Sailrguy...not sure what kind of problem you are having, but on my Cardinal 32, the black tank is not draining when I pull the valve open. Tried putting back water pressure on the tank, but nothing happened. Need to access the tank from underneath this Labor Day weekend by cutting the sheet metal underneath and removing the insulation to check that the valve is functioning correctly. If it is, then I somehow have to unclog the tank train with a snake.
Dieselguy - thanks for you response, I found that helpful.
C/S 5th - DCC, USN, Ret