Water Pump Impeller Repair Kit – Fits Yamaha F50A 4-Stroke (1991-2007)

Water Pump Impeller Repair Kit for Yamaha 4-Stroke & 2-Stroke Outboards

This water pump impeller repair kit provides the necessary components to service and restore the cooling system on select Yamaha 4-stroke and 2-stroke outboard engines. It is designed to meet or exceed original equipment specifications for reliable performance.

This kit directly replaces Yamaha OEM part numbers 6BG-W0078-00-00 and 6BG-W0078-01-00, along with other aftermarket equivalents.

• Installation Type: Direct OEM-fit replacement.
• Key Component Included: Comes with the essential Impeller (6H4-44352-02-00) required for the repair.
• Primary Function: Restores cooling system efficiency to prevent engine overheating.

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

Installation Guide

1. Disconnect the negative battery cable for safety.
2. Remove the lower unit (gearcase) from the outboard by unbolting it from the engine leg.
3. Locate and remove the bolts securing the water pump housing.
4. Carefully lift the housing off, noting the rotational direction of the existing impeller vanes.
5. Remove the old impeller, Woodruff key, gaskets, and wear plates.
6. Clean all mating surfaces of any old gasket material or corrosion.
7. Install the new components from the kit, starting with the Woodruff key and cartridge insert/plate.
8. Lightly lubricate the new impeller and the inside of the housing with marine grease.
9. Install the new impeller by pushing down and rotating the driveshaft clockwise to bed the vanes correctly.
10. Reinstall the water pump housing and tighten the bolts to the manufacturer's specified torque.
11. Reattach the lower unit to the engine and reconnect the battery.
12. Test the engine on a water supply (flusher or in water) to confirm a strong tell-tale stream.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?
Refer to the "Compatible Engine Models" table to verify your exact model and horsepower. This kit is designed for Yamaha 4-stroke models F25B, F30A, F40B, F50A (1991-2007) and 2-stroke E40X/40X models, replacing OEM part 6BG-W0078-01-00.

What are the signs that my water pump impeller is failing?
Common symptoms include the engine overheating at idle or low speeds, a weak or intermittent water stream from the "telltale" outlet, or finding cracked, brittle, or permanently bent vanes on the impeller during inspection.

How often should I replace the water pump impeller?
As a crucial part of preventative maintenance, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of operation. Replacement frequency should be increased in saltwater or high-debris environments.

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.