Bathroom smells when traveling down the road

[Tockert]

This is probably an easy fix.
We just finished a week long trip from Texas to New Mexico over the Labor Day week.
While traveling down the road, we would notice the fumes from the black tank coming back into the coach.
It was worse in the bathroom.
I was afraid to open the vent above the toilet while running down the road, as it seems a little flimsy.
It seemed worse if we had a strong cross wind while traveling.

We stopped at a CW on the way home and bought a vent cover and the vent tube vain looking thing for the vent tube.
I hope these two things will help or fix this issue, as it was strong enough to almost make my wife sick if she went back to the kitchen area.

Thanks

Todd

[jd99336]

Mine does it too, my DW describes it as an "earthy smell". But it only does it if I roll down our door windows when going down the road. Somehow it is pulling the vent pipe fumes in as the toilet remains sealed, and only when the black tank is in full "ripe" mode.

We always leave our roof vent open in the bathroom, so that apparently doesn't stop it.

I suspect it is just various pressure differentials with the airflow and likely varies from unit to unit.

[Grumpy]

Originally Posted by Tockert

While traveling down the road, we would notice the fumes from the black tank coming back into the coach.
It was worse in the bathroom.

We had a similar issue with our 01 and it turned out to be a broken toilet flange. The pipe broke right where it screwed into the flange, so that might be something else to check.

[EA37TS]

Two things to check.

Make sure the vent tube is sealed around the roof. If not adequately sealed the sewer gases/smells could be coming back in through the roof and wall cavities.

Second, is the bathroom sink drain plumbed to the black tank. This is the case in many RVs and if there isn't enough water in the P trap smells can come back through the sink drain. The P trap can dry from lack of use or water jostling around during driving. You can try plugging the drain of the bathroom sink when driving and see if that makes a difference.

[Tockert]

Thanks for the replies.
Never thought of checking the bathroom sink drain.

With looking at the way the roof top vent is covered, I thought maybe the wind was pushing air into the tank, and it was coming up through the toilet.
I even tried adding extra water to the toilet to create a better seal possibly.

I will add the roof top vent cover so the vent can be opened while going down the road, and the other weather vane looking vent tube cover also.

Thanks

Todd

[Tockert]

After our last campground, I dumped all the tanks, and made sure to flush the black tank really well.
I did it long enough that I had clear water coming from the tank when I dumped it.

Todd

[Camper_bob]

Let me know if the new vent stack cover helps.

We have a similar issue, but only if the toilet valve is opened while the rig is in motion. I'm sure it has to do with pressure diffs from the vent stack going 65 mph down the road, and the fact that the sewer vent is literally inches from the roof vent, which we tend to keep open (Maxxair vent cover).

I've tried it several different ways, and have not been able to completely eliminate the intrusion. Best success I've had is to close the vent, and close the toilet valve JUST before all the water has left the bowl. But like I said, it only really happens while in motion (or if I leave the vent fan on while flushing when parked...)

[Harvard]

IMO It is the reduced pressure inside the house while in motion. I had to put the rubber sink stop in the bathroom vanity when in motion. Yes, our bathroom vanity is plumbed to the black tank.

[Superseneca]

I have found that I must close all roof vents and house windows to avoid any odor issue. Also we keep water in the bowl.

[Camper_bob]

Always keep water in the bowl. Last thing you need is that seal to dry out.