Welding Muffler

[Dave F]

Skypirate is correct.

Your have to back purge with argon to get rid of the oxegen. Porosity nad cracking with happen otherwise especially on used SS material.

Best advice is take to a knowledgable Tig Welder and if he does not think back purging is important then he either does not know or wants to to come back for more money when it cracks again.

[Dave F]

You can still weld stainless with regular 70s-6 wire through a mig. I did it for my exhaust and just painted the welds with high temp paint. You can see the black paint on my exhaust joints in the pic near the firewall.

70s wire is the wrong wire to use on SS

with SS alloys 304L- 316L your enemies is carbon and Manganese.
You will definalety be more prone to cracking with higher manganese levels in your wire. Mig can work with ss wire like 308 but on thin wall SS you will have alot less control

70s is as mild steel wire and great for carbon steel..


Hope this helps to rectify.

[Geowitz]

I think we all know(or could find out pretty easily) 70s6 is a mild steel wire... Yes, for the "know it alls" it isn't correct, but it does work and is an option. My intention was to explain that if he needed a quick fix on the cheap was that he could do it with mild steel wire as it sounded like he was trying to do it himself and gave up. It's done all the time and whether you get cracking can really go either way and has more to do with mounting and vibration than dissimilar metals. I did it with my exhaust and it's working fine. Just letting him know it's an option.

Hope this helps to rectify.

[Dave F]

Quick fix yes - but will not last.

Cheaper to do it correctly the first time than have to clean off the failed weld area again and remove the mild steel wire.

I have been welding for over 40 years and work in the steel business now and work with over 300 alloys for repair and re-manufacture as well as casting.

We do not weld $500 or $100,000.00 castings with the wrong materials or procedures as failure is not an option.

This should help rectify any confusion that any might have.

[Geowitz]

Never mind. Not worth it.

Pete - Sounds like whatever you do you may still have problems because of the design. Maybe investigate bracing your tailpipe or addressing vibration sources like Steves142 mentioned.

[Peteohms]

The muffler lasted 20 years. Not bad. I'll be taking it to a well respected welder
who was just recommended by an A&P friend.

I appreciate all the comments.

[turboturner]

Am not a weld expert but the chap who repaired mine the last time added a 3rd support brace from the edge of the muffler to the exhaust pipe. That was 2 years ago - no cracks since (50 hrs). As someone else mentioned in this thread, additional, all-round support is the answer, IMO.