The sink in the bathroom has been draining slower and slower until I decided to try using a plunger on it. In doing so I managed make it stop draining altogether.
Today I removed the “P” trap and it looked clear.
The nut on the part of the drain that goes through the wall (a 1-1/2” nipple) was frozen so I had to split it with a chisel to get it off. In doing so I put a couple of good gouges in the threads of the nipple. Once I got the pipe out I could see into the system and could see a ninety degree turn going down. It was plugged with some kind of gunk. I took a screw driver and dug around in the pipe, then stuck the hose of my wet/dry shop-vac in the pipe and sucked all the gunk out of the turn. I don’t have a drain snake but I do have a fish tape (used for pulling wires through conduit) I managed to get the fish tape past the first turn but it stopped at the second I managed to twist the tape around in the pipe. After pulling out the tape I used the shop-vac again and sucked out some more stuff.
The final test was to put a garden hose in the pipe and turn the water on and see if it backs up. We did that and It didn’t back up so now we know that it will drain.
The hardest part was getting the new nut on the wall fitting. Since I messed up the threads it took quite a while to file off the notches and clean up the threads of rust but, eventually I was able to get everything back together, now the sink drains just fine.
Another good day.