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Dogpa's avatar
Dogpa
Explorer
Jul 17, 2013

Sewer Smell

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.

28 Replies

  • 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.
  • 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
  • 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!
  • 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.
  • 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.
  • Thanks for the quick response ans I will research.
  • Welcome to the Forums! :)



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