Water Pump Impeller Kit – Fits Yamaha 50 60 70 HP Outboards (Replaces 6H3-W0078-02-00, 6H3-W0078-00)

Water Pump Impeller Kit – Fits Yamaha 50 60 70 HP Outboards (Replaces 6H3-W0078-02-00, 6H3-W0078-00)

This water pump impeller repair kit is designed for a wide range of Yamaha outboard motors. It provides a reliable solution for maintaining your engine's cooling system, ensuring optimal performance and preventing overheating. The kit is compatible with various 2-stroke (50–70 HP, 1984–2003) and 4-stroke (40–60 HP, 1999–2019) models.

This kit serves as a direct replacement for Yamaha OEM part numbers 6H3-W0078-00, 6H3-W0078-02, and 6H3-W0078-A0-00. It also cross-references with Sierra parts 18-3464, 18-3465, and 18-3466, as well as GLM parts 12057 and 12283.

• Includes a complete set of components for a full water pump service, including impeller, housing, gaskets, and bolts.
• The impeller is made from durable CR Neoprene Rubber for longevity and performance.
• Installation occurs in the lower unit gearcase.

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.

Yamaha 2-Stroke Models

Yamaha 4-Stroke Models

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (6H3-44352-00-00)
• 1 x Woodruff Key (90280-03M03-00)
• 1 x Cartridge Insert (663-44322-00-00)
• 1 x Cartridge Outer Plate (6H3-44323-00-00)
• 1 x Cartridge Gasket (6H3-44324-A0-00)
• 1 x Water Pump Gasket (6H3-44315-A0-00)
• 1 x Water Pump Gasket (688-44316-A0-00)
• 1 x O-Ring (93210-46044-00)
• 2 x Bolt With Washer (90119-08M14-00)
• 2 x Bolt With Washer (90119-08M33-00)

Installation Guide

1. Safety First: Disconnect the battery and remove the spark plug wires to prevent accidental starting.
2. Access the Lower Unit: Place the outboard motor in a secure position. Drain the gearcase oil.
3. Remove the Lower Unit: Unbolt the lower unit (gearcase) from the upper section of the motor. This usually involves removing several bolts, including one potentially hidden under the trim tab.
4. Access the Water Pump: With the lower unit removed, locate the water pump housing on top of the gearcase.
5. Disassemble the Housing: Unscrew the bolts holding the water pump housing in place and carefully lift it off, noting the position of all parts.
6. Remove Old Impeller: Slide the old impeller off the driveshaft. You may need to gently pry it. Remove the old Woodruff key from the shaft.
7. Clean and Inspect: Clean all surfaces of the housing, base plate, and gaskets. Inspect for wear, cracks, or warping.
8. Install New Components: Place the new gaskets and plates. Insert the new Woodruff key into the driveshaft and slide the new impeller on, rotating the shaft in its normal direction of operation to seat the vanes correctly.
9. Reassemble the Housing: Apply a light coat of marine grease to the inside of the new insert/cup and place it over the impeller. Secure the housing with the new bolts and O-ring.
10. Reattach Lower Unit: Guide the driveshaft back into the engine and reattach the lower unit. Torque bolts to the manufacturer's specification.
11. Refill and Test: Refill the gearcase with fresh oil. Reconnect the battery and spark plugs.
12. Final Check: Start the engine in water and immediately check the tell-tale for a strong, steady stream of water, indicating the pump is working correctly.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my engine?
A: The best way is to check your original part number against the ones listed in our "Part Number Cross-Reference" table. You can also use our "Compatible Engine Models" tables to find your specific model and year. When in doubt, consulting your engine's service manual or a qualified mechanic is recommended.

Q: What are the signs of a failing water pump impeller?
A: Common signs include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "tell-tale" outlet, or a high-temperature alarm sounding. Visible damage to the impeller vanes (cracks, missing pieces, stiffness) during inspection also indicates it's time for a replacement.

Q: How often should I replace the water pump impeller?
A: As a general rule of thumb, it is recommended to inspect and/or replace the water pump impeller every 1-2 years or every 100-200 hours of use, whichever comes first. This interval can change based on operating conditions, especially in saltwater or sandy/silty environments.

Q: OEM vs. Aftermarket?
A: 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.

Q: How fast do you ship and how much does it cost?
A: 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.

Q: What is your warranty and return policy?
A: 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.