663-44315-A0 Yamaha gasket | Genuine OEM Yamaha Outboard Part

🔧 Product Description

Genuine Yamaha Water Pump Wear Plate Gasket - Part Number: 663-44315-A0

A genuine Yamaha lower water-pump gasket fitted beneath the wear plate on selected 40HP and 50HP two-stroke outboards.

The gasket seals the lower face of the stainless pump plate against the gearcase or pump base, preventing cooling-water pressure from escaping beneath the impeller assembly.

⚙️ Key Features

• Genuine Yamaha OEM water-pump gasket
• Correct Yamaha part number 663-44315-A0
• Lower wear-plate sealing position
• Used in selected Yamaha 40HP and 50HP two-stroke pumps
• Cross-references with Sierra and Recmar replacements

🚤 Compatibility

Commonly used on

• Yamaha 40HP and 50HP two-stroke lower-unit water pumps
• Pump assemblies using the 663-series wear plate and cartridge components

Typically suits

• Engine models:
• Yamaha 40HP two-stroke - approximately 1984-1994
• Yamaha 40E, 40H, 40J, 40N, 40Q and related 663-series gearcases
• Yamaha 50HP two-stroke - approximately 1984-1987
• Yamaha 50HP Pro Series - approximately 1987-1990
• Yamaha P50 - approximately 1995-1996
• Yamaha 50D, 50G and 50H lower units using the 663-series water pump
• HP Range: 40HP - 50HP
• Engine Type: Yamaha carburetted two-stroke outboard
• Year Range: Approximately 1984 - 1996, dependent on gearcase

🔌 Function

The gasket seals beneath the water-pump wear plate so cooling water is drawn through the inlet and directed into the pump without bypassing the impeller chamber.

⚠️ Common Signs of Failure

• Weak cooling-water flow after water-pump service
• Engine overheating despite a serviceable impeller
• Water leaks beneath the wear plate
• Gasket tears during pump disassembly
• Corrosion or old gasket material prevents the plate from sitting flat

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 663-44315-A0 current Yamaha OEM water-pump gasket reference

OEM / Related Numbers

• 663-44315-A0
• 663-44315-A0-00
• 66344315A000
• 663-44316-A0 related upper wear-plate gasket
• 663-44322-00 related pump insert
• 663-44323-00 related water-pump outer plate
• 663-44324-A0 related cartridge gasket
• 663-W0078-00 related water-pump repair kit

Aftermarket / Verified Equivalents

• Sierra: 18-0292
• Recmar: REC663-44315-A0
• Included in Sierra lower-unit seal kit 18-2789
• Included in Sierra water-pump kit 18-3430

📦 Condition

• Genuine Yamaha part
• Brand new
• Supplied in original or equivalent packaging