I drilled a 7/16" hole in my y-pipe, and welded on a nut, for an O2 sensor. Once I put the exhaust back on the car, the spot just happened to be ~1" away from the SFC's, so i'm going to have to patch it, and redrill.
Assuming I can successfully use my angle grinder to remove the nut, and reweld it elsewhere, and drill the hole again -> What can I use to patch a 7/16" hole? I have a little stick welder, which I don't think is particularly easy to use to fill holes. Muffler cement? Put a patch on it and weld it?

Thanks

 

A piece of exhaust pipe, cut to slightly larger than the hole, welded around to seal it to the header pipe.

 

best bet would be to put a bolt in there with the proper sized threads and some never seize on the threads of the bolt and call it a day.

 

hmm, that would be easiest xpndble, but I'd need a super short M18 bolt for that, I have almost no room in front of the nut, hence why I can't use it for an O2 sensor...

I'll try and find a short piece of 3" exhaust pipe, and make it into a band aid then. Maybe I can find a new M18 nut while i'm there too.
thanks

 

jegs or summit sell 02 sensor plugs or maybe your local parts store.

 

Might not work/be the kind of fix you want, but I just recently fixed my little beater Escorts exhaust with a soup can with the top and bottom cut off, and cut down the side. I put that over the leak, hose clamp it, and no more exhaust leak. I've fixed a few holes in exhaust systems that way. It looks crappy, but it functions just fine.