Speedball1 would use a gallon of bleach. I use a 50/50 mix of table salt and baking soda followed by a cup of vinegar. However, if you can rod nothing bets rodding

I agree with Bob ½ a cup of baking soda ½ a cup of table salt mixed put it in the drain and put 1 cup of vinegar leave it over night put a pan of boiling water in the morning and the drain will be clear, Thanks.

John

A snake has not worked; the clog must be past the point where the two drains connect inside the wall. Boiling water alone did nothing (other than prove that the line between the two sinks is clear, since pouring it into one sink brought it up to the same level in the other). I will try the soda/salt/vinegar next.

Yes give it a try, Thanks.

John

No go. I let the baking soda/salt/vinegar solution sit over night. It sure bubbled for a long time. This morning I poured in a pot of boiling water, and it just filled up the sink and is sitting there.

When you used the sanke how far did you go, follow BallengerB1 (Bob) suggestion in post #18 remove the traps and use the snake, Thanks.

John

Removed the traps. The snake ran in one trap and out the other without hitting any obstructions. The clog must be below where they connect, back inside the wall someplace, but above where the tub and toilet join, since those work correctly.

You need to go inside the wall you have blockage further down, Thanks.

John

Methinks it's time for a pro, then. Thanks for all the advice though. I got 3 out of 4 problems solved for the cost of one new flapper, so I'm ahead.

Thanks for the heads up, please let us know when the job is done, good luck.

John