679-W0078-A0 Water Pump Impeller Kit for Yamaha OMC C40 235 240 | JLM Marine

Water Pump Impeller Kit – Fits Yamaha 2-Stroke 40 HP C40 & OMC Cobra Stern Drive 235/240

This water pump impeller kit is engineered for Yamaha 2-Stroke 40 HP C40 outboards (1990–1997) and OMC Cobra Stern Drive models 235 (1971, 1975–1977) and 240 (1978). It provides a direct replacement solution for critical cooling system components, ensuring reliable water flow and consistent engine temperature regulation.

This kit directly replaces Yamaha part numbers 6F5-44352-00, 6F5-44352-A0, 679-W0078-00, 679-W0078-A0 and Sierra Marine 18-3374, 18-3397, 18-3398. All components are designed to meet OEM specifications for precise fitment and performance.

• Complete kit includes impeller, key, gaskets, and seal for a comprehensive rebuild
• Compatible with both Yamaha outboard and OMC stern drive applications
• Designed for saltwater and freshwater cooling systems

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

This complete water pump impeller kit includes the following components:

• 1 × Water Pump Impeller (6F5-44352-00, 676-44352-00)
• 1 × Key, Impeller (90280-04M00-00)
• 1 × Gasket, Water Pump (676-44315-A0-00)
• 1 × Gasket, Water Pump (676-44324-A0-00)
• 1 × Gasket, Water Pump (679-44316-A0-00)
• 1 × Seal, Water (663-44366-00-00)

Installation Guide

1. Disconnect the fuel line and remove the lower unit from the outboard or stern drive following manufacturer service manual procedures.
2. Remove the water pump housing cover and old impeller. Inspect the housing for wear, scoring, or corrosion.
3. Clean all gasket surfaces thoroughly using a gasket scraper and solvent to ensure a proper seal.
4. Install the new impeller key into the driveshaft slot, ensuring it is seated firmly.
5. Lubricate the new impeller with marine-grade grease or glycerin. Insert it onto the driveshaft, aligning the key slot.
6. Rotate the impeller blades in the direction of normal rotation to ensure they are correctly oriented.
7. Install the new gaskets in the correct order as specified in your service manual, applying a thin layer of marine sealant if recommended.
8. Reinstall the water pump housing, ensuring all fasteners are tightened to the manufacturer's specified torque values.
9. Reattach the lower unit to the outboard or stern drive, reconnect the fuel line, and check for proper alignment.
10. Submerge the lower unit in water or connect a flushing device. Start the engine and verify strong water flow from the cooling system tell-tale.
11. Allow the engine to reach operating temperature and inspect all seals and gaskets for leaks.
12. If leaks or weak water flow are detected, shut down immediately and re-inspect the installation.

Troubleshooting & FAQ

Q: How do I confirm this impeller kit fits my engine?
A: Verify your engine model and year against the compatibility table above. Cross-reference your existing part numbers (found on the old impeller or in your service manual) with the part number cross-reference table to confirm fitment.

Q: How often should I replace the water pump impeller?
A: Most manufacturers recommend replacing the impeller every 2–3 years or 200–300 hours of operation, whichever comes first. If you operate in sandy or debris-filled water, inspect and replace more frequently.

Q: What are the signs of a failing water pump impeller?
A: Common symptoms include weak or no water flow from the tell-tale, engine overheating, reduced power, steam from the engine, or visible impeller damage such as cracked, broken, or glazed blades.

Q: Can I reuse the old gaskets and seals?
A: No. Always replace all gaskets and seals during a water pump rebuild to prevent leaks and ensure proper cooling system pressure and performance.

Q: What is the difference between OEM and aftermarket impeller kits?
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.