There are 2 kinds of 'manual dump valves'. The kind installed by Cruiser at the factory is the worst kind. Those valves are attached to a very long cable (about 8 ft. if I remember correctly). All of that cable length introduces way too much friction which all but guarantees failure eventually. And the actual valve itself can become stuck even if the cable is moving properly. I had to replace my black valve shortly after taking delivery. The replacement was brand new and identical to the original. The new valve was stuck tight about 20% open in only a couple of weeks. Working on these valves is a nasty job-cut away enough underbelly fabric for access and then have poop gushing into one's face as the valve is replaced.Then attempt to replace the underbelly again. This time, my replacement valve is a 12vdc electric valve. It has been working flawlessly for the last one year plus. I also added a manual black valve which is placed directly inboard of the drain cap. This second valve will really be appreciated if your main valve fails and will save your shoes from being dumped on with poop at the dump station.
The other type of manual black dump valve provided by some manufacturers is not found under the underbelly fabric fortunately. It is similar to my second valve (see above) in that it is found just inboard of the dump cap. I had one of these valves on my Sprinter TT.
If my present electric valve ever fails, I will make sure that it is stuck in the open position and from that point on just use my second valve just inside the dump cap.........just like Sprinter owners do from the get-go.
My electric black valve is a Valterra Electric EZ Valve
