Re: Bilge Pump Check Valve Issues on 2013 Beneteau Oceanis 45
Check valves are often installed in bilge discharge hoses when a large pump is put in a small bilge.
The discharge hose holds water after the pump stops and it flows back into the bilge.
With a large enough hose and a small enough bilge the back flow can cause the pump to turn back on and cycle on and off.
The check valve is an attempt to stop the back flow. It rarely works as the check valves leak. It slows the cycle but doesn't stop it.
A better way to deal with it is to install a smaller pump with a smaller hose that won't hold enough water to cycle the pump. Keep the bigger pump but mount it's switch a little higher than the small pumps switch. With luck the big pump will never turn on but it's there if you need it.