I have a 1960
Overlander with what I thought was the original blackwater tank. It's above the floor on the curb side in the rear bath and appears to be 12 gals or so. I'm now wondering since I can find no information here that is similar to what I have. I need to repair/replace my dump valve which is prompting this thread.
My tank is fiberglass, with a 2" exit pipe glassed into the bottom of the tank. The exit pipe has two threaded ports below the tank for attaching the grey water drains for the shower and kitchen/bath sinks. There is no evidence of hardware or flanges of any type on the bottom of the tank. At the top of the exit pipe, inside the tank, was a concave cap with a rubber seal similar to a flapper valve on a home toilet. The cap had a threaded brass rod running upward from the center, through an approximate 4" round threaded access plate on top of the tank. The handle of the brass rod has tabs that mate with tabs on the top of the access plate. The cam action of these tabs when mated exerts downward pressure on the flapper valve and seals the tank. To dump (from the bathroom inside the trailer), you twist the handle of the brass rod, unmating (is that a word?) the tabs, and pull up. This raises what I am calling the flapper valve from the top of the dump tube and the tank empties.
Is anyone familiar with this type of black tank plumbing and dump valve arrangement? I don't have clearance under the belly pan to add a thetford or valterra gate valve and still tie my greywater lines in below such a valve. I was hoping to find a replacement dump valve or a source for parts. I suppose I could also add a gate valve to the dump tube and plumb a separate dump tube for greywater but that raises other issues. Any ideas short of starting over with a new tank? Thanks in advance.