Pentair FNS filter - Hi-flow valve leaking out to backwash

[naztuk]

I have a Pentair FNS filter with a Hi-flow backwash valve. The valve top was cracked around the bolt holes and leaking so I replaced the valve top and the gasket. I adhesived the gasket in place and replaced the valve top. Now there is water leaking out of the backwash hose when the valve is set in filter mode. Everything seems to be installed correctly. The gasket matches the original one and the valve top is the correct one and the same as the one replaced. Any ideas on what is causing this and how to fix it? Thanks

[Poconos]

Welcome to the forum. Not familiar with that specific valve but it sounds like a multiport from your description. If it is then a couple things I would suspect are internal cracks and/or possibly low spring pressure. I seriously doubt the spring but something to consider. If it is weak the water pressure could cause the part operated by the handle to lift off the gasket. If you didn't already, I'd take it apart again and be sure the gasket didn't lift off someplace and get a light and look in all the passages for cracks. Not much else that can go wrong.Keep us informed. Anyone else with ideas?
Al

[waste]

Welcome to the Forum!

Al's got it covered

Please keep us informed!