Hey, the cat back part of my exhaust has rusted out, and I was only able to get from the front of the cat unbolted, sawing through one of them. Trying to get the bolts from the rear of the cat is proving impossible. The nuts and bolts are so rusted their true size is now smaller, and I can't get a wrench or ratchet to fit.

In your collective wisdom, am I wasting my time trying to get it unbolted, and should race right out and get a new cat, or wrestle or drill or vice grip my way to getting this thing apart? I have never seen anything this badly rusted or stripped.

Any thoughts appreciated. Am I missing out in the ancient Egyptian method of cat removal?

Thanks

Save the cat. Destroy the bolts. I find careful use of an angle grinder can take either the nuts or bolts out. Then use a punch and a hammer to clear the remains of the hole. If it is really really rusted sometimes you might need to heat the bolt remains to unfuse them. New cats are expensive and don't work as well as OE.

x2 on what Jordan said, if you can, try to sacrifice the bolts and angle grind/sawzall them to separate the two.

If it doesn't work out I just removed the cat from my SPG (PA antique plates FTW!), you're welcome to it if you just want an OEM replacement...

Federal law says you can't sell used cats (you can't buy them at the junk yards) - so if your OE unit is still in salvageable condition and you want to keep the cat converter, or need to for inspection purposes you should do as Jordan says. Cut the bolts off with an angle grinder, and then blow them out with an air-hammer then install new.

Thanks for the hints guys, i'll go the angle grinder route, and if no dice then I'll take Hutch up on his offer.

I definitely need it for emissions here in MD, as I'm not running historic plates. Its a little funny, it passed emissions inspection 2 months ago without issue, i'm surprised they didn't flag me for it being loud.

You call that rust? That looks like a year old New England car!
Those look like they'd come apart if you warmed them up with a torch and used vice grips to turn them. Or cut them with the angle grinder and a thin cutoff wheel.

DeLorean wrote:Federal law says you can't sell used cats (you can't buy them at the junk yards) - so if your OE unit is still in salvageable condition and you want to keep the cat converter, or need to for inspection purposes you should do as Jordan says. Cut the bolts off with an angle grinder, and then blow them out with an air-hammer then install new.

Yeah I was somewhat doubtful I'd be able to ship it... but thats crazy you can't even sell them.

Scott just let me know if you want it, I've got no use for it. You're down in MD, right? I'm not too far away so wouldn't mind a nice weekend drive in the vert to get it to you.

You could always cut off the bolt flanges, and replace them with a commercially available flange, that you weld on.

Or just weld it to a length of pipe, and make a slip joint with a clamp.

or just weld it solid to the pipes.


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I found an angle grinder i hope will do the trick. I like the idea of welding on new stuff, but its outside of my current skills.

Hutch, i'd be glad to take you up on your offer in case it all goes wrong, but won't be around much this weekend, how about the following? I hear you on riding in the convertible, i'm missing mine during this nice weather. Oh, i am in maryland, near frederick, but i'm up around westminster often.

Thanks all

Angle grinder for the win! My father in law has an air powered one that worked great.

Hutch, I'm still interested if you are in getting the cat you took off. I'm a big fan of having a spare.

Spent the day at the renaissance festival. Boy was it hot, but the kiddies had a good time. Any of you ever seen Jonny fox?