Sta-Rite Pump Lid O-Ring — 5P4R, DYNA-GLASS (RU9375)

Lid o-ring for Sta-Rite 5P4R, DYNA-GLASS pool pumps. Seals the transparent strainer-basket lid against the pump body under system pressure — the number-one air-leak source on any Sta-Rite pump once it’s a few seasons old.

Replace at the first sign of air bubbles in the pump lid, sluggish prime after backwashing, or when the o-ring looks flattened / cracked / no longer round. Lubricate with silicone grease (never petroleum) before installation — a dry o-ring won’t seat properly and will fail within weeks.