Water Pump Impeller – Fits Yamaha 25–50 HP 2-Stroke Outboards
Water Pump Impeller – Fits Yamaha 25–50 HP 2-Stroke Outboards is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller – Fits Yamaha 25–50 HP 2-Stroke Outboards
Water Pump Impeller – Fits Yamaha 25–50 HP 2-Stroke Outboards is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump impeller is a direct-fit replacement for selected Yamaha 25–50 HP 2-stroke outboard water pump applications. The flexible marine-grade rubber impeller is designed to restore water-pump circulation and help maintain proper engine cooling.
This impeller corresponds to Yamaha water pump impeller reference 6H4-44352-02 and is associated with water pump service reference 6H4-W0078-00. Always compare the original impeller, keyway, engine model, year, and serial-number range before ordering.
- Aftermarket replacement for the water pump impeller.
- Durable marine-grade rubber construction for regular marine service.
- Designed for straightforward replacement when the existing pump housing and related components are serviceable.
- Suitable for preventative maintenance or replacement of a worn impeller.
Part Number References
Use the following references to help compare the replacement with your existing part and service information.
| Brand or Reference | Part Number | Reference Type |
|---|---|---|
| Yamaha | 6H4-44352-02 | Water pump impeller reference |
| Yamaha | 6H4-W0078-00 | Water pump service reference |
| Sierra | 18-3415, 18-3434 | Related catalog references; verify component scope before purchase |
| GLM | 12276 | Related aftermarket reference; verify component scope before purchase |
Engine Compatibility
This impeller is intended for selected Yamaha 25–50 HP 2-stroke outboards using the 6H4 impeller pattern. Model, year, shaft configuration, and serial-number conditions can affect fitment, so confirm the complete engine identification before ordering.
| Brand | Rated Horsepower | Stroke | Impeller Reference | Fitment Note |
|---|---|---|---|---|
| Yamaha | 25–50 HP | 2-Stroke | 6H4-44352-02 | Selected applications; confirm exact model, year, and serial number |
Do not use the broad horsepower range alone as confirmation of fitment. Compare your original part and consult the applicable Yamaha parts diagram or service information for the exact engine.
Technical Specifications
- Product Type
- Water pump impeller
- Application
- Selected Yamaha 25–50 HP 2-stroke outboards
- Construction
- Marine-grade rubber impeller
- Impeller Dimensions
- 51.2 mm outer diameter × 16.1 mm inner diameter × 19.05 mm height
- Replacement Scope
- Impeller only; not a complete water pump repair kit
- Product Status
- Aftermarket replacement, not an OEM-manufactured component
What's in the Box
- 1 x Water pump impeller
Not included: water pump housing, wear plate, gaskets, O-rings, Woodruff key, bolts, or other water pump repair-kit components unless specifically shown and stated in the order details.
Installation Notes
- Disconnect the battery and follow the outboard manufacturer's safety procedures.
- Remove the lower unit according to the service instructions for your exact engine.
- Remove the water pump cover or housing to access the old impeller.
- Remove the old impeller and inspect the drive key, keyway, housing, wear plate, gaskets, and seals.
- Clean the pump area and replace any damaged or worn related components before reassembly.
- Install the drive key and new impeller on the driveshaft. Turn the impeller in the correct direction as the housing is installed so the vanes seat properly.
- Reinstall the housing, cover, and sealing components using the manufacturer's torque specifications.
- Reattach the lower unit and confirm that all fasteners and connections are secure.
- Run the engine only in an appropriate water supply and verify a steady cooling-water tell-tale stream before normal operation.
Troubleshooting & FAQ
How do I confirm that this impeller fits my Yamaha outboard?
Check the complete engine model, horsepower, stroke, year, and serial-number range against the applicable parts information. Also compare the original impeller's outside diameter, inside diameter, height, keyway, and vane configuration with the specifications shown on this page.
What are common signs of a worn water pump impeller?
Symptoms may include engine overheating, especially at idle or low speed, a weak or missing tell-tale stream, damaged or permanently curved vanes, or visible cracking and brittleness.
Does this listing include a complete water pump repair kit?
No. This listing is for one flexible rubber water pump impeller only. The housing, wear plate, gaskets, O-rings, key, bolts, and other repair components are not included.
Is this an OEM Yamaha part?
No. This is an aftermarket replacement manufactured to match the applicable impeller dimensions and reference application. Yamaha and other brand names and part numbers are used only to identify compatibility and reference information.
How often should a water pump impeller be replaced?
Inspect the impeller during scheduled water pump service and replace it when the vanes are cracked, brittle, worn, or permanently deformed. Service more frequently when the outboard operates in saltwater, silty water, or other abrasive conditions.
Can I install the impeller without replacing the housing?
Yes, if the housing, wear plate, key, gaskets, and seals are within serviceable condition. Replace any component that is scored, warped, damaged, or excessively worn to avoid premature impeller failure.
Safety & Important Information
- Confirm fitment using the complete engine model and serial-number information before purchase.
- Compare the product dimensions and appearance with the original part before installation.
- Do not operate an outboard without an adequate water supply for cooling.
- Professional installation is recommended when lower-unit removal or water-pump service is unfamiliar.
- This is an aftermarket replacement and is not manufactured by Yamaha.
About Sea Sierra
- Marine Replacement Parts — Practical aftermarket components for routine repair and maintenance.
- Fitment-Focused Information — Clear reference numbers and application details to support accurate part comparison.
- Manufacturer-Direct Value — Competitive replacement parts selected for everyday marine service.
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