Originally Posted by speedmerchant
Just out of curiosity does anyone know what the black water tank flush nozzle looks like? Be curious to know how much coverage it has when spraying.
I tried filling the tank with warm water, letting it sit, and pressuring the nozzle while draining and for two hours afterward. I never really lost all flow through the nozzle, but it is apparent that there is excessive backpressure, which limits the flow. Also, when the hose is removed, about a pint of water flows back out. No change - I think the nozzle just may just have orifices that are too small of a diameter.
I talked to Andy in the parts department about this, and learned that the nozzle has an integral backflow preventer, which I think may be the culprit - it either doesn't open all the way, or in cases of no flow, not at all. I will get a look at a new one (an hopefully photograph it) while in Elkhart for minor warranty work at the end of September.
As I said, I do get about half the flow I should be getting, but I don't think there is enough volumetric or forceful flow to clean the tank walls. I will say that fillling the tank with warm water does a good job of cleaning what I had thought was a clean tank (obviously you need a transparent section of drain tube on the outlet to determine this - I think most RVers already have this).