BLACK TANK LEAK

[Lancealot]

How can I tell if the roof vent pipe is properly connected to the top of the black tank? I accidentally left the tank flush on with the handle closed, and water was coming out from the underbelly. What kind of seal is supposed to be there, and how do I see it without removing the tank?

[bw2]

There is a real possibility there is a crack in the black tank. The black tanks are known to crack in the area around the output where the pipe connects to the tank. Since there is water draining from the belly, it would be wise to drop the belly, check the tank and dry the underbelly and ensure the area is "clean". You can run a hose down the vent pipe, leave the valve open and you should have water running out through the sewer hose. Also, you should be able to feel the hose hit the inside of the tank. Good luck.

[DQDick]

Just what bw2 said and while you have some of the underbelly off replace the screws with stainless screws and fender washers.

[pineranch]

Take the easy route first. Check the flush system connections since you did the deed by leaving the system unattended. If all is well, start looking at other connections and last, the dreaded crack.
Mike

[richfaa]

I have become paranoid about holding tank leaks after having had FIVE holding tanks go bad on our 06 3400. We of course never travel with any tank full or even 1/4 full. We keep our Galley tank and black tank closed when on a long stay but dump them every 3 or so days. I feel that just the weight of the contents sitting still and not moving is enough to spring a leak. Every one of them leaked in the same place..at the top at the input to the tanks.