Sewer smell problem

[Horst]

I have a rear kitchen which I'm quite has not been modified with respect to plumbing, and my bath sink empties into the black tank.

[HPotter]

On rear kitchen models the shower and bath sink both empty into the black water tank, along
with the toilet. The outer dump valve is the black water dump. I always dump this first, that way when the sink water is dumped next, it helps to flush out the hose.

Harold, #886.

[Charlie]

I have a '79 side kitchen, rear bath I just bought in March and I was experiencing the same problem you have.  I actually found several problems with mine so I'm not sure which problem was causing the smell but I will list the items.  First, the toilet flush valve was worn out so I installed a new Thetford toilet.  If you do this make sure to pull the carpet out from under the toilet.  Second, someone had changed the plumbing from the bath sink so it drained into the grey tank.  Only problem was that they used a small hose instead of ABS pipe and gunk had built up in it so it drained very slow and would emit a sewer odor.  Then I found something really weird, when they cut off the pipe from the sink to the black tank, they installed a cap "vent" on top of the pipe going to the black tank.  If yours has been modified you might want to check for this and remove it.  Third, the black tank vent pipe to the roof runs up in the storage cabinet between the bath and door.  At the top the hole was about 1/4 inch to big and wasn't sealed so fumes could come back into the coach.  I silicone around the pipe.  Anyways, after all this and putting the proper amount of chemical in the tanks I haven't had any smell at all, vents and windows open or closed going down the road.  If you want more info on this problem and my fixes, my email is NetConnected@hotmail.com   Good Luck