What happens to the weld if someone MIG welds aluminum without using Argon of Argon gas mix?
The reason I ask is I have a set of aluminum exhaust manifolds on my boat. On one of them the water jacket cracked, while my son had the boat last winter and let if freeze with a little water in it. He removed it and had it welded. He said the guy used a "wire gun, that fed the aluminum wire as you welded". Questioning him farther made it clear the welder did use a MIG, but my son has no idea if he used gas or what kind of gas he used, if any. He doesn't remember seeing any gas bottles near the welder, and this was done at a home shop, where the guy does welding at night and on weekends.
The weld looks sh*ty. Not smooth and even. It doesn't leak, just looks like armature work.
I don't know if I should trust it, have it removed, and redone or what. I don't want to be 30 or 40 miles out in the Gulf stream and have problems with it, as this is on the main engine. I don't want to have to limp home using the trolling/emergency 40HP outboard, but I don't want to have to stand on my head to remove it from the 454 Chevy engine, which I would just about have to do.