Water Pump Impeller Kit – Fits Yamaha 25-70 HP (Replaces 663-44311-02)

Water Pump Impeller Kit – Fits Yamaha 25-70 HP (Replaces 663-44311-02)

This water pump impeller service kit is designed for a wide range of Yamaha 2-stroke and 4-stroke outboard engines, from 25 HP to 70 HP. It provides the necessary components for repairing or rebuilding the engine's water pump, a critical part of the cooling system.

This assembly is a direct replacement for multiple Yamaha and aftermarket part numbers, ensuring broad compatibility with various models produced between 1984 and 2000.

• Installation Method: Drop-in replacement for the original water pump assembly.
• Quality Manufacturing: Produced in an ISO9002 certified facility to meet or exceed OEM specifications.
• Complete Kit: Includes a new impeller, housing insert, gaskets, plate, and bolts required for a full service.

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 Engines

Yamaha 4-Stroke Engines

Technical Specifications

Package Contents

• 1 x Water Pump Gasket (663-44315-A0-00)
• 1 x Cartridge Insert (663-44322-00-00)
• 1 x Cartridge Outer Plate (663-44323-00-00)
• 1 x Cartridge Gasket (663-44324-A0-00)
• 1 x Water Seal Damper 2 (663-44366-00-00)
• 1 x Impeller (6H3-44352-00-00)
• 1 x Woodruff Key (90280-03024-00)
• 2 x Bolts (97095-08045-00)
• 2 x Bolts (97095-08055-00)

Installation Guide

1. Safety First: Disconnect the engine's battery and ensure the engine is off and cool.
2. Access the Pump: Remove the lower unit (gearcase) from the outboard motor by unbolting it.
3. Disassemble Housing: Carefully unbolt and remove the water pump housing to expose the old impeller.
4. Note Old Impeller: Pay close attention to the orientation of the impeller vanes before removing it.
5. Clean & Inspect: Thoroughly clean the inside of the pump housing and inspect it for any cracks, scoring, or warping.
6. Install New Components: Install the new gaskets, plate, and impeller from the kit. Ensure the impeller vanes are oriented correctly (typically clockwise).
7. Reassemble Pump: Securely fasten the water pump housing, tightening the bolts to the manufacturer's specified torque.
8. Reinstall Lower Unit: Re-attach the lower unit to the outboard motor.
9. Test Operation: Connect a water supply ("earmuffs" or by submerging the unit) and run the engine at idle to confirm a steady stream of water from the tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my specific Yamaha engine?

A: First, check your engine's model and year against the "Compatible Engine Models" table above. This kit replaces several OEM part numbers, including 663-44311-02 and 6H4-W0078-A0-00. For further verification, we recommend using the Yamaha Serial Number Guide and reviewing the diagrams in the Yamaha Parts Catalog to match the parts exactly.

Q: What are the common signs of a failing water pump impeller?

A: The most common indicators include the engine overheating, a weak or non-existent water stream from the "tell-tale" cooling outlet, or discovering the old impeller is dry, brittle, cracked, or has missing vanes during an inspection.

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

A: As a general rule, it is recommended to inspect the impeller annually and replace it every 1-2 years or after 100-200 hours of operation. Frequent use in saltwater or sandy/silty water may require more frequent replacement.

Q: 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.

Q: 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.

Q: 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.