My 60 year old house has 4" copper sewer pipe in brass fittings. Both sides of a 10" section below a brass T going to the upper floor toilets have holes corroded into the copper pipe. The best I can tell, the rest of the system is solid. I have temporarily stopped the leak by coating a sheet of light-weight aluminum with a thick layer of silicon sealant and wrapping it around the pipe.

Is there an easy way to do a permanent repair short of sweat soldering a new piece of 4" copper pipe. That would need to be handled by a professional and would undoubtedly be quite expensive.

I have other issues with the existing drainage system and I may elect to replace everything down to the cast iron floor clean out flange, if a repair of the leak is too difficult or expensive.

 

You could cut the sections out and replace them with PVC attached with 2 Fernco's.

 

Agreed, ferncos or mission coupler to convert to a PVC pipe will set you back $10 or $20, and you can do it in probably half an hour.

I like Mission couplers (ones with a metal band and the two hose clamps) better than Ferncos, but it really shouldn't matter much either way.

While you're at it, you can replace as much as needed.