[djwhaley]

I have a double sink, disposal on left, main sink on right, and dishwasher that sits to the right of the sink. If the main sink is full, and I pull the plug, water backsup into the disposal side. IF I run things through the disposal side, water back up into the main sink. When the dish washer runs, water back up into both sinks. We replaced the plumbing last week, and everything seemed to be working great, until I realized one of the clamps was not tightened down and we had a small leak. Tightne th clamp, and back to square one. There is an access pipe in the pasebent that "y"s off the main drain, and we were told to put a little black suction thing on it to regulate the air. Not working the best and at our wits end. Any advice you can give would be great. Can send pictures if necessary.

[speedball1]

You have a blockage. Most likely in the horizontal line in the wall. By

There is an access pipe in the pasebent that "y"s off the main drain

"do you mean cleanout? If so send a snake about 6' into the cleanout. If not then remove the "J" bend from the trap and send your snake into the wall, (see image). You will hit a bend about 8" in but once past that you only have 6 more feet to put out. Flush with a sink full of hot water. Good luck, Tom