Sewer gas issue

hostage wrote:

rgatijnet1 wrote:
For whatever reason the vent on your roof is capturing the outside air and forcing it down the pipe in to your RV. If you have anything on top of the PVC pipe, try taking it off and see if that fixes the problem. If it does, just get a standard vent cap.

how could that be? the black tank only has one vent and thats the roof out to atmosphere; the only other is the toilet and the seal would have be shot(wont hold water) and surely a owner would know this
and the seal would have to be incredible worn for it to actually escape enough through this seal to cause a problem from driving down the road

There's a very simple reason how it could be. If you have a window open in the RV while driving, say the drivers window, the slipstream causes suction, which causes negative pressure inside the RV. That can cause holding tank fumes, grey or black, to be sucked inside the RV. Grey tank smells can be as bad as black tank smells.

Reasons are numerous but can include a dry P trap on the washer drain, a dry P trap on an unused sink, a weak seal in the toilet, etc..

Those old style dome vent covers on the roof use to be famous for allowing smells inside with the drivers window open. There are commercial devices for that, but I just put a bathroom sized PVC 'T' on the roof in place of those dome vents and the wind from driving, caused slight suction in the tanks which allowed opening the drivers window with no smells.