Gray tank smell from under shower 2013 36M

[cruizerEd]

We get a grey tank smell from under the shower. When it is hot it can be very intense. When it is really really hot we get little black flies.

I think it is actually coming through the holes in the floor under the shower and collecting in the space above the floor and below the shower pan.

I does not seem to be coming from the grey vent which is about 4 feet forward of this. I have opened that area up and it doesn't smell bad. It also doesn't seem to smell as bad in the wet bay which is right in this area nor in the basement which is connected but only by a very narrow slot up close to the floor.

The bathroom exhaust fan pulls the smell up into the bathroom if the door is closed.

Of course all of this assessment is by nose and although it is my best guess about where it is coming from it is hardly a definitive analysis.

Anybody have this issue and get it resolved.
Can you tell me what it was or might be?

Thanks

[DKY]

I had a problem like it on my 36' Journey but it was the black water tank. On top of the tanks there is a rubber fitting for the 1 1/2" pvc vent pipe to fit in . Mine was put in too short it sat just on top of the rubber fitting ,it sealed for a few years then I had the same problem . My vent pipe was sealed at the roof so I had to cut the pipe push it in the rubber fitting and connected the pipes with a rubber hose and two clamps .Also check the one way vent under the sink some times the rubber flipper sticks open ,that will give you gray water smell .

[grtharris]

cruizerEd when they cut the opening for the p-trap under the shower they do not cut through the bottom plywood so if the p-trap is leaking the water will just sit there. There is also a vacuum break unit behind the shower that could be leaking fumes.
Looks like there is a access plate behind the shower in the bedroom when the drivers side slide is out.
Plumbing drawings are at: http://www.winnebagoind.com/diagram/...p36m_plumb.pdf

[Jupiter]

Ditto on the vacuum breakers. Had the same smell in our 36M and found the vac breaker under the sink was the culprit. I sealed the unit with tape temporarily and it ended up as a permanent fix. Water drained just fine out of the bowl with the vac breaker taped shut.

I also cut and placed a large white sheet of magnetic rubber on the louvered opening at the shower threshold. I never could understand what its function was, but I felt better with it sealed.

cheers,
Joopy

[cruizerEd]

So here is the update:

Thank you for the very specific tips and the drawings.

After flushing the tank a few times I filled it to overfull such that water collected in the shower floor.

I waited a while and although the water went down a little at first it eventually held level.

From this I concluded that I had no leaks below the level of the shower. Or at least very small leaks that could not possibly make that smell.

I used a camera to get a shot of the gray tank vent while the tank was overfull and there appears to be no water around it and it looks attached. See picture.

The drain from the slide is easy to get to and also was not leaking.

I can not get to where the drain from the shower goes in but it wasn't dripping water.

As it so happens I just re-sealed the 360 siphon vent on the black tank and while I was up there I pulled on and wiggled the pipe and it seemed attached.

I removed the vacuum break under the shower and inspected it and tested it it seem fine. I put it back on taped up. This had no effect the smell was still intense and would not abate.

I canceled my service appointment and called a mobile tank cleaning guy who has a pressure washer and some drain equipment and he came out and rinsed the tank. The company was Royal Flush of Yuma. Not impressed.

Once he started spraying however the smell seemed to come from everywhere so I so I wonder if the tanks and fittings just aren't up to a very ripe tank and smell just permeates the materials. Normally it only stinks when it is really hot, like over 90 all day and it wasn't very hot when he was cleaning and had not been stinking for a few days.

After he was done I rinsed again a few times and again overfilled with the same results.

My gauge is still stuck at 2/3 and although not the issue at hand I was kind of hoping the tank wash would clean that up.

One remaining disconcerting symptom was the tiny black flies that were in the area around the shower (not sure if they were under the shower) The only other time I have seen these was when when I had the plumbing open. These flies (and the smell) are why I thought there would be a hole in the system somewhere. Again the flies were only there when the coach was 100 degrees. Haven't seen them since.


I am going to order one of these USB Endoscope for the next time I need to see something hard to get to.

I may try to build my own flushing system. Maybe tie it to the hot water pressure relief valve and put a 360 sprinkler head on a thin hose.

Thank for all the tips. I'll keep trying to find this leak if it really is a leak and not just a systemic design flaw.

[pyoots]

Hello ED,

My experience with a stinky gray water tank arising from shower/bathroom sink/ kitchen sink has gotten solved by pouring water along with a sweet smelling deodorant for that purpose. From time to time I've also filled and flushed the gray water tank. It's not unusual for us to have more unpleasant odors coming from the gray tank than the black. Another cause can be that water needs to be in the traps to block the methane smell from being a problem. JMHO

Phil

[Forza Tom]

Originally Posted by pyoots

Hello ED,

My experience with a stinky gray water tank arising from shower/bathroom sink/ kitchen sink has gotten solved by pouring water along with a sweet smelling deodorant for that purpose. From time to time I've also filled and flushed the gray water tank. It's not unusual for us to have more unpleasant odors coming from the gray tank than the black. Another cause can be that water needs to be in the traps to block the methane smell from being a problem. JMHO

Phil

Saw this yesterday and thinking about installing them.

Hepvo Waterless Valve

[Barny750]

I found the stinky smell comes from bad engineering. The vent for the black water tank was put to close to bathroom roof vent. The gasses are venting out the roof and going back down the roof vent in the bathroom. We were keeping the vent running to keep the smell out. I put a riser and elbows on it and vented away from the roof vent. Problem solved.
Unless its hot and wind is in wrong direction.