Mysterious Toilet Issue

[mtoz1223]

Hey y’all,

I’m experiencing some very strange issues with a toilet not flushing properly. First, I’m on a septic system, but there is no sign of any other drains draining slowly/backing up, or sewage gas smells. Having it pumped/serviced tomorrow also.

The toilet has been working fine for four years since buying the property and just a month ago started not flushing. It fills the bowl, then drains very slowly after. Had someone come out and they augered the toilet/drains and blew out the vent pipe with a shop vac, and this seemed to fix things for about 3 weeks, until now. I installed an air admittance valve on the vent pipe to keep debris/critters out, and the issue immediately started up again.

The vent is a 1 1/2” pipe that I *hope* to be installed properly…it is coming down vertically into the drainpipe and vents into a utility room accessible from outside the house. I removed the studor valve and augered the vent pipe, and it fixed itself for one flush, then started backing up again. Had a plumber out, they removed toilet and inspected it thoroughly, flushed drains and toilet, augered drains, augered vent. Said no clogs in drains, nothing visibly wrong with toilet, and suggested putting aav back on. It worked for maybe three flushes and started not flushing again. Only thing plumber suggested was replacing the toilet…but also that it seemed to be perfectly fine and that there were no clogs in drains. (Also, all other sink/tub drains above and below the toilet drain perfectly fine). It seems to fix itself for a flush or two intermittently…but now is just blocked up.

The last resort seems to be replacing the toilet and hoping that works…
My only other thoughts are that toilet not set level or vent pipe may not be adequate/installed properly, or that this aav is somehow causing an issue with back pressure? I’m no plumber, so this might be off the mark. It does feel like it could be an issue with the venting, but it has been working for years with the current set-up, without aav.

Very confused. Any suggestions for troubleshooting this would be appreciated.

 

[Twowaxhack]

Take the toilet out in the yard and set it up on blocks to test flush it repeatedly.

 

[Twowaxhack]

Also while the toilet is removed use a 5 gallon bucket to repeatedly dump in water through the flange.

 

[mtoz1223]

 

[mtoz1223]

Thanks for the reply. I’ll try this if I start to think it’s the toilet again…

So I removed the Studor valve, blew out the vent again with a shop vac, and it flushed properly twice before backing up again. On closer inspection, the vent pipe is installed in a crazy way. It comes in from the side, not from the top and has a p-trap. It seems to me this is filling with water and then not allowing any air to flow in from the vent when it’s flushed. I’m attaching a picture, hoping someone can confirm this is as crazy as it seems to me, and why anyone may have installed the vent like this in the first place.

 

[Twowaxhack]

Vents don’t have traps. So that’s not a vent.

 

[mtoz1223]

That’s why it is strange. That pipe goes through the wall, elbows to vertical and terminates with an opening, going to nothing. It seems like an old bit of plumbing that has no purpose. Maybe was a drain at one point and didn’t get capped, I dunno. A handyman came out and recommended to install a Studor valve on this “vent”

 

[TomFOhio]

Pull your toilet and before putting it on blocks first lay the toilet on its side and take a flash light and look up in the
drain hole and make sure there isn't a foreign object in the trap. If you don't see anything then pour water in it
like suggested. Like TW said vents don't have p-traps on them. it's probably an abandoned line. I'm surprised your not
getting sewer smell out of it.