I have a Hayward 3-way valve which is leaking in one of the positions.
One input to the valve is just after the pump, one goes to the filter and the other goes to discharge water when the pool is too full. When the discharge side is closed, I get a small amount of water dripping through the discharge hose and when I put the pump on high, naturally, the dripping gets much faster.
I disassembled the valve looking for damage inside and found it to be OK. I lubed the o-ring and the gasket around the "gate", checked the inside of the valve body for something that might not belong there and reassembled. Still dripped at about the same rate.
I figured "maybe something is wrong with the gate part". Since I have 2 other of the same valves in a couple of other places, I just swapped out parts between 2 of them to see if the situation improved in an effort to see if the problem was with the gate part or the valve body. I made the swap, and same thing. Drip, drip, drip... To me I have ID'ed the problem as being the valve body, but that just does not make sense to me. How could something happen to the inside of the valve body to cause an incomplete seal?