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

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

This water pump impeller service kit provides everything needed for a complete replacement on select Yamaha 15 HP and 20 HP 4-stroke outboard motors. It is designed to restore the performance and reliability of your engine's cooling system.

This kit is a direct replacement for Yamaha part numbers 6AH-W0078-00-00, 6AH-W0078-01-00, 6AH-W0078-02-00, and aftermarket kit Sierra 18-3479. It is also an equivalent kit for Yamaha 68T-W0078-00-00.

• Engineered to meet original OEM specifications for a precise fit and reliable function.
• Includes all necessary gaskets, plates, and hardware for a complete service.
• Restores cooling system efficiency to prevent engine overheating.

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 Water Pump 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 (6AH-44323-00-00/68T-44323-00-00)
• 2 x Plate (63V-44328-01-00)
• 2 x Dowel Pin (93604-10M03-00/93604-12M07-00)
• 4 x Bolt (97095-08045-00)

Installation Guide

1. Disconnect the negative battery terminal for safety.
2. Remove the lower unit from the outboard motor.
3. Unbolt and remove the old water pump housing.
4. Carefully take out the old impeller, key, and gaskets. Note their orientation.
5. Clean all mating surfaces thoroughly, removing any old gasket material.
6. Install the new key, impeller, gaskets, and seals from the kit.
7. Place the new housing and cartridge components, ensuring a proper seal.
8. Torque the housing bolts to the manufacturer's recommended specification.
9. Reinstall the lower unit, ensuring the driveshaft and water tube align correctly.
10. Reconnect the battery and test the engine in water, checking for proper water flow from the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?
First, check our Part Number Cross-Reference table to see if your old part number is listed. Next, review the Compatible Engine Models table to ensure your specific Yamaha model and year range are included. Using our linked Yamaha Serial Number Guide can help you verify your engine details.

What are the signs of a failing water pump impeller?
Common signs include the engine overheating, a weak or non-existent water stream from the "tell-tale" outlet, or an audible alarm from the engine's warning system. Cracks, stiffness, or missing fins on the old impeller are also clear indicators that a replacement is needed.

How often should I replace the water pump impeller?
For preventative maintenance, we recommend replacing the impeller every 1-2 years or every 100-200 hours of use, depending on operating conditions. Frequent use in saltwater or sandy/murky water may require more frequent inspections and replacements.

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.