2 sinks gurgling when any water drains (other sinks don't)

[NForeman]

Hello all.

Strange issue here. I have two sinks, an upstairs bathroom sink and my first floor kitchen sink, that seem to have a slight gurgle once they drain. This can happen if the sinks are full and drained or have running water from the faucet running in to them. And it happens if it's just a little faucet flow and then stopped or the faucet is on full and then stopped.

The strange thing is this: it's only these 2 sinks out of the 6 in the house. Heck, the bathroom sink has a companion sink on the left and it doesn't make a noise at all. They are not on the same initial piece of PCV pipe: they join the main drainage line about 20 feet apart and each has other non-gurgling things on that joint (toilets, showers, etc).

Any ideas on how I can go about troubleshooting this? I've been under the house and don't hear any obstruction in the PVC (had a backup a few months ago that I snaked and could hear the difference, this is not that). I have also tried some drain cleaner, though it was just some Roto-Rooter stuff that is mainly a grease specific preventative (left over from an old blockage visit).

Thanks!

 

[frodo]

are they above each other?

you may have a blocked vent if they are revented together

 

[ExtraMilePlumbing]

Cable the bottom sink with a 3/8 cable

 

[NForeman]

are they above each other?

you may have a blocked vent if they are revented together

Nope. The sinks that connect above the kitchen sink (the master bedroom sinks) don't gurgle at all. And the sink below the bathroom sink that gurgles, and the one beside it in the same bathroom, also do not gurgle.

 

[NForeman]

I have noticed this vent on the kitchen sink. Could this be clogged and making the kitchen gurgle? How would I even clean this out?

Still no ideas for the upstairs sink though.

 

[Matt30]

The air admittance valve could have failed. Replace it and extend it so it is above flood level rim of the sink

 

[NForeman]

Lol, here's some fun.

I tried to remove the old trap by twisting it. Apparently the prior owner of the home tried to do the same thing and when it broke off for them they just set it back up there :/

So now I have to cut the PVC and attach a new vent.

And I assume it was never a vent problem because this one was letting air in and out if it was just setting atop the pipe.

Also, while I was under I heard that it was the P-Trap itself that is gurgling. That's what's to be expected, right (all gurgles are from that water moving)?

is there any sense to just detaching the P-Trap and cleaning it out just in case it's something in there? The drain isn't slow at all so I had not even considered it.

 

[NForeman]

The air admittance valve could have failed. Replace it and extend it so it is above flood level rim of the sink

Sorry, I don't quite understand that. What is the flood level rim of the sink? Is that higher than under the sink itself? if so I have no idea where that could even happen.

 

[NForeman]

Ahh, ok. Googled what you said. I still don't know how I could even do that in its location.

And I am pretty sure we have a whole house vent to the room, but I have no way to go up there and check it. Might have to call someone in for that if it got clogged or something. Still strange it's only 2 sinks out of 5 sinks, 3 toilets, a shower and a bath. And they aren't on the same vertical pipe segments.

 

[Matt30]

You don't have to get it in the wall....just get it up under the counter top

 

[NForeman]

You don't have to get it in the wall....just get it up under the counter top

Brilliant, thank you. I forgot that part of the sink area does go above it and I believe it may be hollow.

Another question: my main vent to the house would not be blocked if there are no slow drains, right? Really want to avoid a roof visit.

I have had 2 blockages in the main line out of the house in 2 years, but I always just snaked those and then the way was completely clear (clean flow before and after the block). Hoping it's not somehow related.

Thanks for the help, I really appreciate it.

EDIT: Nope, I can't get it above the flood level. So this will not be to code if I fix it and I guess it never was. No idea what to do now. I could cap it off since I have a main house vent I guess, but is that just inviting trouble?

 

[NForeman]

Sorry for all the posts, just trying to provide as many data points as I can.

I placed some seranwrap over the open pipe and rubber-banded it in place. I then ran some water in the sink. When I did, the seranwrap did not so much as wiggle, so I can't imagine that any air is actually trying to be pulled from that spot. What an odd thing to be there if it isn't doing anything.

EDIT: Ok, flushing toilets makes it wiggle a little., but nothing that makes it seems like a ton of air is being pulled.