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

Water Pump Impeller Kit – Fits Yamaha 25–70 HP Outboards (Replaces 663-44311-02)Water Pump Impeller Kit Fits Yamaha 2570 HP Outboards This water pump impeller kit is a comprehensive solution for rebuilding the water pump assembly on Yamaha outboard motors from 25 to 70 horsepower. It is engineered to restore the cooling system to its original performance, preventing engine overheating and ensuring long term reliability. This kit directly replaces Yamaha OEM part numbers: 663 W0078 01, 663 W0078 A0, 6H3 W0078 02 00, and 6H3 W0078

Water Pump Impeller Kit – Fits Yamaha 25–70 HP Outboards

This water pump impeller kit is a comprehensive solution for rebuilding the water pump assembly on Yamaha outboard motors from 25 to 70 horsepower. It is engineered to restore the cooling system to its original performance, preventing engine overheating and ensuring long-term reliability.

This kit directly replaces Yamaha OEM part numbers: 663-W0078-01, 663-W0078-A0, 6H3-W0078-02-00, and 6H3-W0078-A0-00.

• Fitment: Designed for Yamaha 2-Stroke outboards from 25 HP to 70 HP (1984–2005).
• Complete Assembly: Includes all necessary components shown in the detailed parts list for a full water pump service.
• Installation: Installs directly as a replacement for the original factory components without modification.

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 x Cartridge Insert (663-44322-00-00)
• 1 x Impeller (6H3-44352-00-00)
• 1 x Water Pump Gasket (663-44315-A0-00)
• 1 x Cartridge Outer Plate (663-44323-00-00)
• 1 x Cartridge Gasket (663-44324-A0-00)
• 2 x Bolts (97095-08055-00)
• 2 x Bolts (97095-08045-00)
• 1 x Water Seal Damper 2 (663-44366-00-00)
• 1 x Woodruff Key (90280-03M03-00)

Installation Guide

1. Disconnect the battery and remove the engine cover.
2. Drain the lower unit gear oil.
3. Remove the lower unit by unbolting it from the midsection.
4. Remove the old water pump housing bolts and lift the housing off.
5. Take note of the old components and remove the old impeller, gaskets, and plates.
6. Clean all mating surfaces thoroughly.
7. Install the new gaskets, plates, impeller, and key from the kit.
8. Lubricate the inside of the housing and the new impeller with a marine-safe lubricant.
9. Reinstall the water pump housing and torque the bolts to the manufacturer's specification.
10. Reattach the lower unit, refill the gear oil, and reconnect the battery.
11. Start the engine and verify water is discharging from the tell-tale port.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my specific engine?
A: The surest method is to check your original part number against the ones listed in this description. You can also consult our Compatible Engine Models table and use the Yamaha Serial Number Guide to verify your motor's model and year.

Q: What are the symptoms of a failing water pump impeller?
A: Common signs include the engine overheating at idle or low speeds, a weak or non-existent stream from the "tell-tale" water outlet, or a high engine temperature alarm.

Q: How often should I replace my water pump impeller?
A: As a general rule, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of use, depending on operating conditions (e.g., saltwater vs. freshwater).

Q: Is the complete water pump housing included?
A: This is an impeller repair kit and does not include the main pump housing. It is designed to rebuild your existing housing assembly with all new wear parts.

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.