I have a crack in the output pipe of the Catalytic Converter. Its cracked right where the 1st muffler clamps on. I've uploaded a sketch to the "Cars" gallery.
Any fix ideas?
Clamp a sleeve over it?
Cut it out and weld in a new piece?
Replace the CAT?
Thanks,




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'90 245 295k, '93 945 308k

There are muffler shops that can easily make a small repair pipe for you.

I think that Maremont is one brand.

Make an even cut before the crack and remove the remains from inside the other pipe, then have them make a small repair pipe that fits both ends that are left.

From your diagram, I would go from outside to inside.

You could measure and have the repair pipe made before you take things apart.

I have a nice exhaust pipe cutter that is a pipe cutter with 4 cutting wheels and a handle that looks like a screwdriver. I only have to swing it just over 90 decrees to cut a pipe - very handy!

See - http://www.harborfreight.com/exhaust-pipe-cut-off-tool-69327.html

I have a nicer one than the picture - it was the easiest picture to find.

image submitted in "personal" gallery

img src='/GALLERY/images/11504.jpg

http://www.jbweld.com/product/j-b-highheat/

It's good to have around for other stuff too. Moisten your fingers with water during application to smooth it.
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1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

all due respect......... it won't hold up and qualifies itself as the most short term solution possible or on the level with furnace cement

Cat with integrated pipe used on the later 240's is stainless, I believe.

Also the cause of the crack needs to be addressed for even a sleeve or real weld fix. Something has put stress there. It might be as simple as failed donut hangers on the resonator.

I might use a bandaid after addressing the root cause, just to postpone the real repair until warmer weather. This stuff might "seal" and get you/him by if the cat back system is hanging correctly.







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Art Benstein near Baltimore

"The realm of preconceived notions is not a friendly place to have an opinion."

how did I know Art would ask a question like that? This is actually on my 940. Doesn't appear to be stainless as its all rusty but I'm not a metallurgist. I could try a magnet on it. All hangers are accounted for. Its possible I over tightened the clamp last time I installed a cat-back. ? Or perhaps 310k miles of salty wisconsin winters finally took its toll.


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'90 245 295k, '93 945 308k

Oh, a 940. Well, that prolly doesn't make any difference -- My beliefs about the composition of the pipe are based on just what you said -- it has the original through 300K of salty exposure, while the rest of the exhaust system may have been changed several times.

Dunno if the nickel added is enough to keep keep it shiny, but I checked my stash of old cats (slated for reclamation) and they have a patina of rust, but remain quite solid. I think it was a requirement, even then, that the catalyst be warranted for 10 years.

A magnet is attracted less to them than to one of the head pipes they're stored with, so I figured it cracked due to being more brittle than mild steel and under some stress. Could it be some of that life in Wisconsin was under the care of someone else?

Maybe the stress is long gone, fixed in a previous repair, but the crack originated then?

Either way, unless you have a warm shop or a good rapport with a muffler shop, you might want to go with the band-aid. This bandage they sell at Walmart. That was a Walmart parking lot where I took the photo, in Michigan. After getting home that fiberglass-based material was like heat-shrunk cement. I know it would have lasted months.

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Art Benstein near Baltimore

Two peanuts walk into a bar, and one was a salted.

thanks for the reply and for checking into your CAT supply. This has a compression donut flange at the front, not sure of the OAL.

Yes I've owned the car 220k of its 310k life. I'll probably go for the bandage covered with a slit coke can and hose clamps and then attack properly in the spring. If however the crack propogates and shears completely through it will be NASCAR very quickly.

I always assembly the whole CAT back w/o clamps tightened, make sure everythign is happy and then tighten. Not sure where stress would come from but suppose its possible.

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'90 245 295k, '93 945 308k

nice illustration!!!!!

Clamp a sleeve over it? you surely could without much trouble

Cut it out and weld in a new piece? that works as well


Replace the CAT? if money is not an issue that works too

if this is just a crack and not rotted as well perhaps just running a mig down the crack might suffice

the only rub i see is the fact the crack is at the joining of two pipes making knowledge of what the condition of the cat pipe that disappears into the muffler pipe unknowable without cutting the bad section out.

you have not stated your skill level and equipment at your disposal so a good suggestion is a guess for now

A picture is worth 1000 words! At this point i doubt that I could remove the muffler from the CAT pipe with out mangling the muffler. I don't have a welder but I have installed probably 6-8 cat-back exhaust systems between my two cars.

I may just have my local muffler shop run a few beads a cross the crack. When it comes time for a new cat-back I'll start swearing then. who know what will happen to the car in the next 2 years. (310k currently) Only problem is that the crack is right across the top of the tube so might be difficult to get a good weld. High quality splice with some muffler paste will probably the next choice if they cant weld. Once a weld is attempted though a splice will no longer be viable becsuse the weld bead will be in the way.

I'll check out the muffler repair bits at the autoparts store tonight.


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'90 245 295k, '93 945 308k

you have one other option that just came to mind.

slice the cat pipe cat side of the crack
slice the muffler pipe just below the point where the cat insert ends

buy a pipe that will fit over both ends and clamp both ends
this may require a bit of pipe stretching but its doable

Is it possible to go to a muffler shop and say: I need a pipe 'X' long with ID 'y' at one end and ID 'z' at the other end?


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'90 245 295k, '93 945 308k

locate a garage in your area that has a pipe bender.

bring or buy from them the pipe you need telling them what inside dimension you require.

most likely they have a pipe that meets one dimension in stock and can EXPAND or contract the other side for you for small money.