I thought this might be of interest to those who have had or might yet have a plugged outlet on the black water tank as I had.
While I don't know the reason (possibly not putting enough water in the tank the last time it was emptied or a gate valve not fully seated...whatever), but once it has happened, the reason doesn't matter. I have been at a Resort in Arizona the last 2+ months, but this time when I emptied (tried to) the tank, it suddenly stopped draining after the first surge. Somehow the solids must have rushed to the outlet of the tank and plugged it almost completely. My first try was to fill the tank completely to give more pressure....nope...still plugged, but now FULL! Time to contemplate after a few *&$%&&$, etc. Thought about calling a sewer pumper to "suck" it out...didn't want to spend the $,and didn't want to apply that much vacuum pressure to the system. Use a snake? NO WAY....unless as a last resort..since I would be shoving the snake up from the outlet. My next though was...backflush...but how?? Maybe by using the litte garden hose connector on the outlet cap, but again...what about catching the &$**?
Finally I went to an RV supply place and found a connector that incorporated the combination of a clear piece, a flush connection, then finally a gate valve just where the sewer hose connected. By attaching that...then backflushing...(keeping the end gate valve closed and also the gate valve at the tank closed, I ran water under about 65lb pressure into the pipe...forcing a bubble of air up the pipe....kept the water running to build up a good pressure, then pulled the gate valve at the tank...so the air bubble would force the solids from the outlet) To shorted the story, it worked to dislodge it temporarily and let some out, then plugged again. It took several repeats of the process, but finally ALL came loose! A simple solution to what could have been either messy or expensive. $35.00 for the drain addition instead of $100 plus for a pumper that could have damaged the system.
I found several other parts similar,but without the gate at the very end. For those interested, this item is made by CAMCO RV, "DualFlush Pro Revers Flush Valve" model number 39062. It can be seen in the following link:
http://www.camco.net/Menu.cfm?SupCat...ProductId=2053
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