Clogged Sink Drain

[crokett™]

the master bath has double lavatories.  Call them Sink 1 and Sink 2.  They both are on Studor vents.   On each sink the drain goes down through the floor of the cabinet and not back into the wall after the trap.  Sink 2 the drain is slow.  If I remove the studor vent, it is not slow.  Replacing the vent did not make a difference. Even with a new vent on it is slow. I have snaked from the top with a drain cleanig tool, down through the vent under the counter and in the cleanout just above the bottom of the cabinet.  The tool comes out clean.  Sink 1 is not slow, but when it runs for long enough air bubbles up through the trap of Sink 2 and comes out the drain in the bottom of the sink.   So where would the clog be? The toilet and shower both drain just fine.

[Snipe Hunter]

the master bath has double lavatories.  Call them Sink 1 and Sink 2.  They both are on Studor vents.   On each sink the drain goes down through the floor of the cabinet and not back into the wall after the trap.  Sink 2 the drain is slow.  If I remove the studor vent, it is not slow.  Replacing the vent did not make a difference. Even with a new vent on it is slow. I have snaked from the top with a drain cleanig tool, down through the vent under the counter and in the cleanout just above the bottom of the cabinet.  The tool comes out clean.  Sink 1 is not slow, but when it runs for long enough air bubbles up through the trap of Sink 2 and comes out the drain in the bottom of the sink.   So where would the clog be?  The toilet and shower both drain just fine.

Are the stoppers open enough to let air in? How to they do without the stopper in?

[crokett™]

Are the stoppers open enough to let air in? How to they do without the stopper in?

Without the stopper in same thing behavior.  The stoppers are ones that you push down on the stopper to close them, then push again and they pop back up.  However, they are open enough to let air in.

[Roly]

Without the stopper in same thing behavior.  The stoppers are ones that you push down on the stopper to close them, then push again and they pop back up.  However, they are open enough to let air in.

The drain is clogged somewhere past where both vanity drains tap into the main line before the stack vent.   The problem is the main takes a while to fill up and the air cannot get out as water goes in since the bubbles and back up.   Taking the Studer vent out allows the air out that is being compressed which allows more water to go in.   Put the snake in the cleanout and make sure it goes in the correct direction in the main towards the stack.  Roly

[crokett™]

The drain is clogged somewhere past where both vanity drains tap into the main line before the stack vent.   The problem is the main takes a while to fill up and the air cannot get out as water goes in since the bubbles and back up.   Taking the Studer vent out allows the air out that is being compressed which allows more water to go in.   Put the snake in the cleanout and make sure it goes in the correct direction in the main towards the stack.  Roly

I was wondering about that but was trying to wrap my head around the venting issue.  In theory the studor vents vent the sinks,   Unless it's that the clog is preventing the air from getting pushed ahead of the water to the main stack?  to be clear not doubting you just seeking to understand.  I will snake the drain at the cleanout.  hopefully I don;t have to get under the house, this bathroom is at the opposite end of the house from the crawlspace entrance, so I am crawling 70' over/under/around every other pipe, HVAC vent, etc that there is.

[Roly]

I was wondering about that but was trying to wrap my head around the venting issue.  In theory the studor vents vent the sinks,   Unless it's that the clog is preventing the air from getting pushed ahead of the water to the main stack?  to be clear not doubting you just seeking to understand.  I will snake the drain at the cleanout.  hopefully I don;t have to get under the house, this bathroom is at the opposite end of the house from the crawlspace entrance, so I am crawling 70' over/under/around every other pipe, HVAC vent, etc that there is.

Studer vents only let air in not out so if you fill up a clogged pipe the air must come out to as it is filling up.  If I have it right the bubbles coming up the drain iis that.   Try running the snake down the cleanout on each drain and towards the main stack.   Try to make sure the snake does not go back to the other cleanout.  A little harder if you can not see how the drains are laid out. Roly

[crokett™]

Studer vents only let air in not out so if you fill up a clogged pipe the air must come out to as it is filling up.  If I have it right the bubbles coming up the drain iis that.   Try running the snake down the cleanout on each drain and towards the main stack.   Try to make sure the snake does not go back to the other cleanout.  A little harder if you can not see how the drains are laid out. Roly

Forgot to update, I cleared the drain Saturday.  it took more time to find my snake than it did to clear the drain.  Sink 2 had the clog.   I didn't tell her this but that's the sink my wife uses...

[crokett™]

I am pretty sure that sink 2 is closest to the main stack, based on where the sinks are in relation to the shower and toilet, but I could be wrong. Also sink 2 is the one that bubbles when sink 1 is being used, so that implies the water is moving from sink 1 to sink 2. sink 1 doesn't bubble when sink 2 is used, sink 2 just backs up.