Sewer Tank Odor in RV Bathroom and Cargo Area?

[Booneyrat]

I have a 2017 337 RLS that recently started to have the same problem. When the black tank gets near full sewer gas comes into the living quarters. It starts in the basement and comes into the bathroom through the vent behind the toilet and also comes into the kitchen through open cabinet drawers that are opposite the bathroom wall. That is because the backside of these drawers are openly exposed to the basement storage where the smell begins. The smell is not coming from the AAV valves under the sinks. The sewer pipe and vent pipe for the black water tank are properly fitted and glued into place. My only guess is that the vent pipe detached itself somehow from the roof vent itself and under certain conditions the gas is coming back down the wall behind the toilet (because that's where the pipe is routed up to vent) and filling the basement with gas. This seems to happen when the tank is near full and it's cooling off at night. Never happened in the first 2 years of ownership. May need to putt roof vent cap and run a camera down it.

I had the same problem with my 2017 337RLS.I found the problem to be a black tank vent pipe on the roof was always full of water in cold weather due to condensation as the vent pipe runs parallel to the roof for a short distance after it comes up from the wall behind the toilet.At the time I solved the problem every time by using a blower that fills air mattresses to blow back through the vent pipe after dumping the black tank.It worked until the black tank got at least half full again...then blow it again.It was a poor design by those college boy engineers...I have since sold the rig and gave up full timing because of poor quality. Good luck.

[2goods]

Thanks for the reply. I think you may have a valid explanation. I went up on the roof, removed the vent cap and did see some water inside. But I would say only a third full or so. Lets say this is the problem and lets say draining the black water sucks some of this water down the pipe thus freeing up the vent to once again allow some breathing. So draining the tank more frequently helps keep the vent open. But what I don't understand is how the smell gets into the basement even with a passive restriction in the vent. The tank simply has a 4" pipe going into it from the toilet and the vent pipe going out from it to the vent. A sealed unit. The only way I see sewer gas escaping would be out the toilet bowl when the valve is open. Our smell starts in the basement. Got me stumped. I agree that quality is scary. Ben researching other brands but not having much luck finding quality workmanship in anything out there.

[Booneyrat]

Well...look how close the vent pipe exit is to your bath roof vent...if you leave that roof vent open any...the smell will get in.

[2goods]

It's not been open when this happens.