I'm missing the part where you say, "he attempted to snake the drain, but wasn't able to". My point being, how does he know how the pipes are configured if they are behind the wall?

Look, I've seen some really funky stuff on 80 yo plumbing... but if the drain was working and now isn't, if I were the plumber I'd pull apart the trap (plan on replacing it) and clean out all the gunk in the tailpiece and as far as I could snake into the wall. That's usually where the clog is. The next area that gets clogged is in gal pipes that just get caked with crud and corrosion. In that situation, you may need to replace pipes.

For about $200 you can buy a power rooter at the big box store. Snaking a line only leaves a small hole in the clog and will plug again. Running a power rooter that scoures the sides of the pipe will keep it clean far longer. My vote is for Roto-Rooter or a similar company in your area.

Thanks much for the advice - I know zero about plumbing and your insights really help. I'm going for a second opinion.

The Plumber is correct.

The post clearly states the house is 80yrs old and no doubt the line in question is original to the house, therefore we can be assured that the DWV system pre-dates ABS or PVC piping.

In those days lines 2" or greater were generally cast iron pipe, while 1-1/4" and 1-1/2" branch lines were galvanized iron pipe, copper pipe or possibly lead pipe.

The did not have DWV grade fittings for galvanized iron pipe or copper pipe, therefore the bends were made with pressure type fittings, which have a sharp angle rather than the curved radius angles common to DWV fitting. Regardless of what kind of tool you use, when rodding those type of lines you can only go to the first 90deg bend, but the snake cannot make the sharp 90deg bend of the pressure fittings.

The immediate solution would then be to open the wall at the offending joint, cut the pipe and snake the remaining portion of the line, then reconnect the pipes using PVC or ABS with a sanitary elbow and Fernco's, however you must keep in mind that the same problem can occur at the next angle fitting on that line.

Given that you will have to open the wall anyway, the permanent solution would be to replace all the concealed pipe with ABS or PVC.

I'd have to basically agree with Jake. Even though it's a sink, there's a good chance it's a hair clog that's not too far away. You can remove the trap and use a hand auger as far as you can reach (which probably won't be too far).

Regarding those tight bends, maybe I've just been lucky, but I've pushed and turned my 1/4" auger through what was probably some of those bends. I use one with the smallest/tightest head I could find, using simultaneous pressure and turning.

A second opinion is a good call.