[Jimmer]

Bear,

When you say your 'sink vent' is overflowing... do you mean water comes up into your sink bowl when your dishwasher is draining or do you have pipe/vent somewhere else that you are referring to?

If you you have a two bowl sink and the water is coming up in the first one (with the disposal and dishwasher connected below it) then you have a blockage on the drain side of the disposal. If it backs up into both sink bowls then the blockage is in the p-trap or downstream from that.

If you have further info, or I misunderstood you problem please let us know.

Good luck, Jim

'Just a handyman trying to help'