I also bought the "valve". What I found was, there was little to no "slope" on the long pipe from my kitchen gray water tank to the main 4" sewer valve. One of the brackets holding the long pipe was too low and the drain pipe had a slight downward bend that held about a quart of water. I re-positioned the bracket, added "slope", and now the tank drains just fine.
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2017 29RKS
2018 Ford F-250 Lariat, 4X4, 6.7L PSD, SC, SB
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