Water Pump Impeller Kit – Fits Yamaha 15/20HP 4-Stroke (Replaces 6AH-W0078-00)

Water Pump Impeller Kit – Fits Yamaha 15/20HP 4-Stroke (Replaces 6AH-W0078-00)

This comprehensive water pump impeller repair kit is engineered for specific Yamaha 4-stroke outboard motors, providing a direct replacement solution for maintaining your engine's cooling system. It is designed to fit Yamaha F15C and F20 models manufactured from 2006 to the present.

This kit serves as a direct replacement for Yamaha part numbers 6AH-W0078-00-00, 6AH-W0078-01-00, and 6AH-W0078-02-00, as well as Sierra aftermarket part number 18-3479.

• Complete Kit: Includes all necessary components for a full water pump service, from the housing and impeller to gaskets and bolts.
• Durable Materials: Features a cast iron housing and a neoprene rubber impeller for reliable performance and longevity.
• Direct-Fit Installation: Engineered to meet OEM specifications for a precise fit and straightforward installation.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Yamaha owners, here’s a guide to help you identify your engine’s serial/model: Yamaha Serial Number Guide. You can also review exploded diagrams to verify part numbers: Yamaha Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x Water Pump Housing (6AH-44311-00-00)
• 1 x Cartridge Insert (63V-44322-00-00)
• 1 x Water Seal Damper (6L2-44367-00-00/6L2-44367-01-00)
• 1 x Impeller (63V-44352-01-00)
• 1 x Woodruff Key (664-44338-00-00)
• 1 x O-Ring (93210-49046-00)
• 1 x Cartridge Outer Plate (68T-44323-00-00)
• 2 x Dowel Pins (93604-10M03-00/93604-12M07-00)
• 4 x Bolts (97095-08045-00)
• 2 x Plates (63V-44328-01-00)

Installation Guide

1. Safety First: Before starting, disconnect the engine's battery and ensure the engine is securely mounted.
2. Access the Lower Unit: Shift the engine into neutral. Locate and remove the bolts securing the lower unit (gearcase) to the engine's midsection.
3. Detach the Lower Unit: Carefully separate the lower unit from the rest of the engine. Be mindful of the driveshaft and shift shaft.
4. Remove Old Pump: Unscrew the bolts on the water pump housing and slide the old housing assembly up and off the driveshaft.
5. Disassemble & Clean: Remove the old impeller, key, plates, and gaskets. Thoroughly clean all mounting surfaces, removing any old gasket material or corrosion.
6. Install New Components: Place the new plate and gasket onto the gearcase. Install the new Woodruff key into the driveshaft slot.
7. Install Impeller: Slide the new impeller onto the driveshaft. Important: Rotate the driveshaft clockwise while pushing the impeller down into the housing to correctly orient the vanes.
8. Complete Assembly: Install the remaining components from the kit, including the housing, seals, and bolts. Torque the bolts to the manufacturer's specification.
9. Reattach Lower Unit: Reinstall the lower unit, ensuring the driveshaft, shift shaft, and water tube align correctly. Fasten the bolts securely.
10. Final Checks: Reconnect the battery. Start the engine using a water supply (flushing muffs or in water) and confirm a steady stream of water from the tell-tale outlet.

Troubleshooting & FAQ

How can I be certain this kit will fit my Yamaha outboard?
This kit is specifically designed for Yamaha F15C and F20 4-stroke models from 2006 to the present. The most reliable method is to confirm your engine's model and year are listed in the compatibility table. You can also cross-reference the OEM part number 6AH-W0078-00-00 (or its successors) with your service manual.

What are the signs of a failing water pump?
The most common signs include your engine overheating, a weak or intermittent water stream from the "tell-tale" outlet, or a high-temperature alarm. A visual inspection of the old impeller might show cracked, brittle, or permanently bent vanes, which indicates a clear need for replacement.

How often should I replace my water pump impeller?
As a preventative maintenance measure, it is recommended to replace the impeller and seals every 1-2 years or every 100-200 hours of use, whichever comes first. This interval should be shortened if you frequently operate in saltwater or water with high levels of sand or silt.

OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?
We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?
This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.