Water Pump Impeller Kit – Fits Yamaha 50-70 HP Outboards (Replaces 6H3-W0078-02-00, 6H3-W0078-A0-00)

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

This water pump impeller service kit is designed for a wide range of Yamaha outboard motors, including 2-Stroke 60–70 HP (1992–2003) and 4-Stroke T50/FT50/T60/FT60 (1997–UP) models. It provides all the necessary components for a complete overhaul of your outboard's water pump assembly.

This kit is a direct replacement for Yamaha OEM part numbers 6H3-W0078-00-00, 6H3-W0078-A0-00, 6H3-W0078-02-00, and 6H3-44311-00-00. It also cross-references with Sierra part numbers 18-3461 and 18-3466.

• Complete Kit: Includes the impeller, wear plate, insert cup, gaskets, and water pump housing for a full service.
• Durable Materials: Features a neoprene impeller for flexibility and a nylon PA66 housing for corrosion resistance.
• Direct Installation: Engineered to meet OEM specifications for a direct fit and reliable performance.

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

Yamaha 4-Stroke

Technical Specifications

Package Contents

• 1 x Water Pump Gasket (688-44316-01-00/688-44316-A0-00)
• 1 x Water Pump Gasket (6H2-44315-00-00/6H2-44315-A0-00)
• 1 x Outer Plate Gasket (6H2-44324-00-00/6H2-44324-A0-00)
• 1 x Wear Plate (6H3-44323-00-00)
• 1 x Impeller (6H2-44352-00-00)
• 1 x Impeller Key (90280-03M03-00/90280-03M07-00)
• 1 x Insert Cup (663-44322-00-00)
• 1 x O-Ring (93210-46044-00)
• 1 x Water Pump Housing (6H2-44311-00-00)
• 2 x Bolt with washer (90119-08M14-00)
• 2 x Bolt with washer (90119-08M33-00)

Installation Guide

Follow these general steps to replace your water pump impeller kit. For detailed instructions specific to your model, consult your owner's manual or a professional mechanic.

1. Safety First: Disconnect the battery and disable the ignition system.
2. Access the Lower Unit: Shift the outboard into neutral. Remove the bolts securing the lower unit (gearcase) to the upper leg and carefully lower it.
3. Remove the Old Pump: Locate the water pump housing on top of the gearcase. Unbolt and remove the housing to access the impeller and other components.
4. Inspect and Clean: Clean the housing interior and mating surfaces. Inspect for scoring, warping, or corrosion.
5. Install New Components: Lightly grease the new wear plate and insert cup. Install the new impeller, making sure to turn the driveshaft clockwise to bend the vanes in the correct direction.
6. Reassemble the Pump: Install the new gaskets and O-ring. Secure the new water pump housing with the provided bolts, tightening them to the manufacturer's specified torque.
7. Reinstall Lower Unit: Guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align correctly. Secure it with the mounting bolts.
8. Test Operation: Reconnect the battery. Start the engine in a test tank or with a water flusher to confirm the pump is operating and water is exiting the tell-tale port.

Troubleshooting & FAQ

Q: How can I be sure this kit will fit my Yamaha engine?

A: The best way to ensure compatibility is to verify your engine's model and year against the lists in the "Compatible Engine Models" section. You can also match the OEM part numbers listed on your existing components to those in our "Part Number Cross-Reference" table.

Q: What are the signs that my water pump impeller needs to be replaced?

A: Common signs of a failing impeller include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "tell-tale" outlet port, and a dry, cracked, or brittle appearance of the old impeller upon inspection.

Q: How often should I replace my water pump impeller?

A: As a general maintenance guideline, it's recommended to inspect and/or replace your water pump impeller every 100-200 operating hours or at least once every 1-2 years, even if the engine isn't used frequently. This helps prevent unexpected failures on the water.

Q: What makes this kit different from others on the market?

A: This is a complete service kit that, unlike many basic kits, includes the water pump housing. This allows for a full replacement of all critical wear components, which is crucial if your existing housing is warped, cracked, or corroded.

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.