Black Water Tank Odor

rogo88 · 09-20-2014, 06:18 PM

I hope that someone can aim me a helpful direction.

A new conundrum for our 04 Journey 39W
When parked, everything works up to spec.
As soon as we start travelling at speed, we are subjected to a black water tank odor. Over time, it gradually diminishes, but does not always disappear completely.
The odor is emanating from the area behind the cabinet which is prepped for a washer/drier. I have removed the back panel of this cabinet. All pre-piping for addition of a washer/drier appears to be in good, originally installed shape. The odor is strongest at the bottom of this area, but I figure that it would be, regardless of the source of the gas leak since it would be heavier than air. Black tank vent, itself, is clear and everything visible behind the narrow cabinet housing the water connections appears to be in good shape.

Access to the black tank vent piping seems to be limited, but I've inspected all that I can.

Anyone have any suggestions? Strange that "at rest" all is well, but under way this problem occurs.

Thanks,
Ron

Bumps · 09-20-2014, 06:35 PM

Is the drain pipe that is prepped for the washer capped-off? If not, is there a p-trap? If a p-trap, is there water in it? (There should be). You may need to pour a couple cups of water (or red-stuff-antifreeze, this time of the year) down there. That drain pipe is a straight shot to the grey tank -- a cap or a p-trap with water will block the fumes. \ken

lajuene · 09-21-2014, 08:18 AM

It sounds like you are talking about the gray tank if it's under the washer/dryer area. I think the gray smells worse than the black anyway. if there is a standpipe and you don't have a washer installed then you should cap it off. Then there would be no place for the oder to come in.

mel s · 09-21-2014, 08:59 AM

Quote:

Originally Posted by rogo88

A new conundrum for our 04 Journey 39W
When parked, everything works up to spec.
As soon as we start traveling at speed, we are subjected to a black water tank odor. Over time, it gradually diminishes, but does not always disappear completely.
The odor is emanating from the area behind the cabinet which is prepped for a washer/drier.
Anyone have any suggestions? Strange that "at rest" all is well, but under way this problem occurs.
Thanks,
Ron

Ron
I believe you are "sniffing up the wrong tank".

Few washer drains (if any??), are plumbed into the black tank.....(in most RVs the "washer drain" is plumbed into the gray tank).

As has been suggested make sure the washer drain p-trap has water, (or RV anti-freeze), in it.
If it is dry, (and IF your washer standpipe is plumbed to either waste tank), any "negative pressure" in the RV cabin, (created by driving with windows and/or roof vents open while driving... and by running a vent fan when stopped), can and will draw "tank odor" into the RV.

BTW, in some RVs , (like my Safari), the washer does not drain into either waste tank.... (it flows directly out the 3" sewer hose connector).

Mel
'96 Safari

rogo88 · 09-21-2014, 11:02 AM

I thank you all for your responses.

I believe the washer prep piping is intact as it should be and capped. I'm pretty sure that the odor is coming from the black tank. I figured that the washer prep piping has to have a vent and that it was connected to the common roof vent serving both black and grey water systems. So I thot' there was a vent interconnection somewhere allowing the black water odor to back up into the washer piping.

Would be nice if things were a bit more accessible.

Thanks again,
Ron

skigramp · 09-21-2014, 12:17 PM

I have the same rig ... is the odor worse on those occasions where you dump just before you get underway?

If I don't flush my sewer hose thoroughly ... I get an odor coming up into the bathroom area after dumping and stowing

Just a thought

Tom-NC · 09-21-2014, 02:05 PM

Hi,

Do you leave water in your toilet bowl to keep gasket there moist and make a good seal?

Do you leave your roof vent open that is near to the vent stack for the black tank? Is the smell coming from the vent on the roof when you are traveling?

Where are you stowing your sewer hose? I stow mine in a 4" pipe that I mounted outside under the coach.

Hope this helps.

Retiredx2 · 09-22-2014, 04:45 PM

We have had the same issue with incredible odor coming from our 2014 Itasca- come to find out when this coach was made there was no p- trap installed under shower- as there is no room to install a regular p- trap now-- Winnebago has told CW to install a waterless p-trap---once again we are in the shop....

mx08453 · 09-22-2014, 05:40 PM

I had odor in coach that drove DW crazy.
At each sink and behind the washer/dryer are some vent caps mounted quite high in the space.
The valves fail and odor escapes. Mine are on the Grey tank .
Some folks say Grey tank odors seem worse than black
Search home depot for link below.
Recommend replacing all of them. You will be a hero. Good Luck! Price is reasonable.

http://www.homedepot.com/p/Oatey-1-1...9012/100204205

Best wishes

Tom-NC · 09-22-2014, 06:54 PM

The last 2 posts have to do with grey water tank and not black water tank as originally asked about.

I have a 2014 Adventurer and there is a p trap under my shower so can't understand why there isn't one on yours.

The vents under the sink seldom go bad however if they were bad they probably wouldn't open thereby the water in the sinks would not go down unless they are stuck open.

If I had the cash I would go for the waterless traps but I bet they would malfunction at one time or another.

Lets hope that we are on the same page and the problem is with the black tank and not the grey tank.

mx08453 · 09-22-2014, 09:02 PM

Sorry, I understand that you feel it is black water. My point is that Grey smells nearly as bad as black and there are many more opportunities for the Grey smell to get in the cabin, expecially in the area you are talking about.
A bad cheater valve will not likely slow drains.

A search of the forums, will yield many comments about similar complaints.

I found mine by opening the vanity doors below the sink and sniffing the air. Also had a bad one under the kitchen sink and later smell came out of the washer dryer cabinet area. I have a Itasca, but a RV buddy had similar experience in Allegro coach. Happy hunting. ....

mx08453 · 09-22-2014, 09:18 PM

Here is a link to recent posts,,,, http://www.irv2.com/forums/showthread.php?t=220580

mel s · 09-23-2014, 09:44 AM

Quote:

Originally Posted by mx08453

Sorry, I understand that you feel it is black water. My point is that Grey smells nearly as bad as black and there are many more opportunities for the Grey smell to get in the cabin, especially in the area you are talking about.
A bad cheater valve will not likely slow drains.

mx08453

I agree that "grey smells nearly as bad as black"... and that a bad air admittance valve: (aka: cheater valve):

which are often the source of a "tank odor", WILL NOT likely slow drains"...(unless it "fails" in the closed position).

If/when an air admittance valve fails to close, (does not seal properly), it WILL allow tank odor into the coach.

One key to locating and stopping "tank odors" in a RV is understanding HOW air admittance valves work, (if your RV has them..NOT ALL RVs do!), and WHY they are used.
See: Air Admittance Valves explained

Mel
'96 Safari