Sewer Smell

[Dogpa]

I have a 2005 Mandalay 40B and have owned since 20,000 miles, has 34,000 now. It has always had a bit of a sewer smell when driving. I do not run with vents open, both tanks have been bleached but on recent trip I received smell through dash A/C, crazy right? I had in shop and they replaced the pop vent valves,(3), saying they were bad and that was the problem. Drove away 20 miles to next destination and same thing. Any suggestions? I did call the repair facility and they advised to clean tanks, which I had already done.

[TechWriter]

But wait . . . there's more . . .

My Mountain Aire has a Lil Stanker 12V fan installed on the top of the black tank stack.

Works great. Also noticed that after I installed hoods over my roof air vents, smell pretty much vanished.

[booty51]

all posters giving good advice, I have never smelled boiled over batteries so I don't know about that,but checking the undersink vents is a good idea,also the toilet we have has an overflow tube in it that goes to the black tank. I was told that it is like a P trap also and would evaporate out like the other traps. So see if you have this overflow it could be dry allowing odors in as well. Ours stunk when we first got it too. I flush like crazy when I dump, pour a little chemical in shower kitchen and bath sink drains and treat both black and grey tanks, odor has gone away when driving. I also fill toilet up to go out overflow when making ready for a road trip, just some Ideas.

[TopTech_Racing]

Most of the time the bathroom sink is plumbed into the black water tank, I was told this was to keep enough water in that tank. I find that if you close the drain stop on that sink there is no smell coming from that area while traveling.

[Dogpa]

Not sure how to check the batteries but that area always seems dirty but I do not see signs of the fluid boiling over. Had shop check electrical system and was good. Two batteries new 5 two years old..

[bigjohnmcvicker]

Are you sure its not from the batteries?

[Executive45]

Finally, check the "P" trap in the washer....if you haven't used the washer in awhile, the water evaporates and will allow a sewer smell back into the coach....Dennis

[mlts22]

I'd check the AAVs (air admittance valves) which likely are near sinks. These allow air in, but not out, and sometimes the diaphragm fails. Fairly easy repair, just unscrew the old one, screw in the new one, call it done.

[Wheel_Estate]

there are 'vacuum breaks " like what goes in near washer or dish washers in the home, on some MH .... time allows them to dry out and seep odor from the GRAY tank

[barnaclebill]

SkiingSixPack wrote:
On our much older motor home, what I thought was sewer smell turned out to be my coach batteries boiling away creating a sulfuric smell that I and others blamed on the sewer. My converter was bad and overcharging the batteries.

Maybe it is a bad alternator over charging your chassis battery??? Just a thought and something that is probably pretty easy for you or a tech to check out.

Good idea!

[Jim]

You can get plastic plumbing 'T's for $3 each, in the bathroom repair section of Home Depot. Works just as well as the commercial device made for RVs at 1/10th the cost.

[SkiingSixPack]

On our much older motor home, what I thought was sewer smell turned out to be my coach batteries boiling away creating a sulfuric smell that I and others blamed on the sewer. My converter was bad and overcharging the batteries.

Maybe it is a bad alternator over charging your chassis battery??? Just a thought and something that is probably pretty easy for you or a tech to check out.

[Dogpa]

Thanks for the quick response ans I will research.

[1492]

Welcome to the Forums! 🙂



Moved from Forum Technical Support

[parkdep]

This is what I used, easy to install and took away sewer smell completely Sewer Vent