Black Tank Smell

[Turbosix]

Odors from the black tank come in to trailer only when flushing the toilet, not all the time. This is a brand new trailer and our third one and we have never had this problem.

What we have done:
- Used plenty of chemicals per instructions
- Check for vent blockage by smell, used a tape measure to hooked the end and it came up clean with tank about 2/3 full.
- Used the tank flush to stir up the chemicals since it hasn't moved.

What's odd is when I checked for vent blockage there was cool a/c air coming from the vent. I don't understand how that is possible unless the vent isn't sealed at some connection inside the trailer. I would think if that were the case, we would have the smell all the time.

I plan on taking it to a park soon to drain and flush the tank and do more in depth investigation. I was hoping for some suggestions on what I could possibly be. The vent is running up a wall with no access. Is it possible to take one side of the wall off to take a look?

Thanks in advance for the help.

[ScottG]

Deleted - entered in error

[Dennis12]

You need to use odorless poop. Camping world will probably say they have it.

[ScottG]

Bucky Badger wrote:

ScottG wrote:
It's possible (and all too common) that the vent stack is pushed too far down into the black tank.
If it does it more as the tank fills, that is probably the problem.

Many people say this. But isn't the pipe glued? Or isn't it connected to the cap? Reason I ask is how do you push it back through the roof if it indeed slipped down.

All I know is both of the trailers I've owned have been this way.
The sad part is, it would be dangerous to try and pull it upward even if it will move.
If it were to slip out of the top of the tank there's no guaranty you could push it back in.
We have a new TT coming in a week or two and I plan on sending a camera down there before any use. If I find a plug or the vent is jambed in too far, they're going to fix it.

Aperson could always hire a plumber to do the same thing.

[Bucky_Badger]

ScottG wrote:
It's possible (and all too common) that the vent stack is pushed too far down into the black tank.
If it does it more as the tank fills, that is probably the problem.

Many people say this. But isn't the pipe glued? Or isn't it connected to the cap? Reason I ask is how do you push it back through the roof if it indeed slipped down.

[gbopp]

ScottG wrote:
It's possible (and all too common) that the vent stack is pushed too far down into the black tank.
If it does it more as the tank fills, that is probably the problem.

Good advice. Always start with the simple things.

[ScottG]

It's possible (and all too common) that the vent stack is pushed too far down into the black tank.
If it does it more as the tank fills, that is probably the problem.

[Turbosix]

All good advise, thanks. Black tank drain is closed. We are basically boondocking at the in-laws.

I believe the air is coming out of the pipe and not around but will investigate further when I have the time. The A/C duct is cut into the roof foam. I would think if the vent had a crack and access to the ducting that it would smell with the a/c off or once the a/c turned on.

[Old-Biscuit]

A/C ducting in ceiling is leaking.....either because the duct is just a channel cut in styrofoam insulation or flex duct has hole/tear and black tank vent line is NOT completely sealed at roof line.

Unless you are feeling cold A/C blowing OUT of end of vent pipe vs around vent pipe from 'attic area'
Out the end of vent pipe then pipe is cracked somewhere in attic area


Black tank smells when flushing toilet.........not uncommon
All the poop chemical in the world will not stop that'
Toilet is wide open to black tank when flush ball is open'
Exhaust fan on.....smells pulled up
Exhaust fan off.....smells can still come up

You are NOT leaving black tank drain OPEN are you??
Hope not.....liquids run out leaving pile of poop behind.

Dump when tank id FULL so volume/weight of liquids carries the poop out
Always add couple gallons back into tank so bottom stays wet

If not smelling anything other then when flushing ....no big deal