Sewage smell going up hills

[Dunner]

First trip since I got my MH and on the way home, when I went up Telegraph Pass east of Yuma and Mohawk Pass a little further, I had a strong sewage smell. Black tank showed 1/3 full, Grey 2/3 full. I know I could get a Cyclone vent, but what would cause it to smell only when going up a hill? I got down to 45 MPH on the 6% grade, but didn't lose much speed on the Mohawk hill. No smell when I got in stop and go city traffic. No smell on the way there, but the black tank was empty.

[RV Wizard]

We have found that the motion of the coach can cause the water in "P" traps to flow out enough to cause the gases in the tanks to escape into the coach. The wife will get up and add water to all the drains and the odor goes away. For us it only happens once in awhile; under the right angle and turn radius.

[Dunner]

Funny you should mention that. I made sure the traps had water in them before I parted camp. The bad part is that the smell lasted about 10 miles, even with the driver side window open and the air on vent.

[Dunner]

If the water drained out of the traps on the 6% hill, wouldn't the smell still be there on level ground?

[njs42]

One thought: if you have washer/dryer? It could be that P-trap---and it has an interior vent pipe.

Our w/d was the source of sewer odors until we found the drain hose was inserted too far into the drain pipe---past the p-trap.

A window open in front can cause rear odors to move forward because of changing air pressure.

[Dunner]

No W/D. I RV solo, so don't have anyone to check where the smell is coming from. I've heard that RVs have lightly sprung vacuum breakers on the sinks. I guess I could try some silicone grease on them to see if it still does it. I can't remember if I put chemicals in the black tank.

[njs42]

Dunner---The grey tank gives off a nasty sewer smell--the only sewer smell problem we have had is from the grey tan. Black tank/toilet---grey tank every thing else shower/sinks so more places for the smell to come from.

Could you have had a roof vent open? If so opening the front window can cause air to dive off the roof and into the coach.

And, of course the biggest question? What are we doing up so early in the morning???

[Dunner]

Insomnia. Eyes are starting to slam shut, though.

I might have had my Fantastic vent slightly open. I'll try chemicals in both and if that doesn't work, in both before the trip home.

But, why only up a hill?

[njs42]

I was trying to think of that myself. It would shift the source of odor, by 6% anyway, and it might change the airflow over the roof enough to allow the vent to open. Different angle for the wind over the roof????

If your fantastic was open a little---dollars to doughnuts that is the entry point. Make sure it is closed and problem solved I'll bet.

The chemicals in the tanks will not help much---but flush the tanks out really well anyway. Particularly the grey--it is really foul (all of them are).

Best I can do at this hour.

Now that is all I am going to think about when I get back in bed??????

[njs42]

Also a different angle to the wind and slower speed could create a venturi effect and allow the vent to draw air in---where as other wise the air just blows back off the roof.????

[bldrbob]

We found that the shower trap would allow fumes in so we place a ziplock bag of water over drain when traveling and no smells.

[Dunner]

Pretty sure I turned the Fantastic off before I left for home, which would automatically close it. The two tank vents are 5 and 8' to the rear of the Fantastic. I'm not arguing, just trying to logically think this out. With any air flow over the top of the Fantastic it would create suction from the MH. If it was open, it could swirl around and come in.

The second hill is so little of a grade, it doesn't even have a % sign.

I can't drain the tanks before I come home, but I did before the trip. I have a spray system for the black and the water was coming out pretty clean. No smell at all on the hills on the way down.

njs42, glad to give you sweet dreams.

My Non-LX Breeze came with a tub/shower; sorry LX owners. I could close the drain next time.

[bldrbob]

If you had enough water in the grey tank that when you went up hill the water moved to one end of the tank If the shower drain pipe is near that end water would move into the shower pan and smell. When you stopped level the water would drain back into the tank.Place a dry paper towel in shower and go up a hill. If the towel gets wet mystry solved. If it is still dry keep looking.
BOB

[Dunner]

If that is the case, I have a spare water pump plumbed from the grey to the black tank. If I ever fill the grey tank, I can pump some of the grey to the black if needed.