Bad Sewer Smell when Driving

[Mike Wahl]

We do a lot of boondocking with our 2001 Signature and we have several places we stay that a dump station is not available.   This isn't a big deal because we have one close to our home that we can take the coach to and dump.  The problem we are having is, once we start traveling down the road we get a sewer smell in the coach.  The smell seams the strongest in the bathroom.  I made sure all the sink and shower traps had water in them.  I have tried adding chemical.  The one think I noticed was the seal on the toilet would leak allowing the water to drain out.  I fixed this, however it didn't fix the issue.  We have had no issues while parked.  I'm wondering if anyone has had this issue and what the cause/fix for it was. 

Edited August 22, 2022 by Mike Wahl

[Tim-AZ]

My guess it is your tank vents under the sink. Check them all.

Tim

[bklaes]

I just went through this exercise.  Many good suggestions here https://www.monacoers.org/topic/4867-grey-water-stench/#comment-45173

 

Good luck,

[Chargerman]

When I had this problem I installed a Cyclone vent on the roof. Inexpensive and easy fix. Have never had the hint of a smell since. 

[Nevada Rob]

We had the same type of problem. It turned out to be the flexible sink drain line that moves with the slide out. A small crack in the top side of the flexible hose. I figured that when driving there was just enough pressure put on the vent pipe to send the smell of last nights dinner and peaches and all types of good smells to percolate into the coach.

[RoadTripper2084]

Could be your toilet floor/flange seal needs to be replaced. Had a similar issue with my rig this year and that fixed it. 

I found the plastic flange was only screwed to the floor well on two sides and the parts that the toilet bolts mounted on were pulled up away from the floor, breaking the seal. I added additional screws to the flange and a new seal, problem solved.

 

[Tom Wallis]

We used to have the same problem. It only occurred while driving with a front window open. Apparently that causes a negative pressure inside and we got a bad smell from the bathroom. I installed the a 360 siphon on each roof vent and never had it again.

https://smile.amazon.com/Lippert-Components-389381-Siphon-Roof/dp/B01CZQ9Y6M/ref=sr_1_2?crid=B2KNB91EVLBO&keywords=360+siphon+waste+vent+for+rv&qid=1661230787&sprefix=360+si%2Caps%2C175&sr=8-2