself.

3. I'm guessing that that big muffler looking thing immediately downstream the skidplate is the catalytic converter. Right around the transfer case. Is that correct?

4. I realize that this isn't really a big deal or a big mod, but is there a write-up on this somewhere, it would be good to know that I'm not screwing anything up.

Thanks in advance for any help, advice, or comments, guys. I'm going back out there to work on it now. I'm going to hose everything down with penetrating oil.

 

The downpipe is clamped to the cat by a flange with two bolts/nuts and nothing else UNLESS the PO welded it or something. There should have been a clamp on the downstream side of the cat at one point holding it and the muffler pipe together. The cat is the big oblong thing that's only 18" long or so. Seems like most people had to cut at the cat/muffler pipe joint. I did. There was no way it was going to slide off, believe me I tried. I cut it as minimal as possible with the sawzall and got them back together enough to get the clamp on again.

When it's off, the body of the cat is filled with this honeycomb looking crap. Mine when held up to the noonday sun let through a speck of light smaller than a pencil eraser. I used a piece of bar and a hammer to beat it all out completely. It actually helped way more than I thought it would.

 

Okay, thanks for the help. I've got those two nuts soaking in PB Blaster right now. I think that I can probably slide that off, since it lacks a clamp and I expect that it's lacked that clamp for a while.

Man, those studs on the flange are rusty as anything I've ever seen. If I can't get those nuts off, I'll probably just dremel through those studs and put my new downpipe ahead of schedule. Do you, by chance, remember what size those nuts are on the flange studs?

 

Yep, like this ...

 

LOL, the studs just snapped right off. Whoops, haha. There was no way those things were coming off without snapping. It didn't even take effort to break'em. Also, I guess it's been leaking at that connection for a while, because everything at that connection has soot CAKED on it. It looks like coal was somehow deposited all over all of the studs and nuts. Yeah, and that connection where that clamp is supposed to be is NOT going to come loose. Should I cut it close to the catalytic converter or close to the rest of the pipe system? My exhaust system is rusted together so badly that it might as well be welded.

It does come apart at the flange where the catalytic converter meets the downpipe now that the studs snapped, though.

 

Leave yourself enough pipe to put it back in if need be. You never know.

 

If you live in a state that has emission testing you should leave the cat in place. You can pound the guts out of it......or weld a pipe inside from end to end for better flow. Most emission tests look for it to be in place. Some members here reported a sniffer test didn't toss up red flags either.
After you break up the guts inside the cat out, wrap a plastic bag around the opening then fire it up......fun to watch and profitable too. The scrapers might buy the guts for recycling.

 

I live in the great state of Indiana, so it doesn't matter whether or not the catalytic converter appears to be intact. I'm going to go and see if I can't get it off without cutting. Maybe some violent negotiations might convince it to budge.

More importantly, what should I do about the broken studs? Any ideas, besides new downpipe?

 

Grind/drill the old bolts out and buy new ones.

 

if the flange bolts through the pipe,(mine came with after market downpipe), buy two C clamps and use them to fasten it back on until you can get your new downpipe

 

That sucker is on there good. It might as well be welded. I'm just going to cut it.

 

I'm just going to order some 4" tubing from Jegs or something and have it clamped and later welded in.

 

Well, I got the cat off.

 

I'm doing a new DP cat delete soon I was told by Dale at Tymar to keep the Cat in storage because they cost $900.00 if you or someone needs one. As far as I know the new emmision laws do require Cats after 2007 on Light trucks including Diesels. Even Harley Davidsons have them after 07. Guy at work has 07 Cummins said he needs to spend mucho bucks to fool his computer to delete his cat or cats .

 

Yeah, I was thinking about selling the cat. If anybody here wants it, it's for sale. I have no idea what they go for, so just let me know. The flange where it goes to the downpipe is good on the cat side. The studs that I messed up are on the downpipe.

I'll probably update this thread with pics of the new piping that I'll rig up. It'll be janky, because it's just going to be a placeholder for the 3" Downpipe to 5" Straight Pipe system that I have planned.