Quicksilver 648771 Poppet Valve Diaphragm for Mercury & Mariner Outboards and MerCruiser Engines

The Quicksilver 648771 Poppet Valve Diaphragm is a genuine OEM replacement part designed to keep your engine's cooling system operating correctly. The poppet valve diaphragm regulates cooling water flow and pressure through the engine — a critical function for preventing overheating and maintaining long-term engine health. When this diaphragm wears out or cracks, symptoms can include fluctuating water pressure or an engine that runs hotter than normal.

Manufactured to Mercury Marine's original equipment specifications, this Quicksilver part ensures a precise fit and reliable performance. It is constructed from flexible, marine-grade rubber engineered to withstand heat, saltwater exposure, and continuous pressure cycling.

Key Features:

• Genuine Quicksilver OEM replacement poppet valve diaphragm
• Compatible with select 75–250hp Mercury and Mariner 2-stroke and 4-stroke outboards
• Fits L6 Verado outboards and various MerCruiser sterndrive and inboard engines
• Molded to factory specifications for proper sealing and water flow
• Serviceable with common shop tools
• Poppet valve diaphragm only — additional parts required for full service are sold separately

Quicksilver parts are produced to match Mercury Marine's stringent OEM performance standards, ensuring the same dependable cooling and protection your engine had from the factory. Consult your owner's manual or service manual for specific application information and installation instructions.