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zach477's avatar
zach477
Explorer
Nov 27, 2015

Replaced air admittance valve, Still stinks.

Today I replaced the air admittance valves under the kitchen and bathroom sinks. I was getting oder under the sinks while driving.

After I took a shower, I noticed the same smell from under the kitchen sink, but not the bathroom sink. This was my last shower before going to the dump site tomorrow. The grey tank has been "full" for a day or two, but no water was coming up in the shower so I figurd I'd be fine.

Even with a full grey tank, the AAV shoukd still be doing its job, right? What gives?
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16 Replies

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  • mikestock's avatar
    mikestock
    Explorer
    Dec 19, 2015
    Been fighting this battle with the AAV located at my washing machine drain. I first tried replacing the original with the Studor. No help. Considered piping the vent straight up through the roof like the black water vent and the other gray water vent from the front of the coach. Haven't done this yet but did install a 1-1/2" quarter turn valve below the AAV and only open it when using the washing machine. The vent in the front of the coach does vent through the roof. I guess the one at the washing machine is only there to prevent the trap from being sucked dry.

    One thing we do now is to make sure we clean dishes and remove all grease, as much as possible, before washing the dishes. We also add deodorant to the gray tank, which I have never had to do before.

    Problem seems to be solved.
  • zach477's avatar
    zach477
    Explorer
    Dec 19, 2015
    Here's and update. I made it three weeks until my tanks were full and needed dumping. I didn't let them get as full as last time but I definitely went a couple of days past when the tank meter said they were full.

    I still noticed an odor once I started driving to the dump site, but not as bad as previously. It was definitely the grey tank. Usually I get the black tank smell while driving so I guess this is an improvement.

    I checked under each sink and the air admittance valves seem to be doing there job now because the smell wasn't coming from there. I had drain plugs in the bathroom sink and shower, so I'm figuring it must have come up the kitchen sink drain.

    I'm happy that I'm not getting black tank odor while driving anymore....even though I didn't do anything any differently so I don't know why it went away. And I'm glad the new air admittance valves are working better than the old ones. Next time I'll plug the kitchen sink drains and see if it improves.
  • zach477's avatar
    zach477
    Explorer
    Nov 28, 2015
    I really only notice the smell under the sinks when the grey tank is full. And it is definitely coming from under the sink. I just emptied the tanks today so it'll be a week or two before I can do more diagnostics.
  • rgatijnet1's avatar
    rgatijnet1
    Explorer III
    Nov 28, 2015
    On your toilet, you have a gasket that seals at the top inside the bowl. This gasket moves every time you flush the toilet and is subject to wear. If your toilet will not hold water for an hour or so, it could be that air/odors are coming directly from your black tank around the upper toilet gasket.
  • wildmanbaker's avatar
    wildmanbaker
    Explorer
    Nov 28, 2015
    You may also have a cracked or broken drain line, allowing some gray water to spill out, and when it evaporates, you get the smell. A whitish or grayish residue where it drips or is leaking could be a tell-tale sign. This problem could be under your floor, and very hard to find and fix.
  • Bobbo's avatar
    Bobbo
    Explorer II
    Nov 28, 2015
    rseymour21 wrote:
    Dumping your tanks might also solve your problem.

    Dumping the tank will NOT solve the problem. It only moves it to the next camping trip. The problem is still there.

    The plumbing system is designed so that, when working properly, no odor can get into the RV.

    I fought this battle for almost a year. I replaced the AAV's. I flushed and snaked the roof vents. I replaced the AAV's again. What finally worked for me was when I took the toilet up and replaced the rubber gasket between it and the floor/holding tank.

    But, you are right. After dumping the tanks, the odor went away. Until the next camping trip.
  • sdianel_-acct_c's avatar
    sdianel_-acct_c
    Explorer
    Nov 28, 2015
    If you check the valve and that's not it, sometimes our shower drain smells because it needs cleaning. You may want to try dumping 3 tablespoons of baking soda down the drain and then dump about a 1 1/2 cups of vinegar in the drain and let it sit for a couple of hours and then use boiling water to rinse out the drain.
    To keep the gray tank from smelling, we use 1 cup of powder Borax dissolved in 2 cups of hot water and 1 cup of Dawn Platinum dish detergent after we dump the tanks. No more odor.
  • Trackrig's avatar
    Trackrig
    Explorer II
    Nov 28, 2015
    Old-Biscuit wrote:
    John&Joey wrote:
    zach477 wrote:


    OP.......
    Did you use one of the inexpensive (cheap) AAVs ? $3-$5
    That just have a flapper pulled close by a rubber tang



    Studor makes a better one and more expensive $20+


    I agree the more expensive ones are better and bought them a couple of weeks ago when we started smelling fumes so I bought three of them. When I went to change them, there was only room to install the larger diameter one under the kitchen sink. Under the bathroom and bedroom sink they wouldn't work due to tighter confines. The little 6" riser the vents mount on came right up beside the sink. I spent a lot of time trying to find the vents with the smaller diameters - the cheap ones. So before you go to buy them, check if you have room for the larger / better ones.

    I changed all three and it got rid of the smell. I don't know which one was bad, but I didn't want to spend any more time on it.

    Bill
  • John_Joey's avatar
    John_Joey
    Explorer
    Nov 28, 2015
    zach477 wrote:
    Even with empty tanks, I there is an foul smell that creeps in while driving. I'd like to know where it's coming from.


    Smells are the hardest things to track down. Just wondering, how old is your rig? Seems like the older they are, the more smells they have from odd places.

    Something like this might help your current issue:

    Clicky
  • John_Joey's avatar
    John_Joey
    Explorer
    Nov 28, 2015
    Old-Biscuit wrote:
    Waste tanks do not have overflows.......EPA Hazard :B But the drain pipe and vent pipe going into top could be installed using a grommet vs being hard glued.
    With an overfull tank the grommet can leak


    I'm sticking to my story, because otherwise it means I need to fix the darn thing. I really don't want that job. :E

    As a side note, both the black and grey do this. It's an older Travel Supreme and it would not surprise me in the very least if they did plumb it that way. They seem to do things like that. When I get there I'll have to check the plumbing diagram to see if I can spot it.

    Your gasket concept does make a ton more common sense though.

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