GHmarine water pump impeller kit for Yamaha 115–300 HP — 61A-W0078 direct-fit rebuild with housing & gaskets

GHmarine's 61A-W0078 water pump impeller kit is a complete replacement assembly engineered to restore reliable cooling flow for Yamaha 115–300 HP V4 and V6 2-/4-stroke outboard engines.

When an outboard begins to overheat or shows reduced water discharge, the culprit is often a worn impeller or a compromised pump housing. This GHmarine kit includes the impeller, housing, wear plate, gaskets, fasteners, and small parts needed to rebuild the pump and get cooling performance back to factory-style operation. It’s designed as a direct-fit aftermarket replacement for common Yamaha part numbers and several third-party equivalents, so mechanics and DIYers can swap components without extensive modifications.

What engines and part numbers does this kit fit?

This impeller kit covers a wide range of Yamaha outboards from 115 through 300 horsepower in both V4 and V6 configurations, for 2-stroke and 4-stroke models. It is intended to match the dimensions and function of several OEM and aftermarket references so you can replace failed pump assemblies with confidence.

• Compatible with Yamaha 115, 150, 175, 200, 225, 250, 300 HP engines
• Works on V4 and V6 2-stroke and 4-stroke outboards
• Cross-references OEM: 61A-W0078-A2-00, A3-00, A4-00 and related numbers
• Also replaces Sierra 18-3396-1, Mallory 9-48618 equivalents

Which components are included and why they matter?

The kit supplies all the small parts commonly damaged or lost during pump failure, eliminating the need to source separate pieces. Each component is chosen to restore sealing, alignment, and impeller rotation so the cooling circuit functions correctly under load.

• Flexible rubber impeller to move cooling water through the block
• Pump cup and wear plate to preserve tight clearances and reduce cavitation
• Pump housing and gasket to ensure a watertight assembly
• Bolts, washers, O-ring, pin, dowel and impeller key for secure installation

How easy is installation and what should I prepare?

Installation is straightforward for someone familiar with basic outboard maintenance. The kit’s components match OEM mounting points, so standard marine tools are typically sufficient. Still, prepare to drain coolant passages (flush with freshwater), use torque specs where required, and inspect the driveshaft and water passages for debris.

• Standard hand tools and marine grease recommended
• Follow Yamaha torque values and alignment pins when available
• Replace any worn hoses or thermostat components discovered during service
• Perform a post-installation waterflow test before returning to open water

What materials and design details improve durability?

The kit pairs a resilient rubber impeller with a precisely machined wear plate and housing to maintain close tolerances. These parts reduce slippage and minimize wear on the impeller blades, helping preserve pump efficiency under normal operating conditions.

• Rubber impeller formulated to resist heat and abrasion
• Metal wear plate and housing for dimensional stability and longevity
• Corrosion-resistant fasteners included for marine environments
• Complete seal kit to prevent leaks and preserve pump vacuum

Who is this for: Boat owners, marine technicians, and DIY mechanics running Yamaha 115–300 HP outboards who need a full pump rebuild kit that matches OEM form and function. Choose this GHmarine 61A-W0078 kit when you want all required parts in one purchase, compatibility with common Yamaha reference numbers, and components sized to restore reliable engine cooling without custom modifications.