[rdcjr]

My sink was stopped up but clears when the dispoasl in run. If the sink is full of water and the washing machine is run it will suck the water out of the sink as the washer empties through a connecting drain.

What could it be?

[speedball1]

My sink was stopped up but clears when the dispoasl in run. If the sink is full of water and the washing machine is run it will suck the water out of the sink as the washer empties through a connecting drain.

what could it be?

The disposal turntable acts like a centrifugal pump so it clears the water under pressure.
I would snake out the washer vent and the kitchen sink vent because one or both of them are blocked. What's happening is the washer discharges and the water draining sets up a vacuum. Since the vent is blocked and can't vent, the system attempts to vent through the sink and the vacuum's pulling out the water. Clear the vents and your problem's solved.
Cheers, Tom

[rdcjr]

Thanks,

So because the vent is clogged there is a vacuum that does not allow water to enter the drain and the sink to drain. That makes sense to me.

This happened overnight, do you think an animal is in the vent or it was closing and just sealed without us noticing the slowdown?

[speedball1]

Thanks,

So because the vent is clogged there is a vacuum that does not allow water to enter the drain and the sink to drain. That makes sense to me.

This happend overnight, do you think an animal is in the vent or it was closing and just sealed without us noticing the slowdown?

It's hard to tell without droping a cable down and snakinh out the line. Regards, Tom