[Nils]

Have gotten a couple calls now to weld up broken muffler pipes. Both were geographically undesirable so I didn't get into it. Frankly, I've never actually welded used muffler pipe. Seems too dirty to TIG unless I spent extensive time cleaning metal inside and out. I know the muffler shops routinely use Oxy/Acet to do this. Anybody got any insight on this? Any pros out there on this type of work?

[AFSATCOM]

I tried reusing some old pipe on a friends truck. It was so thin from corrosion, the MIG just blew it apart. Went to O'Reilly's and got some new pipe sections to put in, cut back to where it was thick enough and it was cake at that point. Probably won't be clean enough for TIG though.

[Alexa]

Nils.

Welding corroded muffler pipes does not seem feasible.

To get through a pinch, until replacing the pipe, patching the hole with some sheet metal, then fastened by clamping with wire or metal straps.

I have never used them, but there are putties and foil wraps that are used to seal up the corroded areas.

Not a lot of help this time around.

Alexa

[WerkSpace]

Old exhaust pipe gets tempered and will often crack along side your repair weld.
It's best to salvage good exhaust pipe from a scrap yard, then make the repair with a better quality pipe.
I use a SawZall to cut it, and I weld it with oxy-acetylene. (Automotive exhausts can get expensive.)
I don't even look at the make and model anymore, just measure the diameter of the pipe and go hunting.
You will also need to purchase some tail pipe expanders, so that one pipe fits over the other.

[CraigLam]

I just finished replacing a muffler on a friends old '87 Cutlass. I used .120. You could use .060, but it's really thin. I mig'd it on about B or C setting with a feed of about 1.5 to 2. You have to work fast 'cause you'll blow a hole thru the pipe. I used a sleeve instead of an expander. Either way is fine, I guess. With a sleeve, you can grind off the pipe side without destroying the muffler. I made my own hangers. Since I have my own bender, I was able to make the parts myself. I didn't have to pay or run back and forth to the muffler shop.
Werkspace has the best idea. Hunt for scrap!

[allen6634]

Have gotten a couple calls now to weld up broken muffler pipes. Both were geographically undesirable so I didn't get into it. Frankly, I've never actually welded used muffler pipe. Seems too dirty to TIG unless I spent extensive time cleaning metal inside and out. I know the muffler shops routinely use Oxy/Acet to do this. Anybody got any insight on this? Any pros out there on this type of work?

i have done my own exhust work ,( mainly i like to save money on labor if i can do it) i go to the muffler shop buy a new straight pipe , whene i get under my car i find the best looking place to make my connection. if i am just trying to fix i will find a with a big enuff i. d. so i can run the old stuff in the new , when i weld it all back , i keep my heat low and on the new as much as i can. this is a repair i have only done for my self, wat to much work.

[5DIMES]

Ive used "used" exhaust pipe many times, always MIG welded. you can almost always get it for free from car dealerships if you just ask. Ive worked in dealerships where we were replacing exhaust under warranty for some of the dumbest reasons. mid 80s mustang had SS and it was corroding around the tip, so they got new pipe from the from the converter back. It made great "custom exhaust" for what ever you wanted. The Ratrod sitting in my shop right now has pipe from my buddys Roadrunner on it, it wasn't bad so it went on my truck. and looks way better than shiny new pipe on a flat black and rusted truck.