Black tank overflow in 2020 T@B400

grsiepka

Past weekend camping trip. Buttoning up things ready to leave the campsite. Black tank was reporting 2/3 full. Still had a good amount of fresh water left so I thought to add some water to the toilet to help things flow easier when we get to the dump site. 

We must have been on the extreme high side of 2/3 and somehow overfilled the black tank. What we saw was a stinky puddle of water that came out under the front dinette cubby and onto the floor in front of the driver side dinette seat. Some frantic cleanup ensued and followed by a white knuckle drive to the dump station hoping for no more spillage. 

So now this begs the question..  What the heck happened?  How did black tank water get onto the floor and not spill into the shower pan area in the bathroom? Does anyone know what the setup is there? Is there some type of vent under the dinette seat cubby that the water came out of into the cabin area? 

ScottG

I'm not specifically knowledgeable of the drain layout in the 400, but I would expect the black tank to overflow by simply rising up in the toilet (and--as you suggested, ultimately spilling over into the shower pan where it would go down the drain to the grey tank.

The black tank should be vented, but any vents should be well above a level that would risk any overflow.

Makes me wonder if there isn't a leak somewhere--either a crack in the tank itself  or (more likely) the joint where the vent attaches to the tank.

grsiepka

Yeah that is my worst fear is a cracked pipe leading to the vent thru the roof. This is something I'm probably going to need to tear into myself today as I can't really wait the 6-8 weeks for a dealer visit. 

N7SHG_Ham

How did you add the water to the toilet? If down the toilet, you should be able to see the tank level, it drops straight into tank.

ScottG

grsiepka said:

Yeah that is my worst fear is a cracked pipe leading to the vent thru the roof. This is something I'm probably going to need to tear into myself today as I can't really wait the 6-8 weeks for a dealer visit. 

Good luck! Take and post lots of photos.

grsiepka

N7SHG_Ham said:

How did you add the water to the toilet? If down the toilet, you should be able to see the tank level, it drops straight into tank.

Yep, stepped on the flush lever for a minute or 2. Could see the water level but kinda hard to judge looking down into a dark smelly hole. It definitely didn't appear that it was close to coming up the toilet hole though. 

Denny16

First, the black tank in a TaB400 is above the floor of the camper.  There is a vent pipe connected to it which runs up behind the sink panel.  The only openings to the tank are the toilet mount (obviously) the flush out connection (which is also behind sink) and the vent pipe, none of these are anywhere near the inside wall.  Here is a photo showing the black tank and gray tank vents.  The black tank vent is the one indicated by the red arrow:

Another thought, the black tank is under the shower pan and the white cover under  the white cover the pipes go through.  The top of the black tank under this front area under the sink, is lower than the top of the tank under the toilet, a bad vent pipe connection to the tank ir a crack in the pipe below the cover, but above the tank, would leak down and under the shower pan, and into the dinette when the front is lower, especially during towing when everything sloshes around.

You can check the area under the shower pan, by removing the vent cover under the washroom door.  You can get a flashlight and see if it is or has been wet under there.

Did you drive to the dump point and then discover the mess?  If so, it could also just have leaked out from the toilet to tank seal, and if the front of your TaB is lower in the front when hitched, the black water would have seeped out along the front inside divider and down to the floor.  Try pouring some water down along the back of the toilet and see where it goes.  If it seeps back into the dinette then you have your answer.   Also check he toilet to tank seal to check if the screws loose, if so, this is properly your leak, as water could seep out here from an overfilled tank.

If the water ends up on the dinette floor, I would recommend a good disinfectant, and pour it down along the back of your toilet to really clean down in and behind every where the black water seeped in and the dinette floor, and front of the bench seat cabinet area. 

You could also just call nüCamp service and ask them for a suggestion or cause?  If the top of your black tank is cracked, you could possibly have a warranty issue.
cheers