Venting or Blockage...Please help.

Here is a rough picture of how my bathroom is plumbed now.

Attachment 19034

The issue I am having is the toilet is hard to flush. It is slow to flush, and when it does it will blow air back up the toilet. If I take a shower it will slowly blow air up through the toilet. And when the washing machine drains, it will blow a lot of air up through the toilet. Pictured is one of two branches that go out to the main sewer line. The other branch work and drains fine.

One night the entire bathroom wouldn't drain and started backing up into the other branch. Had a plumber come out and run a snake up under the house from an outside cleanout. Cleared the clog and everything ran great. Even the toilet i was having issues with. But 2 days later the toilet started backing up and blowing air again. Yesterday I pulled the toilet and ran 50 ft of snake down into it, reinstalled the toilet and it worked great, flushed normally, didn't blow any air when running the washing machine. But that only lasted a day until it started again.

All this started after we had a flood and I had the contractor move the washing machine drain into the wall. Before it was a 2" pipe running up from the floor thru the ceiling and venting in a whirly bird in the attic. The washer drained into a wye pipe into this drain. When he moved the drain into the wall he never vented it. So on this whole branch the only drain it the 2in at the end of the line.

Ideas? Is there still a partial blockage somewhere in there or do I need to go extreme and install a vent line between the toilet and the main branch?

you have a blockage somewhere or if you are on a septic tank it might be time to have it pumped

ok, i tried sending the snake down the washing drain but i couldn't get it past a bend in there, I'll keep trying.

DIY snakes are seldom effective in clearing a clogged drain. Best advice is to call a plumber with pro equipment and knowledge to clear the problem.

IF your snake fits into the washing machine drain, it will NEVER unplug any stoppage in the main line. Does the vent go THROUGH the roof, or just to an AAV in the attic? You are describing a problem caused by an AAV used for a vent.

On this branch is just terminates in the attic...no AAV (its on the todo list to extend thru the ceiling). The other branch has an AAV in the attic. My snake is a 1/2in 50 footer i picked up from harbor freight. Problem with calling a plumber is I already paid a plumber to do this and after it got stopped up not even a day later he flaked on me 3 times and haven't heard from him since.

A 1/2" snake is "useless" on anything larger than a 2" drain, and I would think that one from Harbor Freight would be even less effective.

Definitely get those vents up through the roof. You can run them horizontally toward each other (just leave a little pitch on them so any condensation/rainwater/etc can drain down), join them into one pipe, and only make one roof penetration. Without knowing all the details of your house, I'm going to recommend a 3" vent through the roof. You might be able to get away with 2" depending on lots of things that I don't know in your situation. Make sure this whole setup is supported, or it will probably sink and throw the pitch off on the horizontals. Use pipe strapping up to the roof rafters.

If you have the ability to get venting to that toilet line especially, but also any other unvented line, that would be highly advisable. It may be adding to whatever problems you're having, though would be unlikely to cause them by itself.