Leaking black waste valve

[Shelane]

1986 casita with a slow (stinky) leak in the black tank. Can't see much from the outside except for residue. Anyone know what the inside looks like, where /how to investigate and fix a leak?

[redbarron55]

Take the four bolts that hold it together off and then put it back together after cleaning and replacing the guts. You can buy a new valve and leave the part attached to the tank side and replace the rest.
Cleaning and greasing with some silicone grease might fix it, but a new seal is a good idea. New valves are not expensive.
By the way the tank should be empty when you remove those 4 bolts...

[Shelane]

Alas, we're pretty sure it's leaking somewhere above the valve, on the tank side...

[redbarron55]

Take it apart anyway and usually these valves are ABS plastic. You can buy ABS glue which is ABS plastic dissolved in acetone, You cans try finding the crack and building up from the inside (after cleaning). If you need thicker goop to make the repair you can grind up some ABS and dissolve it in the glue and mash it in.
On my modified Scamp with a underfloor black tank made from ABS I fitted an ABS fitting onto the side of the tank where I needed it and sealed off the bottom exit.
I also made the 1 1/2" tee that comes off the fitting to the 3" valve for the tie in to the macerating pump I installed. I did the same thing for the gray tank in the rear for the 1 1/2" line to feed the gray tank to the pump. Here is a picture of the added plumbing to the valve to the pump. All of this was done using the ABS glue adding the ground up ABS plastic.




The pump outlet curves through the cabinets to this hose reel to drain the gray and black tanks

Perhaps too much information, but you can fix these things if they are the black ABS fittings usually installed.

[redbarron55]

Also with that slow leak and the tank on top of the floor under the toilet I would bet that the wood in the floor is rotten and the flexing has helped with the crack.
You might want to pull the Sealand toilet and repair or replace the tank and then repair the floor.
Also you can thoroughly clean the tank and take the toilet off and clean the tank and patch it from the inside, using whatever sealant works with your tank.
The hard part is getting resolved to start the job!

[Shelane]

The floor being rotten feels like a safe bet, and I agree that resolving to get started will be tough. As long as ghee leak stays small, I can imagine us justify waiting until we don't have any time constraints!

Thanks for your thoughts.

[Jann Todd]

Originally Posted by Shelane

1986 casita with a slow (stinky) leak in the black tank. Can't see much from the outside except for residue. Anyone know what the inside looks like, where /how to investigate and fix a leak?Attachment 135803

It is these kind of things that are not fixed is why so many campgrounds have a no older than 10 years old rule for RV's. They don't want the smell or the waste on the ground. So please fix it to help all your fellow RV'ers.