Today I spent 4 hours messing with the Power Air Dump Valve on my Wanderlodge. These are awesome when the work, but no fun when they don't, My gray water valve was making very nasty sounds and not wanting to close fully. Here's what they look like:

Basically, air pressure slides a plunger up and down. The bottom slide had a rubber sealing membrane that was the culprit on mine. It was all chewed up and not sealing or sliding very well. Fortunately, Dupree Products still makes these and all the new parts I needed were shipped in three days.

On the WL, the black water valve is up front and mounted vertically with lots of room to slide the innards out. Not so with the gray water valve. It is mounted horizontally and way back. To make matters worse, there is not enough room to get the assembly slid out before bumping into the steel wall in front of the tire well. My remedy was to unscrew the handle, then drill a 1/2 hole to slide the rod out to make it removable. Turns out with further research this is what all the pros do too.

The installation of the new slide gate and seal was very quick and easy. Just unscrew the old and screw on the new. Lots of silicone grease and that baby actuates like its new! I have another repair set coming to do the black water side, which should take less than 30 mins due to accessibility and experience.

If you're looking for a neat upgrade, the valves are only $150 new complete. Pretty decent value for what you get. Remember you need compressed air too though.