I ran across this in the kitchen cabinet next to the kitchen sink. Just randomly there in a separate cabinet. Customer is complaining it is occasionally leaking. You can actually see the water stain marks onto the bowl although it is currently dry in the picture. Is it a cleanout?? How do I fix the leak? I’m not sure if the cap is glued in or not. I did not try to open it.

[i.postimg.cc]

It's a cleanout plug. Unscrew it and put PTFE(Teflon) tape or plastic suitable paste sealant on it and reinstall.

steve….....are you sure that's not an AAV?

I'm positive. 2" flush plug.

for about a buck, replace it with a square head threaded plug.

ditto

flush plug

(a mason's chisel is a good tool for unscrewing - will fit the slot)

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Thanks, ALL!! I return to the job site next month and will remove, teflon tape it back, or put in a newer square throat cap. I wonder if I can rig something to remove instead of a masonry chisel, maybe a piece of stiff metal/angle iron type and turn with crescent wrench. I'll have to get creative.

I think I'll invest in this cool tool. Should work with the slot I have plus square plugs:

[www.amazon.com]

I bought this a while ago, it's all solid metal.

Wow. Yours definitely means business!!