Kitchen sink virtually clogged need help any ideas?

I bought a place(2 story townhouse with basement) that was built in the 70's a few months back and just a couple of months ago started having problems with the kitchen sink.

The Situation:
I have a small kitchen and there is only one sink with a garbage disposal attached below it. Basically it is "virtually" clogged as the water backs up when I turn on the faucet or operate the dish washer but... as soon as I turn on the garbage disposal it forces the water down the sink and then there is always some "back flow" (some water comes back up) as I turn the garbage disposal off.

Things I have Tried:
1. cleaning the "trap" under the sink (i found nothing in it)
2. using a plunger
3. using "Instant Power Drain Opener" (home depot guy recommended it and said to run 2 cups of water right afterward i used the chemical since i was pouring it into a sink with a garbage disposal)

Anyways... nothing has worked yet ... so i'm debating buying a snake or checking the roof for a vent (i'm not sure i have one) or just calling the plumber...

any suggestions???

Thanks,

Gary

Shine a light down into the disposer. It might be time to replace it. It would be nice to bypass the disposer and pour water down the drain and see if it still happens.

kingsotall said:

Shine a light down into the disposer. It might be time to replace it. It would be nice to bypass the disposer and pour water down the drain and see if it still happens.

Click to expand...

perhaps ... although so another point i should include is that when i took some pipes apart under my sink to try to clean out the trap... i ran water down the sink, past the garbage disposal and into a pan ... so i'm not sure that is the issue since it didn't clog

Well then that tells you the clog is further down than you can reach.
You need a plumber to clean the drain!