Kitchen Sink / Disposal Issue

[Douglas C Woeckener]

I am at a loss here - Did a little remodel here and replaced the kitchen sink with a stainless farmhouse sink. Went to install the new insinkerator and the drain input in the wall was now too high. I opened up the wall, cut out the t and lowered it about 4 inches. I looked at all the pipes at this point and they seem fine. Put everything back together Connected the air gap and checked for leaks. Here is the fun part of the story. The dish washer drains into that garbage disposal and drains just fine. When running the sink, it drains just fine. If I dump a pot of water or plug the sink the water does not drain. If I turn on the garbage disposal the water shoots back up out of the drain. I took the clean out cap off in the basement and the pipe appeared clean there. I know the vent is there because I moved a small piece from the soffit. It is acting like it is vapor locked when a large amount of water fills the disposal. Why does it work with low amounts of water but immediately clogs when flooded? If there is a blockage, is it possible its in the horizontal line in the basement out to the main line? HELP!

 

[Reach4]

How about a photo of the piping and disposal under the sink.

You may have a partial clog where the drainage turns from vertical to horizontal in/below the basement. Depending on the cleanout in the basement, you may be able to stick a medium Brasscraft drain bladder down there. Otherwise get the drain snaked down from the cleanout with a big-enough snake.