Water Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Replaces 66T-W0078-00)

Water Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Replaces 66T-W0078-00)

This water pump impeller kit is engineered for specific Yamaha outboard motors, including the T25, F30, and F40 horsepower models manufactured between 2000 and 2009. It provides a reliable solution for maintaining your engine’s cooling system.

This assembly serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring compatibility and restoring original performance.

• Installation Method: Direct replacement for a straightforward installation.
• Core Components: The kit is built around a durable 6-blade impeller designed for optimal water flow.
• Complete Assembly: Includes all necessary gaskets, seals, plates, and hardware 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.

Technical Specifications

Package Contents

• 1 x Cartridge Insert (63D-44322-00-00)
• 1 x Cartridge Outer Plate (66T-44323-00-00)
• 1 x O-Ring (93210-59MG7-00)
• 1 x Water Pump Gasket (63D-44316-00-00)
• 1 x Woodruff Key (90280-03M03-00)
• 1 x Impeller (6H4-44352-02-00)
• 4 x Bolts, With Washer (90119-08M15-00)
• 1 x Water Seal Damper 2 (663-44366-00-00)
• 1 x Pump Housing Cover (63D-44312-00-00)

Installation Guide

1. Disconnect the negative battery cable.
2. Unbolt and carefully lower the gearcase/lower unit from the outboard's midsection.
3. Remove the water pump housing bolts and lift the housing to expose the impeller.
4. Note the rotational direction of the old impeller blades before removing it.
5. Remove the impeller, Woodruff key, wear plate, and gaskets.
6. Thoroughly clean all mating surfaces, removing any old gasket material or debris.
7. Install the new lower gasket, wear plate, and Woodruff key.
8. Slide the new impeller onto the drive shaft, rotating it clockwise to correctly orient the blades.
9. Install the new seals into the pump housing and place the housing over the impeller.
10. Apply a light coat of marine grease to the new bolts and tighten them to the manufacturer's specified torque.
11. Reattach the lower unit to the outboard motor.
12. Reconnect the battery and test the engine using a water supply to ensure proper cooling system function.

Troubleshooting & FAQ

How do I confirm this fits my engine?
Verify your engine's model and year against the "Compatible Engine Models" table. This kit is designed for Yamaha T25, F30, F40, 40XMH, and 40XE models within the specified years. Cross-referencing your existing part number with 66T-W0078-00 is the most reliable way to ensure a match.

What are the signs of a failing water pump impeller?
Key indicators include the engine overheating at low speeds, a weak or intermittent water stream from the tell-tale outlet, or a burnt rubber smell. Upon inspection, a worn impeller will appear cracked, brittle, or have fins that are permanently bent or broken.

How often should I replace the impeller?
As a critical part of preventative maintenance, we recommend replacing the water pump impeller every one to two years or after every 100-200 hours of operation. Frequency should be increased if you primarily operate in saltwater or sandy/silty conditions.

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.