Replacing Cat back with Dynomax and broke the 2 cat bolts

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Foos

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94 K1500 5.7 ext cab
I bought the dynomax
17380
SINGLE - 3" CAT-BACK SYSTEM - SUPER TURBO™ MUFFLER

Taking the old exhaust off today and both cat bolts broke, are the remnant bolts that are attached to the cat removable? My hammer didn't budge them.
Also, there doesn't seem to be a donut between the cat and the old exhaust pipe, should there be? it didn't come in the dynomax kit.
thanks
 

Schurkey

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both cat bolts broke, are the remnant bolts that are attached to the cat removable? My hammer didn't budge them.
I'd expect two through-bolts, nuts and lock-washers on the back side. Shanks should pound out unless you bent them twisting 'em off. Minneapolis tinworm will not help this procedure; and don't hit the bolts so hard that you bust-up the monolithic cat (assuming you have a monolithic cat and not pellet-style.)

Also, there doesn't seem to be a donut between the cat and the old exhaust pipe, should there be? it didn't come in the dynomax kit.
thanks
I'd expect a gasket not a donut.

POST PHOTOS, nicely cropped, sized appropriately, and in-focus.
 

Dirty Bird

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94 K1500 5.7 ext cab
I bought the dynomax
17380
SINGLE - 3" CAT-BACK SYSTEM - SUPER TURBO™ MUFFLER

Taking the old exhaust off today and both cat bolts broke, are the remnant bolts that are attached to the cat removable? My hammer didn't budge them.
Also, there doesn't seem to be a donut between the cat and the old exhaust pipe, should there be? it didn't come in the dynomax kit.
thanks
Just did mine few days ago broke all three. Tried drilling them out went to several drill bits. Went to Home Depot bought a bottle of MAPP gas and heated it up and popped them out with a punch. Found a 6 stud/6 nut kit at roc auto. Worked perfectly.
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78Monte

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I put the same setup on mine a month ago, I let the bolts soak in pb blaster a coupe days prior and they came off fine..

Mine did not have a gasket or donut on the stock setup and the replacement exhaust didn't come with it either. when you bolt it together it will seal assuming the rest of your exhaust is stock..
 

Schurkey

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Just did mine few days ago broke all three.
Common. They run hot, and get lots of road-splash. Guaranteed to corrode.

Tried drilling them out went to several drill bits.
As you found out, that's a tough job with little chance of success.

Went to Home Depot bought a bottle of MAPP gas
No, you didn't. Real MAPP gas has been out-of-production for over a decade. You bought a yellow bottle of MAP-Pro, which is deceptively sold as if it were MAPP, but it isn't. It's only slightly hotter than propane. Mostly a waste of time. If this country had a functioning Federal Trade Commission, (FTC) the sellers of MAP-Pro would face fines and other penalties for deceptive trade practices.

Oxy-Acetylene, or one of the new "inductive" heating elements is the better way to do this. I'm thinking that when my fasteners broke on my '97, I smacked the broken pieces out without heat--but I don't remember for sure.

OTOH, it's hard to argue with success--and you got the job done.

and heated it up and popped them out with a punch. Found a 6 stud/6 nut kit at roc auto. Worked perfectly.
I just installed generic bolts 'n' nuts, with some washers here and there. Stuff I had lying around the shop.


Mine did not have a gasket or donut on the stock setup and the replacement exhaust didn't come with it either. when you bolt it together it will seal assuming the rest of your exhaust is stock..
The gasket (at least for my vehicle) is this one:
https://www.napaonline.com/en/p/EXT31618?

The flanges on the pipes were warped, and the gasket didn't seal very well. Tried to seal it with Liquid Miracle, That helped, but didn't completely stop the leak.

https://www.amazon.com/Permatex-803...Permatex+exhaust+sealer&qid=1603828472&sr=8-1
 

Foos

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I started this thread and I ended up going to a independent muffler shop and they used a Oxy-Acetylene torch, heated them up red hot and knocked them out with a hammer. It took the guy 2 minutes tops, I paid him $20 and it was worth it. The dynomax system works fine and for the $125 I paid (after rebate) it was well worth the price.
 
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