Black tank odor

about 2 years ago I posted a long stinky toilet story on this forum and just tried to find it and post a link here but had no luck.

Not going into a long story this time I will give you a brief RE my stinky toilet, its problem, and my fix ( my problem sounds very similar to yours )

I spent a month trying to get rid of a nasty toilet smell, it would go away after I dumped and cleaned the black tank only to return in
a day or so, I did everything I could, different chemicals, replaced the flange seal, then replaced the whole toilet,but back came the smell so I just drained and flushed the black tank every 2 days while on our trip.
When we got back to my Daughters where we store the Fithwheel and Eve got on the airplane and went home I attacked the problem full on.
first thing I did was to climb up on the roof and remove the vent roof seal plastic cap thing and when I did the 1 1/2" abs vent pipe shot up in the air about 2". Not wanting to drop the Black tank
I cut a 8" 10" hole in the paneling behind the toilet at floor level to take a look and sure enough the vent pipe was out of the tank and just sitting on the 2X2 floor joist. The collar hole in the Black tank was there about 4 " over, it was open to the wall space and the odor was there for sure.
On my trailer ( a Jayco ) they do not glue the vent pipe into the black tank vent collar ( I guess it is so the black tank could be dropped down if needed ?? ) The vent pipe had been improperly installed at a ****eyed angle so it could not be fully insert into the collar anyway ( guess the skilled Amish at Jayco put the roof hole about 4" over to far for proper alignment ?)
I heated the pipe a bit with a heat gun and bent it enough to fit down snug into the collar then filled the wall void around the pipe with a can of spray foam to keep it in place then Gorilla glued the cut out wall section back in place.
It has been now 2 years with no odor problem.

I have no idea if this is your problem but it is something to look for.

Aloha from Kauai
Leon

Are you running the exhaust fan when showering? Does the bathroom sink drain to the black tank? Some do.

If so, could be no water in p-trap or maybe bad air admittance valve for the sink?

My guess is bad toilet valve, gray and black tank are not connected.

LakeN wrote:
If you have never kept water in your toilet bowl, it is possible you don't have a seal. Have had a TT where manuf. failed to install the seal!! Thetford said it wasn't possible but it did happen.

No seal? Wow...that's different.

Dtaylor wrote:

Old-Biscuit wrote:

GMandJM wrote:
Are you running an exhaust fan while you're in the shower? Is the toilet near by with the lid open, perhaps?

Water in toilet bowl then toilet floor flange is not sealing.

OR vent fan is blowing in and sucking fumes from black tank vent


Same should happen whether using shower or not.......vent fan running/fumes happen

Fan is running while in the shower. Have not thought about water in bowl. Fan running alone does not produce odor. Might need to check that part. How do you check the floor flange?

Easier to check the other possibilities first.

1) Is the flapper/seal in the toilet allowing water to stay in the toilet? (If not, bad seal or not-fully-closing flapper = bad smells.)

2) Has the "pipe" area under the flapper been de-gunked lately? ("stuff" tends to accumulate there).

3) Make sure your exhaust fan is blowing OUT and not in. (Depending on where your black tank vent is on the roof, having it "innie" could mean you are sucking in the black tank's fumes. (Not fun)

4) Find out if you've got one of those "special" campers where the bathroom sink really does empty into the black tank. (Some people claim to have them; dunno which brands/models though.)

5) Keep in mind that if you're using FHU and your tank valves are left open, you are pretty much turning your entire camper into a vent for the park's sewer system. (Your mileage may vary on that and opinions differ, of course.)

99.8) If you're seeing indications of the flange having gone bad (mushy floor in that area, water marks underneath, other odd things), then you might have to take up the toilet to look at the flange. There are videos on YouTube you can look at to see if you really want to go that route.

If you have never kept water in your toilet bowl, it is possible you don't have a seal. Have had a TT where manuf. failed to install the seal!! Thetford said it wasn't possible but it did happen.

FWIW, always keep an inch or so of water in that toilet bowl to keep the seal alive and to know if your losing water out of the toilet.

Bested by The Biscuit once again in the RV version of "What's That Smell!"

Yeah, I should have asked if there was actually water in the toilet bowl. If not, a leaky seal would have been my guess.

Old-Biscuit wrote:

GMandJM wrote:
Are you running an exhaust fan while you're in the shower? Is the toilet near by with the lid open, perhaps?

Water in toilet bowl then toilet floor flange is not sealing.

OR vent fan is blowing in and sucking fumes from black tank vent


Same should happen whether using shower or not.......vent fan running/fumes happen

Fan is running while in the shower. Have not thought about water in bowl. Fan running alone does not produce odor. Might need to check that part. How do you check the floor flange?

GMandJM wrote:
Are you running an exhaust fan while you're in the shower? Is the toilet near by with the lid open, perhaps?

Water in toilet bowl then toilet floor flange is not sealing.

OR vent fan is blowing in and sucking fumes from black tank vent


Same should happen whether using shower or not.......vent fan running/fumes happen