odour while driving - traced to black tank

[Mkaye]

2011 Coachman Freelander
it started 2 years ago 1/2 thru our newfoundland/labrador trip (lots of rough roads)
we were in Gros Morne and started smelling something as we went up & down the hills
we emptied our tanks & it seemed better
i put a venturi cap on the black stack
not much travelling last year
this year much worse, especially on hills
the smell would come & go

thought it might be propane, turned propane off, but odour still there

on our drive home yesterday I had my wife driving and i started checking
i opened the roof vent above the driver's seats to draw anything forward
i finally traced the origin to the furnace grill below the wardrobe
this is a large space with the furnace & water heater & a couple of drawers
i pulled the drawers and as we went over a slight bump a cloud of odour hit me
the black tank vent pipe is in the back left corner of this space - it goes through a corner cutout and down to the tank
i can't see the connection to the tank
i am assuming the problem must be at the connection to the tank & that up/down hills, decelerating etc causes the waste in the tank to slosh around and open/close the break
i checked the tank underneath last year & everything looks secure

how do i tackle this?
how is the pipe connected to the tank?
do i need to drop the tank?
or something like spray some foam around it & hope i get it?

mark

[Ljwt330]

Originally Posted by Mkaye

2011 Coachman Freelander
it started 2 years ago 1/2 thru our newfoundland/labrador trip (lots of rough roads)
we were in Gros Morne and started smelling something as we went up & down the hills
we emptied our tanks & it seemed better
i put a venturi cap on the black stack
not much travelling last year
this year much worse, especially on hills
the smell would come & go

thought it might be propane, turned propane off, but odour still there

on our drive home yesterday I had my wife driving and i started checking
i opened the roof vent above the driver's seats to draw anything forward
i finally traced the origin to the furnace grill below the wardrobe
this is a large space with the furnace & water heater & a couple of drawers
i pulled the drawers and as we went over a slight bump a cloud of odour hit me
the black tank vent pipe is in the back left corner of this space - it goes through a corner cutout and down to the tank
i can't see the connection to the tank
i am assuming the problem must be at the connection to the tank & that up/down hills, decelerating etc causes the waste in the tank to slosh around and open/close the break
i checked the tank underneath last year & everything looks secure

how do i tackle this?
how is the pipe connected to the tank?
do i need to drop the tank?
or something like spray some foam around it & hope i get it?

mark

If this was my situation, the first attempt would be to see if there is any access to the tank/vent/entry port connections. I don't know your coach so I am unaware if you can access the tank in any practical way. If not, then my second choice would be to use spray foam and seal the cut-out so no air/odor can enter the living area. The foam will also give some stability to the pipe that penetrates the floor, possibly reducing the vibrations that may have caused a crack or opening in the venting.

[RKins]

Grey tank odors are as bad or worse than a maintained black tank. If your rig is plumbed for a washer/dryer check to make sure that the drain for the washer has water in it (p-trap) otherwise the grey tank odors are being sucked back into the coach via that pipe.

[scbwr]

Have you replaced the inline vent? Here's a listing for one at Amazon:
https://www.amazon.com/Oatey-39012-A...86&s=hi&sr=1-6

When the flapper in these vents start failing, you will get sewer gas. It was happening in our bathroom. After installing a new vent, the problem was gone and all you have to do is unscrew the existing vent and screw in a new one. They're cheap enough that you can go ahead and do it under the kitchen sink and wherever else you have plumbing lines with a vent.

[Mkaye]

yes, i checked the vents - only 2 under the sinks
found the bathroom vent glued closed from factory - replaced last year
made sure all p-traps had water
i'm sure it is black tank as the vent is in the space where the odour originates

mark