Kitchen island drain problem

[Usafexplorer]

I have a newer home on slab construction that is about 7 years old and we have decided to upgrade our countertops. In doing so, my wife decided she wanted to cut down a raised bar portion of our kitchen island. Easy enough, we cut open the wall and found a 2" upside down "U" shaped drain pipe that connected to the sink drain. In order to remove the upper bar top we had to cut the drain down in height. Now the kitchen drain is super slow.

There must be a way to resolve this problem, we just wanted one continuous height countertop on the island. I understand the problem is with the vent, how can I fix this issue? Thanks for any suggestions.

 

[phishfood]

Did you reconnect the two 2" pipes with the upside down U?

 

[Usafexplorer]

Yes, we did reconnect the loop or upside down "U".

 

[Mr_David]

That is the vent and won't drain properly with out it.
Also you have to make sure you don't switch the drain and vent when you reconnect them. Here's a picture.

 

[Usafexplorer]

That is the vent and won't drain properly with out it.
Also you have to make sure you don't switch the drain and vent when you reconnect them. Here's a picture.

I understand it's the vent, and it was reconnected exactly as it was before; we merely shortened the height in order to maintain one continuous countertop all the way across the island.

We also noticed it only affected the disposal side, the other side flows fine.


Update:

I think I discovered my error. The "loop" portion of the upside down "U" is slightly below the horizontal plane of the sink drain; which would explain the venting problem we caused.

 

[lordofthepipes]

nice piture of a island vent Mr david. where did you find it?