Sewer smell/Trap access?

[CCF]

We moved into our recently remodeled, late-50s ranch home last summer. The previous owner did most of the remodeling work himself + favors from construction and trade companies.

In the (mostly finished) basement, in the rec room, there is capped off plumbing for a future sink/wetbar setup, with a Studor Mini-Vent above. The smaller drain line is capped with a 1.5" knock out plug, and the other larger (cleanout?) line has a larger metal plug. I don't know the right terminology.

[Please see pics]

Anyway, there is a godawful smell seeping into the room from the small drain line in spite of the plug. Based on my newfound yet limited plumbing knowledge, I'm assuming that there is (hopefully) a P- or S-trap in the wall behind this opening that has just dried up and the fumes are therefore getting in. But I wouldn't be surprised if some of this were done incorrectly, since we've found other issues with things like plumbing and electrical, post-move-in, that were not caught during inspection.

If a dry trap is indeed the problem, how would one go about accessing it to refill? Or is this something that would require us to call in a professional?

 

[Reach4]

Anyway, there is a godawful smell seeping into the room from the small drain line in spite of the plug.

You are saying there is a strong smell in the place shown in 3.jpg I think.

There would be no trap behind 3.jpg.

Try putting thin plastic over the smelly thing, and secure it with a rubber band. If that does not stop the smell, try isolating areas with thin cheap plastic drop cloths held in place with masking tape. Sniff each side of the drop cloth to see which side has the smell.

No strong smell from the 5.jpg area, right? If in doubt, cover that with a plastic bag and seal with tape or rubber band.

Now if you want to put a sink there some day, you could glue in a trap adapter. There must be something that could reliably plug an unused trap adapter. The advantage of a trap adapter is that it is ready to add a slip drain line to later. I would just make sure that your current workaround stops the smell.

 

[Sponsor]

 

[CCF]

Ok, so we would have to complete the plumbing (install a P-trap) for a sink, etc. for it to be properly sealed then, right?

Smell is definitely coming from picture 3. Is there any better semi-permanent solution for that? Better seal/plug product, etc. than whatever plug is in it now? Have the plastic wrap on it now.

 

[Reach4]

Is there any better semi-permanent solution for that? Better seal/plug product, etc. than whatever plug is in it now? Have the plastic wrap on it now.

Instead of rubber bands, I really like the bands made of EPDM. They last a lot longer. There is a lot to be said for electrical tape too. It lasts nicely. It is available in different colors.

I am not sure that test plug is even glued in. You might be able to pick that out rather than breaking it out.

If you glued a trap adapter in there, you would be ready to add slip tubing for a drain. The Sioux chief Quickplug 234-QP2 (1-1/4) or 234-QP (1-1/2) https://www.siouxchief.com/products/drainage/testing/test-devices/miscellaneous/quickplug could be used to plug that temporarily and look pretty good.

 

[WorthFlorida]

You can get a length of 2" PVC pipe and one of these DMV flexible end caps. The pipe inserted into the wall pipe should be tight without any cement. If it's a little lose just tape it up at the connection to seal it.
https://www.homedepot.com/p/2-in-PVC-DWV-Flexible-Cap-PQC-102/100372303

 

[Reach4]

That one is 1-1/2.

 

[CCF]

Thanks to all for the help. Cling wrap doubled over with a couple rubber bands is currently doing the trick. Should have done that a long time ago! We’ll look into the other temporarily plug solutions as well.