Water Pump Impeller Kit – Fits Yamaha 2-Stroke 40HP (Replaces 6F5-W0078-A0-00, 679-W0078-A1-00)

Water Pump Impeller Kit – Fits Yamaha 2-Stroke 40HP (Replaces 6F5-W0078-A0-00, 679-W0078-A1-00)

This aftermarket water pump repair kit is designed for Yamaha 2-stroke 40HP outboard engines manufactured between 1990 and 1997, providing a reliable solution for maintaining your engine's cooling system. It is engineered to fit C40 and CV40 series models, ensuring comprehensive coverage for the specified years.

The kit serves as a direct replacement for Yamaha OEM part numbers 6F5-W0078-A0-00 and 679-W0078-A1-00, as well as Sierra aftermarket parts 18-3374, 18-3397, and 18-3398.

• Engineered as a direct OEM replacement for straightforward installation.
• Compatible with a wide range of Yamaha 40HP 2-Stroke outboard models from 1990-1997.
• Includes a new impeller, housing, wear plate, gaskets, seals, and all necessary hardware for a complete overhaul.

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 × Impeller (6F5-44352-00-00)
• 1 × Wear Plate / Cartridge Outer Plate (676-44323-00-00)
• 1 × Insert Cup (676-44322-00-00)
• 1 × Water Pump Gasket / Cartridge Gasket (676-44324-A0-00 / 676-44324-A1-00)
• 1 × Water Pump Outer Gasket (676-44315-A0-00 / 676-44315-A1-00)
• 1 × Water Pump Gasket (679-44316-A0-00)
• 1 × Water Seal Damper 2 (663-44366-00-00 / 663-44366-01-00)
• 1 × Woodruff Key / Impeller Key (90280-04M00-00)
• 2 × Bolts (97095-08055-00)
• 2 × Bolts (97095-08045-00)
• 4 × Washers (92990-08600-00)

Installation Guide

1. Disconnect the battery and drain the gearcase oil before starting.
2. Unbolt and carefully remove the lower gearcase unit from the outboard engine leg.
3. Remove the bolts on the water pump housing and lift it off to expose the impeller and wear plate.
4. Take out the old impeller, gaskets, seals, and wear plate, noting their order and orientation.
5. Thoroughly clean all mating surfaces, removing any old sealant or corrosion.
6. Install the new wear plate, gaskets, and woodruff key. Slide the new impeller onto the driveshaft, rotating it clockwise to bend the vanes correctly.
7. Place the new housing over the impeller and tighten the bolts to the specified torque.
8. Carefully reinstall the lower unit, ensuring the driveshaft, water tube, and shift shaft are aligned.
9. Refill the gearcase with fresh oil. Reconnect the battery and test the engine with a water supply, checking for strong water flow from the tell-tale.

Troubleshooting & FAQ

How do I confirm this kit fits my specific engine?
This kit fits Yamaha 40HP 2-stroke models CV40 and C40 from 1990–1997. Please check the "Compatible Engine Models" table on this page and match your exact model number (e.g., C40ELR) and year. Cross-referencing your old part number with the ones listed (6F5-W0078-A0-00, 679-W0078-A1-00) is the best way to guarantee a match.

What are the signs of a failing water pump impeller?
Common signs include a weak or non-existent water stream from the tell-tale outlet, an engine overheat alarm, or visible cracks and missing vanes on the old impeller during inspection. You may also notice the engine running hotter than usual.

How often should a water pump impeller be replaced?
As a general maintenance guideline, impellers should be inspected annually and replaced every 1-2 years, depending on usage (hours) and operating conditions (saltwater vs. freshwater). Frequent use in sandy or silty water may require more frequent replacement.

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.