Need some help from plumbing gurus on a sewer gas smell

[Baja 252]

I've got double bathroom sinks that have worked fine for years. I replaced the faucets and drains (pop up drain vs the knob you pull up). Now when you turn on the water you get a sewer gas smell coming out of the sink over flow holes. There is no smell any other time if you don't turn on the water. What the heck did I do wrong?
I removed trap, it's full of water, how the heck is the smell getting past the water filled trap?
Let the sink sit over night and checked trap again and it's still full of water.
Used a plunger on the sink.
Ran tons of hot water down the roof vent, it flows great, not plugged up. Other sinks that I think are on the same roof vent don't smell.
Ran a snake thru the pipe going into the wall just to be sure.
Nothing makes any difference, still have strong smell when you turn on the water.

What am I missing?

 

[ltbaney1]

is it only when you run hot water? i had that issue in my upstairs master bath sink. only when you turned on the hot water. never noticed at any of the other taps, so i did the same thing you are doing. chased the drains. a couple days later i noticed it in the shower as well. turned out my water heater needed an anode rod and flush. no more smell.

 

[2Driver]

Could it be barking out the sink overflow hole? Something got in there and water pressure going down the drain is pushing air back up the overflow. Just a guess.

 

[Mandelon]

Perhaps it is not sewer gas, but just gunk in the drain or overflow?

 

[Boat 405]

I've had to clean out the sink overflow holes with a large pipe cleaner tool. It had some nasty stuff in them

 

[JL95]

I am dealing with the same thing in our master bath double sinks. Makes me wonder as well.

I have 2 bathrooms with the pop up style drains and they get absolutely nasty...

 

[yz450mm]

Close the drain and plug the overflow hole, then turn your hot water on and see if you still have the smell.

P traps can get really nasty, throw a new one on there or thoroughly clean out the old one and see if that helps.

Run some boiling hot water down the overflow and drain.

 

[FreeBird236]

I'm thinking you changed the air flow and you're smelling old stuff inside the existing pipes. Might try some bleach, but it could corrode the pipes depending on what you have.

 

[Baja 252]

Smell is definitely sewer gas and definitely coming from the overflow hole. If I plug it, no smell at all. All pipes and overflow drains are clean. I'll check if smell is there when you turn on both hot and cold.

 

[LHC Kirby]

Did you disconnect the P-Trap when you did the work? IF not, get that off and I'm guessing it's yucky. While it's off, with a bucket under the drain, run the water..... still stink? clean the trap real good since you have it off. If the stink is still there, I would plug the drain and fill the sink to the overflow and above. With water and bleach, and let it soak maybe run a "pipe cleaner" type thing into the overflow and try and clean it. (Bucket under the drain) , I would let it soak over night.

Please let us know what the end result is.

 

[boatpi]

All above and pour some bleach in the drain, let it sit overnight.

 

[spectra3279]

Get a gallon of peroxide. Pour in drain slowly until the foam comes back out the drain. Then use a small hose and get it in the vent hole until it's foaming out the vent. Let sit an hour and do again

 

[yamadog 426]

I had the same problem. The overflow hole on the sink did not match the drain on the sink. Took the sink drain apart and there was about 3/4” of smelly crap trapped below the drain hole. Had to make the drain hole on the sink pipe match the overflow. It’s been good since.

 

[rrrr]

I had the same problem. The overflow hole on the sink did not match the drain on the sink. Took the sink drain apart and there was about 3/4” of smelly crap trapped below the drain hole. Had to make the drain hole on the sink pipe match the overflow. It’s been good since.

This. On some drains you have to clock them to match where the overflow opening in the basin joins the drain.

 

[yamadog 426]

This. On some drains you have to clock them to match where the overflow opening in the basin joins the drain.

Mine was clocked right. The drain hole needed to be extended. The crap was trapped between the pipe and the bottom of the sink where the drain pipe bolts.

 

[Orange Juice]

overflow is on wrong side of P-Trap.

Got any pictures? Also, pictures of shower?

 

[lbhsbz]

Last time I had this happen the drain pipe downstream of the P-trap was about 1/2 full of some stanky goo mess. Cleaned that out all has been well for several years now.

 

[HOOTER SLED-]

Drop some tic tacs in there...lol

 

[havasujeeper]

Once a month, I sprinkle some baking soda into my sink drains AND overflow drains. I then pour a few cups of cheap white vinegar into the drain. You'll see it bubble up, scrubbing the drain lines. Let it sit for 20 minutes, then flush with hot water.

 

[DLC]

If you think it’s in the sink

get a
1.5 PVC ball vale
1.5 close nipple
1.5 drain nut w/ washer they have a 1 1/4 to 1 1/2 nut & washer

Take apart the drain line leave on the tail pipe
use some Teflon tape on the 1.5 nipple - thread into ball valve

slide nut and washer on the tail pipe
slide ball valve onto tail pipe and thread nut / washer on ball valve

turn valve off check for leaks let it sit for a few minutes

if it holds water add bleach & water and fill up to the over flow make sure it’s full

grab a 5 gallon bucket - turn ball valve to drain sink refill and flush a few times, dump / empty bucket in toilet or shower

once clean put drain line back together

parts needed -