Mercury 648771 Poppet Diaphragm

Mercury 648771 Poppet Diaphragm

Mercury 648771 is a genuine Mercury poppet diaphragm used in compatible Mercury, Mariner, Verado, and MerCruiser cooling system assemblies where this exact part number is specified by the factory parts diagram.

Key Features

• Genuine Mercury replacement poppet diaphragm
• Used in compatible cooling system pressure relief / poppet valve assemblies
• For select Mercury and Mariner outboard, L6 Verado, and MerCruiser inboard applications where specified
• Direct replacement when Mercury part number 648771 is called out
• Helps support proper cooling system pressure regulation

Fitment / Product Details

• Brand: Mercury
• Part Number: 648771
• Product: Poppet Diaphragm
• Application Range: Select 75-250 HP Mercury and Mariner 2-stroke and 4-stroke outboards, L6 Verado outboards, and various MerCruiser inboard engines
• System: Cooling / Poppet Valve

Poppet diaphragm fitment depends on engine model, serial number, cooling system layout, and the exact poppet valve assembly being serviced. Verify fitment with your Mercury, Mariner, Verado, or MerCruiser serial number and factory parts diagram before ordering.

What’s Included

• Mercury 648771 poppet diaphragm

Poppet valve, spring, cover, gaskets, seals, bolts, thermostats, and related cooling system parts are not included unless listed separately.

Why You Should Buy

The poppet diaphragm is part of the cooling system pressure relief circuit. A worn or damaged diaphragm can contribute to cooling pressure issues, leaks, or inconsistent water flow. Use the correct Mercury diaphragm for the exact engine and parts diagram being serviced.

Common Applications

Used on select 75-250 HP Mercury and Mariner 2-stroke and 4-stroke outboards, L6 Verado outboards, and various MerCruiser inboard engines where the factory parts listing calls for poppet diaphragm 648771.

FAQ

Is this the complete poppet valve kit?

No. This listing is for the poppet diaphragm only.

Does this fit every 75-250 HP Mercury outboard?

No. Fitment varies by engine model, serial number, and cooling system configuration. Verify by parts diagram before ordering.

Can Wakeboss help confirm fitment?

Yes. Send your engine model and serial number through Ask a Parts Pro and we can help check the correct cooling system diagram.