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Gray water smell mystery

Yahoo Message Number: 72213
Ever since I've had this RV, I've been cursed with gray water sewer odors.
With the aid of this list and my own research I have come up with several theories but have yet to come up with a permanent fix. The first discovery I made about 5 years ago, is that a relatively full gray tank, will blow out the water in the p traps (bath and kitchen sink) when going over a dip or frost heave. This is evident by the immediate smell and debris or crud splattered around the bottom of the bath sink. What I believe is happening is the gray water tank vent is unable to handle the sudden air movement caused by the water sloshing around thus blowing out the traps. It is somewhat explosive as at times there is considerable "stuff" at the bottom of the bath sink. The odor also comes from under both vanities and the source has to be the vacuum break valves. I don't think the valves are defective, but rather they "hiccup" and allow the vent to blow out on the sudden air surge.
To prove this theory, I have capped off the vents using a plastic bag and rubber bands. In general, there are no sewer odors under the cabinets. When travelling with a full gray tank, we put the stopper in the sinks and leave some water in the bowl. This seems to work.
The other mystery is the washing machine trap. He will stink at times and of course the solution is run a partial cycle. What I don't understand is why it's smell is emanating from under the kitchen sink?? They are on opposite sides of the room. There is never a smell from around the machine nor for that matter, does the shower drain ever smell.
I have 4 vents on the roof. 1 of course for the black tank, 1 for the gray tank, and 2 for??

I'm missing the plumbing schematic in my owners manual, so I don't know how the vents are tied together. Any ideas?

Ed McManus.....'02 Intrigue......11361

Re: Gray water smell mystery

Reply #1 –
Yahoo Message Number: 72215
We have a 2001 Intrigue with almost identical issues. We have also used plastic bags and rubber bands to cover the vents. Didn't work. ALL of our smells come from under the bathroom vanity. We put water in the vanity as well. We've tried dumping before travel. We've tried traveling with partial or full tanks. We've looked at the washing machine. I've even been on the roof and checked the vent cap. I tried to put a long rod down the vent to see if there was any obstruction but they 'bend' only about 8" down so there's no straight shot at trying to find any blockage. I've seal up the cupboard with a new floor and checked every nook and cranny. Nothing seems to work. The strange thing is that the drawers beside the cupboard share the same space and yet they don't smell!!
Now we only ever get the smell for about the first 20 minutes or so of traveling. And then not always. Has nothing to do with how hot the weather is either. We travel with vents open. We travel with vents closed. We travel with windows open and with windows closed. We simple can't find a common link.
So we've resigned ourselves to the 20 minutes of 'smell' on every second trip as being a part of RVing. And we only travel/move about 5-6 days a month.
If it's of any consolation we have friends with a top of the line Travel Supreme. Their smell is something else and it lasts as long as they are on the road! So it's not just our motorhomes.

Bruce 2001 Intrigue #11278

Re: Gray water smell mystery

Reply #2 –
Yahoo Message Number: 72216
Ed,

You should also have a vacuum valve under the kitchen sink. Took me three years to find out that mine was broken off. Replaced and no more smells.

I also installed the 360 degree vents on the stacks on the roof.

George

'04 Inspire 51061

Re: Gray water smell mystery

Reply #3 –
Yahoo Message Number: 72221
We've only had this issue when we are dry camping for sometime and not running a lot of water through the traps. We have also found that putting a small amount of borax powder, flushed with a small amount of water, into each sink before we travel solves the problem. Borax is a natural substance with many uses according to this web site:
http://www.stain-removal-101.com/borax-powder.html
Ray

2000 Intrigue
#11040

Re: Gray water smell mystery

Reply #4 –
Yahoo Message Number: 72224
Three years ago we had the same problem and I have tried several things, to include changing the top vents, both under-sink vacuum valves, cleaning the tank(s)to squeaky clean and sealing the washer hose drain into the PVC drain pipe. The only two things that made a difference was cleaning the tanks and finally sealing the washer drain hose with plumbers putty. To clean the tanks, I dumped the largest bottle of Dawn dish soap into a half tank of water (both tanks) and drove for a couple hundred miles. Then I rinsed the tanks 4 or 5 times until I saw clear water without any debris draining out of the tank from the clear drain adapter. The cleaning helped tremendously, to maybe a 90% improvement. I think the final solution was to seal the washer drain hose into the PVC drain pipe with plumbers putty. Since I've done that three years ago, we have had zero odors from the grey tank. Some here have cautioned on sealing the washer drain hose because of the added stress it may place on the washer drain pump. I don't know about the validity of this, but it seems to keep out the odors in the coach, so I'll deal with the washer pump when/if it breaks. After camping, I always fill/drain my grey tank a few times until I see clear water draining out. It is surprising to me on how long it take to get clear water to drain from the grey tank.

Larry, 03 Allure, 30856

Re: Gray water smell mystery

Reply #5 –
Yahoo Message Number: 72225
Ed,

A couple of things come to mind. First on the no vent vents, under the sinks, They are pipe thread and I have found on more than one occasion they have been screwed into a sink trap fitting. If so they will leak air, check that. If they are not pipe to pipe replace the fitting with a female adapter. Second It sounds like, from water coming into the sinks when traveling, the vent pipe in the tank extends into the tank several inches. It should be at the top of the tank, not protrude into the tank. Let me know what you find.

Mikee

Re: Gray water smell mystery

Reply #6 –
Yahoo Message Number: 72236
Step #1 is to install RV 360 vents or their ne Siphon vents. I have these and no smells at all even when boondocking in 90F weather.

Rich 2002 Magna

Re: Gray water smell mystery

Reply #7 –
Yahoo Message Number: 72238
Take a look at discussion chain in posts:

69362
20485
11013

Jim Hughes

2000 Allure #30511

Re: Gray water smell mystery

Reply #8 –
Yahoo Message Number: 72240
Ed, there have been several theories advanced about the cause of your graywater smells. All are possibilities. Have you tried chemical deodorizers? Also, I suggest you are not dumping the gray water often enough. I like to dump and then carry a small amount of fresh water in the tank to sort of rinse it out while traveling.
Finally, you asked about 4 vents on the roof. (1) each to the Black water, Gray water, Washer/dryer and Shower. A venturi type vent on each would be helpful against creating positive pressures in the waste tanks.

Good luck,

jim Hodges

2007 Inspire, #51969

Re: Gray water smell mystery -Valve

Reply #9 –
Yahoo Message Number: 72247
George's idea fixed our problem a few years ago - in the bathroom. We also use the Venturi's, but the real fix was the valve/cap on that "vent" pipe that rises under the bathroom sink--It was blown and was not obvious.

Terry A

2004 Allure Newport 40' 31001

Re: Gray water smell mystery

Reply #10 –
Yahoo Message Number: 72251
I too have had an odor issue since day one with this coach and it is extremely frustrating.
I have replaced all of the vents again (3) using Teflon tape to install them, tried a straight through venturi cap on the driver's side roof, various chemicals and cleanings. So far the only thing that works is dumping the tanks every time before traveling. This is a huge inconvenience for me as I travel alone and should have to dump the tanks but once a week or so.
I worked on this last week with Kevin Waite and we took apart the cabinet backs, drawers, panels etc. We examined every pipe we could see and checked to see if they looked glued and to see if any screws or nails had penetrated the pipes to no avail. When I left Kevin my grey was empty and I got an odor from the black. Kevin picked up another venturi but Guaranty RV said we were attacking this from the wrong perspective. They gave him some chemicals called Happy Campers which they claim will solve the problem. Unfortunately I am now parked for 10 days so I don't have an opportunity to test it out.
Maybe we should get together and hire a plumber expert and find out exactly what causes this and what could be done to solve it. It is really annoying that not every coach has this problem, why the difference?
I wanted to try the smoke test but I haven't found anyone that can do it. I tried to buy some peppermint oil in Junction city but no one had it. I bought some smoke bombs but either they don't have enough volume or there were no pipe leaks. It did show however that the vents were working as smoke billowed out of them.
Could it be the Washer? Mine is in the bedroom rear passenger side. The smell seems to come Drivers mid coach. There is never an odor in the washer area or the shower.

John

2007 Inspire 52028