We are having some issues with the kitchen sink drains. 2019…

Make sure you do not have another grey tank valve. Many Forest River 5th wheels have another drain valve and that can be located over the tires, some models the slide room needs to be out to access the valve. IF you can not find it I would call a Forest River dealer in your area to see if there is another location. Also make sure the vent pipe on the roof is clear, sometimes leaves or birds can make nests under the vent cap and block the pipe off, the tank needs to vent properly in order to drain.

Robert

Normally you would have two valves near each other which is the black water and grey water, then away from them you would have that second grey water valve, not many owners not about the second valve.

You could have a faulty valve as well, I would run something up the discharge pipe and then open the valve and ensure it goes further up the pipe.

The valve is held together by 4 bolts since it is the grey water and not black water I might gain access to the valve and loosen it and see if water starts to come out, if so the valve is faulty.

Robert

You have tried and looked at everything I would suggest on this. Normally snaking would clear the pipe but I do not want you to damage anything as well. The only other thing I can think of to try is to block the vent pipe on the roof and then try a shop vac on the pipe to see if you can get the blockage to dislodge, I might also try some baking soda, vinegar and hot water down the pipe or drain as well.

Might need a RV mobile tech to come out and have a look at this for you.

Robert

No problem at all.

Have a good day, Robert