Topic: Gaskets for Catalytic Converter

[Carpe Diem]

Can anyone advise me on the part numbers of each of the gaskets needed when I change out catalytic converters?  I bought a new high-flow cat and want to buy new gaskets.

One person has advised to use high temp copper sealant.  Anyone agree or disagree?

Thanks

[Carbon Sky]

You shouldn't need a gasket on the back end of the downpipe that connects to the catback.  However, you may want to replace the gasket between the turbo and the turbo.  I don't know of any supplier other than GM for that.  I'm sure a vendor like Solo might be able to help.

You shouldn't need to replace the gasket on the back end due to it's design.  If anything, use high temp copper sealant, or even high temp RTV. The gasket looks like some kind of metal braiding with a sealant in it.  Looks reusable to me.  I had to remove my catback to put my "backbone" in, and used some high temp RTV, and have had absolutely no issues for 2+ years now.

[tazz]

The stock Cat to turbo gasket probably will not work on any aftermarket Cat.  The stock gasket is a crushable ring gasket that fits into a ringed groove cut into the stock cat flange and is crushed against the flat turbo flange and seals it.   You probably need to contact Solo to get a flat gasket so you can get a good seal between both smooth mating surfaces.

[cdflint]

I just installed my Solo high flow cat today. I ordered it from Steve.

[Carbon Sky]

The stock Cat to turbo gasket probably will not work on any aftermarket Cat.  The stock gasket is a crushable ring gasket that fits into a ringed groove cut into the stock cat flange and is crushed against the flat turbo flange and seals it.   You probably need to contact Solo to get a flat gasket so you can get a good seal between both smooth mating surfaces.

I have removed my downpipe from my cat 2 times now, and have re-used the gasket both times.  Tightened to specified torque, and have had no leaks.  The last time I re-used this gasket was over a year ago.  If you're dead set on replacing it for safety's sake, go for it, but from my experience, it is not an issue.  I think there's enough "crushability" built into the gasket to make it work.  Put some copper based high temp anti-seize on the turbo studs and worst case scenario, you can always try it out first, and then get a gasket if it doesn't seal.  In fact, put the anti-seize on regardless.  You'll be glad you did the next time you want to remove the downpipe.

[tazz]

HE HAS A AFTERMARKET CAT

If you have the STOCK CAT you can reuse BUT if you have an AFTERMARKET Cat/DP as the OP does THIS DOES NOT WORK VERY WELL.
Problem is with MOST AFTERMARKET setups BOTH Flanges ARE SMOOTH and you will not be able to just place the ring GASKET on the surface without Bonding or adhering it to one of the surfaces.  With the STOCK CAT flange there is a groove cut into the flange to hold the ring in place.
Poor pic of my Catless DP flange.
Unless you temporarily affix the ring gasket somehow the gasket will just drop down. [ Guests cannot view attachments ]

[Carbon Sky]

HE HAS A AFTERMARKET CAT

If you have the STOCK CAT you can reuse BUT if you have an AFTERMARKET Cat/DP as the OP does THIS DOES NOT WORK VERY WELL.
Problem is with MOST AFTERMARKET setups BOTH Flanges ARE SMOOTH and you will not be able to just place the ring GASKET on the surface without Bonding or adhering it to one of the surfaces.  With the STOCK CAT flange there is a groove cut into the flange to hold the ring in place.
Unless you temporarly afix the ring gasket somehow the gasket will just drop down. (Attachment Link)

On my car, it's a stock cat, I have removed and reinstalled it twice.  No issue.  I have done a high flow cat downpipe swap for a local Solstice, and reused the stock gasket, and no issue.

And seriously?!  That's the big problem?  The circumfrential groove put into the gasket is definitely not that deep that it holds itself onto and prevents "dropping down".  And why wouldn't the turbo studs hold up the gasket?

[tazz]

Yup it is, the ring gasket fits snugly into the groove on my STOCK CAT so it doesn't move or fall during installation.  Just measured the smashed height of a old ring gasket with my calipers and it's 1/8" so the groove is approx 1/8"deep.
Not saying he can't do it a different way just a bit more difficult and a possibility of misalignment of gasket.  Solo can have the right gasket to him in 3 days for $20 with no possible issues.  I have no problem spending a measly $20 for perfect fitment but to each his own I guess.

[Carbon Sky]

Yup it is, the ring gasket fits snugly into the groove on my STOCK CAT so it doesn't move or fall during installation.
Not saying he can't do it a different way just a bit more difficult and a possibility of misalignment of gasket.  Solo can have the right gasket to him in 3 days for $20 with no possible issues.  I have no problem spending a measly $20 for perfect fitment but to each his own I guess.

I could see an argument for sealing issues.  Crush type gaskets typically have only so many crushes in them before leaking issues can become a problem.  But to be honest, in over a decade of a lot of working on cars from tearing out entire engine/transmission combos, rebuilding engines, rebuilding transmissions (way harder than engines in my opinion), all non-warranty work on multiple cars in the family, and when it comes to crush washers, in manifolds, exhausts, drain plugs, etc, I've found that because the crushing gasket is that malleable, it tends to be able to seal repeatedly, even when manufacturer recommends one time use only.  I've done this with aluminum washers, copper washers, steel alloys, etc, and honestly, unless it's a known platform issue for having sealing difficulties to begin with, reusing is typically not an issue.  At least not once or twice. 

Here are more people with similar experiences that have reused, with an aftermarket downpipe, and have not had issues

http://www.cobaltss.net/forums/2-0l-lnf-performance-tech-153/gaskets-downpipe-267903/

And I didn't say he definitely should not get another gasket.  I merely suggested that he try re-using the original gasket first.  Be sure to use high temp copper based anti-seize on the studs to make removal easier in the future.  And should he have a leak, then go back in with a new gasket.  Because honestly, I don't think he'll have a problem.

Who knows, maybe I've got an unreasonable expectation of how much work people are willing to do themselves.  For me, removing a downpipe is not a big deal.  So trying the original gasket first isn't a big deal, if I do have to go back in again with a new gasket.

[Arabas]

contact spicy. he can send u one. don't use sealant.

[cdflint]

I should have said I have a Solo HF cat and I ordered just their metal gasket for the spot in between the turbo and the cat. No gasket needed from the cat to exhaust pipe. It was not expensive. Contact Spicy/Steve, he'll make sure you are set up right.

[Readheaded RedLine]

I am having a similar problem.  We have blown out the gasket between the exhaust manifold & turbo 4 times in 9 moths.  Once, both the turbo and manifold had cracked.  The other times the bolts just backed out.  GM isn’t warranting any more.  Does anyone have a more permanent solution (mo-betta gaskets?) other than buying gaskets buy the six-pack? -M

[1LILNDN]

Mine was installed and just the Turbo to Cat Gasket was needed from Solo . The Exhaust ring flange bolted right up tight. with no Leaks.