Gurgling Bathroom Sink

[AlGreen]

A leak from one of those areas causing mold, mildew, etc. was my first suspicion, but I can see the wall cavity and under the tub pretty well and there's no sign of moisture. Also, the grout around the tub seems fine. That said, there are signs that moisture was present in the past, including to one side of the tub where the metal lath is rusty, behind the faucet where there are water stains, and (maybe) directly below the tub drain/water inlets where it appears that the plaster wall is bulging. Pics below.

It is not uncommon for a tub/shower wall to leak or a caulk joint leak, or an overflow gasket leak, any of which could allow shower water to end up in the wall cavity and/or underneath the tub, which can allow for the growth of mold/mildew and rotten wood, all of which will produce an odor.

 

[CountryBumkin]

Al, I've been re-reading the thread and I want to clear up something on the picture you posted. Is the flange at the top of the photo the Tub "overflow" flange or is that flange really at the bottom of the Tub (the drain)? If it is the drain (I assume it is as it connects to p-trap) where does the overflow connect to the drain pipe (behind the electrical conduit in that view?)? I'm having a hard time figuring out how the photo is orientated.

 

[Sponsor]

 

[AlGreen]

You're right, that is confusing. The flange up top is for the overflow. In the new pic below you can see the tub drain.

 

[CountryBumkin]

Makes sense now.
It was mentioned earlier that the pipe sticking up with the cap is, is where the Air admittance Valve (AVV) would be installed. You removed the cap to see if that help with the gurgling noise (which it didn't) but it's purpose is to prevent the Tub p-trap from being suctioned dry when the tub drains. If the tub p-trap does not hold water you will get that sewer smell out of the tub drain (not so much in that space in the photo, but in the bathroom).
It might not be your problem, but for a couple of dollars, I would put an AAV in. I assume there was one there at some point, but you or previous owner removed it.

I'm not a pro, so maybe wait for a pro to advise on this.
Good luck

 

[Cacher_Chick]

There should have been a vent there, but it is quite apparent that someone has made some changes. This may be completely besides the point if the issue you have is with the sink, and the problem started long after anything else was changed.

If your sink drain is partially clogged before it hits it's vent, that will cause your gurgling sink too.

 

[AlGreen]

Thanks everyone. I'm going to check the P trap in the sink and perhaps snake the pipe after that point. I'll also add the AAV vent to the tub pipe, as suggested.

Now I'd I could just figure out the source of that smell...

 

[AlGreen]

Does Oatey make a smaller Sure Vent that will screw into the pipe shown in the photo? The 20 dfu one I bought will require using cement, which I can do if I have to.

 

[CountryBumkin]

See http://www.oatey.com/products/air-a...ure-vent-air-admittance-valve-20-dfu-capacity
or
https://www.zoro.com/studor-air-adm...gclid=CLCF96Sjo84CFQdZhgodAmYAUQ&gclsrc=aw.ds
I would try local HD or Lowes if your in a hurry.

 

[AlGreen]

Thanks. The one I bought has an adapter like the model in your first link. I'm just not seeing how even with that I can connect it to my pipe. (I'm sure I'm revealing my inexperience here.)

 

[CountryBumkin]

Unless I'm missing something - it looks like you just need to unscrew the cap with a big adjustable wrench and then screw in the new AAV. The adapter (that glues onto the PVC pipe has the internal threads) isn't needed since you already have that piece installed.
Didn't you say earlier that you were able to remove the cap?

 

[AlGreen]

I thought it would be that simple too, but the AAV is too big to thread into the pipe, even without the adapter.

 

[AlGreen]

Any other thoughts on this before I return the Oatey AAV?

 

[CountryBumkin]

Looking a the Studor product guide http://ipscorp.com/pdf/studor/Studor_Technical_Manual.pdf
it looks there is an AAV model with 1-1/2" threads. I would think Oatey and all the other brands would have similar models.

I'm assuming the AAV you have in your hand now is 2" thread. Is this correct? Have you determined that 1-1/2 is the size you need (did you measure the plug you removed)?

 

[AlGreen]

The male threaded end of the AAV I bought measures 2 inches. I just checked the pipe I wanted to install it on, and the female threaded opening is 1 3/4...

Is there some kind of reducer I can use if I screw the AAV into its adapter that will go from the adapter to the female threaded 1 3/4 inch opening?

Looking a the Studor product guide http://ipscorp.com/pdf/studor/Studor_Technical_Manual.pdf
it looks there is an AAV model with 1-1/2" threads. I would think Oatey and all the other brands would have similar models.

I'm assuming the AAV you have in your hand now is 2" thread. Is this correct? Have you determined that 1-1/2 is the size you need (did you measure the plug you removed)?

 

[CountryBumkin]

I've never heard of 1-3/4 schedule 40 PVC. I think maybe you are measuring the outside diameter instead of the inside. I'll bet you have 1-1/2 PVC. See https://formufit.com/pages/pvc-101

You may need to get an internal 2" thread to a 2" slip fitting, and an external 1-1/2 thread to a 2" slip fitting and connect the two together with a short piece of 2" pipe. Or some such made up adapter. Or, if it's not too hard to reach, cut the existing fitting with cap off the pipe and glue your adapter piece to it.

Or take the "cap" and the AAV to Home Depot or a Plumbing store and show them what your trying to do.

 

[AlGreen]

I definitely measured the inner diameter, and it was 1 3/4. I'll measure again just to be 100 percent. But before I do, can I even have an AAV in a access space with a closed door? I thought they needed airflow.

 

[CountryBumkin]

Typically AAVs are installed under sinks which have less air flow than your space.
But there isn't much air flow needed, its just when the Tub is draining fast, then it lets some air enter the pipe so the fast flowing water flow doesn't create a suction and suck the p-trap dry (that's when you start getting sewer gas in the bathroom). When the tub isn't draining the AAV is closed so no air/gas can escape (that's the downside to an AAV - the valve can go bad and stick open, then sewer gas gets in your home).

 

[CountryBumkin]

It's hard to measure the OD of a curved surface (Pipe) without a set of calipers.
If you can get a measurement - this is what you should get if you have 1-1/2" or 2" schedule 40 PVC.

 

[AlGreen]

Thanks. I'll check the O.D.

 

[Reach4]

Or take the "cap" and the AAV to Home Depot or a Plumbing store and show them what your trying to do.

That works best.