Water Pump Impeller Kit – Fits Yamaha 20D/25D/25N 2-Stroke Outboards (Replaces 6L2-W0078-00-00)

Water Pump Impeller Kit – Fits Yamaha 20D/25D/25N 2-Stroke Outboards

This water pump impeller service kit is designed for Yamaha 2-stroke 20 HP and 25 HP outboards (1988–2004), including 20D, 25D, and 25N models. It provides all necessary components for a complete water pump rebuild, minus the housing, ensuring your engine’s cooling system functions reliably.

This kit is a direct replacement for Yamaha part number 6L2-W0078-00-00, Sierra 18-3431, and Mercury 879137.

• Engine Compatibility: Fits specific Yamaha 2-stroke 20HP & 25HP models.
• Installation Type: Drop-in replacement for the original water pump components.
• Complete Kit: Includes impeller, o-ring, outer plate, insert, key, bolts, and washers.

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 Outer Plate (6L2-44323-00-00)
• 1 x O-Ring (93210-45161-00)
• 1 x Impeller (6L2-44352-00-00)
• 1 x Cartridge Insert (6L2-44322-00-00)
• 4 x Bolts (97095-06040-00)
• 1 x Woodruff Key (90280-03024-00)
• 4 x Washers (92990-06600-00)
• Note: This service kit does not include the pump housing.

Installation Guide

1. Safety First: Disconnect the battery and ensure the engine is in a secure, stable position.
2. Access the Lower Unit: Remove the bolts connecting the lower unit (gearcase) to the upper engine casing and carefully lower it.
3. Locate Pump Housing: The water pump is typically located on top of the gearcase, around the driveshaft.
4. Remove Old Components: Unscrew the bolts securing the pump housing. Remove the housing, old impeller, wear plate, and gaskets.
5. Clean and Inspect: Thoroughly clean the housing interior and all surfaces. Inspect the housing for cracks, warping, or scoring.
6. Install New Parts: Install the new cartridge insert and outer plate. Slide the new Woodruff key onto the driveshaft and install the new impeller, rotating it in the correct direction.
7. Reassemble Pump: Apply a light marine-grade lubricant to the inside of the housing and reinstall it over the new impeller with the new O-ring.
8. Secure Housing: Fasten the housing with the new bolts and washers, tightening them to the manufacturer's specified torque.
9. Reattach Lower Unit: Carefully guide the lower unit back into place, aligning the driveshaft, and secure it with its mounting bolts.
10. Test Operation: Reconnect the battery and run the engine with a proper water supply (using "ear muffs" or in the water). Check for a steady stream of water from the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?
Your primary check should be against the compatible engine models table. Verify your Yamaha model (e.g., 20D, 25N) and year falls within the specified range. Cross-referencing your existing part number with 6L2-W0078-00-00 is the best way to ensure an exact match.

What are the signs of a failing water pump impeller?
Common symptoms include a weak or non-existent water stream from the "tell-tale" outlet, engine overheating alarms, or a melted/distorted pump housing from excessive friction and heat.

How often should I replace the water pump impeller?
For preventative maintenance, it is recommended to inspect the impeller annually and replace it 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.

Does this kit include the water pump housing?
No, this is a repair and service kit that includes the impeller and all related gaskets, plates, and hardware. It is designed to be installed into your existing pump housing. If your housing is cracked, warped, or heavily scored, it must be purchased separately.

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.