Welding on SS Exhaust ??

[NWOhioChevyGuy]

OK, my wife drives a 2012 Cadillac SRX and it has an bellows on the front pipe that has failed, or very soon to be.
I have had one other part on this assembly welded by a local service shop and it has held up fine for the few years it has been on there.

I have a 120V Lincoln MIG welder and it can have the polarity changed to use a Stainless wire. I have some Blue Demon 309LFC-O here that I wanted to give a try.
Am I up for a fight to get this welded up or will it go as I expect? The pipe for and aft the bellows is in great shape.

Plan is to cut out old bellows and tack the new one in place while pipes are on the vehicle then remove for full welding.
I would buy a new pipe, but they are CRAZY expensive as it includes the front cat, a Y, two flanges and 2 vibration thing-a-ma-bobs.

I have invested $50 at this point in components I need to weld it up, so I am going to give it a try.

 

[toddoky]

If you’re attempting a repair with a long term durability, it’s hard to say 309L is the best choice without knowing the exact material of the tubing and bellows you are welding. It’s quite possible one or both of them are some 400 series of ferritic stainless (409, 439 etc.). They could also be 304SS, or an aluminized stainless material. Have you checked to see if a magnet will stick to the pieces being welded?

 

[NWOhioChevyGuy]

The exhaust is a 400 series of some sort as a magnet sticks.

The bellows are only available in 304 so that is what I have.

 

[toddoky]

I think the 309L is a suitable choice, but I’ve never welded stainless steel with flux core wire, so I have no idea how that in itself will affect the outcome. You already own the wire, so you don’t have much to loose by giving it a shot.

 

[dogdog]

309L for different stainless types 300 series-400 series etc... I thought TRI-gas was needed not sure about flux cored 309L stuff

308 for 304 stainless

I think you can try ER-CUSI-A to get some colorful looks also, not sure what gas for mig wires...

I have used regular mig wires on some portions that the gap was too big for the tig wires that I have, and it's been holding up fine.

There was another thread earlier (2018 or 2019) some one with the same/similar question, he ended up just mig the whole thing "supposedly"... All I remember is he's Canadian.

 

[NWOhioChevyGuy]

The wire I have is a flux core from Blue Demon.

 

[Wrench97]

I always use nitrogen or Trigas both inside and outside the pipes.
Flux core is going to be ugly and probably too hot and cause cracks.

 

[DanarchyCustoms]

Go for it. It never hurts to try it.
You will receive a million different answers here but fix the car and get it back on the road, after all it is just an exhaust.

I use 309L-AP Select Arc with 100% CO2 to weld SS to regular steel. Never used this on exhaust but the stuff welds great.

 

[dogdog]

Don't forget about back purge. if you are doing stainless...

Nitrogen or SolarFlux.

 

[Modern Garage]

Don't care if I get flamed or not, I've done a bunch of these on GM cars and I just grind the cracked flex off and MIG the new one on. No TIG, no stainless wire, no gas purge... It's a car, not a space shuttle. Could it rust off? Not likely, given its location. But the factory used a higher alloy... Yup, and it failed in short order, that's why it's here.
Thats what works. It's your car, do what you want.
Joe

 

[NWOhioChevyGuy]

Don't care if I get flamed or not, I've done a bunch of these on GM cars and I just grind the cracked flex off and MIG the new one on. No TIG, no stainless wire, no gas purge... It's a car, not a space shuttle. Could it rust off? Not likely, given its location. But the factory used a higher alloy... Yup, and it failed in short order, that's why it's here.
Thats what works. It's your car, do what you want.
Joe

I half expect that is what the shop did on the first repair.
I don’t care if it is pretty, it just has to work.

 

[laser3kw]

I agree with modern garage ^^^^^
I cut and welded my SS cat back to fit my truck. Welded it with regular S7 mig wire. It held without fail for over 10 years. I ended up trading the truck, weld still solid. Granted, the weld was in a "cooler" area, but also, it was right in front of the left rear tire, seeing all the Illinois winter snow / salt abuse.
Fast forward to this month, my local, trusted, mechanic just replaced our flex joint. He did the same method: cut old joint out, weld new joint in. He also uses regular S7 mig wire, always has. He says when a car is old enough to need a flex joint, the weld will out last the remaining life of the car.

 

[dogdog]

It all dependents on the OP's intention if he is to go for looks or just make it work.

if it is only a 120V mig welder he has, make sure you get the smallest size flux core or mig wire... I know the .035 I used burns through a lot of aluminized steel many of the times especially on butted joints... If he is doing expanded joints.. then he would be ok.. the point... get smaller wires especially if you have 120V machines.

 

[NWOhioChevyGuy]

It's an 120V 0.035 machine / setup.

Worst case if I cant get it welded up then I find someone to TIG it after I tack the assembly together.

NOT going for looks in any way shape or form. It's a 10 year old daily driver not a show car.

 

[dogdog]

Try review some of the youtube videos on "mig like tig" I have used that to help on the burn through if you do encounter that... might come in handy. just go over few times to make sure you don't have pin hole leaks. I switch to .030 flux core (smallest flux core wires availiable) now on my lincoln SP135T smaller mig when I needed to run flux core and when gas is expensive. It worked out pretty good..

 

[NWOhioChevyGuy]

Doing some thinking and with the shape and size of the pipe, purging is not likely going to happen.

Would doing the Solar Flux trick help?

Pardon Our Interruption...

If it goes together as I expect the existing exhaust pipe should slide into the machined end of the new Bellows so it will not be a "****" joint.
This is the bellows I purchased.

FAPO 2" ID ULTRA STRONG EXHAUST FLEX BELLOWS 2.55" Long Flex Joint Pipe T304 SS | eBay

Inner Smooth Pipe, Compact shape, Robust Design. -The double-deck design, with a Reinforced wall, ULTRA STRONG. -Universal, For Exhaust System, Downpipe, etc. -The accessories in the photos are included.

www.ebay.com

 

[dogdog]

you might not need those solar flux, it's nothing but back purge or flux to protect the back side of the stainless metal where shielding gas/gases could not, that is only when you get the stainless heated way up to that critical temp when it started to "sugaring" oxidation and lose its characteristic... lots of people choose not to do it as well on their fixes, I think that subject have been beaten to death... you should be fine if you don't over heat it. Just a suggestion since you mention "stainless welds" It's something you should be aware of.

How to Solve 10 Common TIG Welding Problems [Guide] | MillerWelds

This visual guide will help you learn about 10 common TIG welding mistakes as well as basic tips on how to prevent these errors.

www.millerwelds.com

holly snit, that price got up there 2x, I bought that 1LB can for $30 back then, now 150% increased.

 

[steel 35]

Similar threads;
Brought this back is it done yet?
Here is the only thing that can possibly fix this problem!
If your interested please ask for a quote, I will be posting these items on Craigslist and Ebay, so please expect pricing accordingly

 

[NWOhioChevyGuy]

No have not got to this project yet, plate is too full with other things at the moment.
I do not have a TIG machine, will be attempting this repair with a MIG.

If things don’t go smoothly, I will tack it and take it somewhere to get it TIG welded.

 

[engineer2]

Our local budget muffler shop MIG welds stainless exhaust. The repair lasts about 2 years in our rust belt climate.

 

[steel 35]

Our local budget muffler shop MIG welds stainless exhaust. The repair lasts about 2 years in our rust belt climate.

I do too, the 309 doesn’t tig at all like the good stuff.

 

[theoldwizard1]

OEM stainless exhaust are some weird alloy. Something you can not buy anywhere. Not sure if it affects welding.

 

[dogdog]

There is always the lower temp ERCUSI-A sil-braz might wires you can use... lower temp, and argon gas mig or tig.

 

[Willie Makeit]

OEM stainless exhaust are some weird alloy ...

lol ... no it's not