Water Pump Impeller Repair Kit – Fits Yamaha 2HP 2-Stroke Outboards (Replaces 6A1-W0078-02-00)
Water Pump Impeller Repair Kit – Fits Yamaha 2HP 2-Stroke Outboards (Replaces 6A1-W0078-02-00) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
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Water Pump Impeller Repair Kit – Fits Yamaha 2HP 2-Stroke Outboards...
Water Pump Impeller Repair Kit – Fits Yamaha 2HP 2-Stroke Outboards (Replaces 6A1-W0078-02-00) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Repair Kit – Fits Yamaha 2HP 2-Stroke Outboards (Replaces 6A1-W0078-02-00) is designed to restore the cooling system on Yamaha 2HP 2-Stroke outboard motors from years 1984 through 2002. It provides all necessary components for a complete overhaul of the water pump assembly, ensuring reliable engine cooling and performance.
This kit is a direct alternative for Yamaha OEM parts 6A1-W0078-02-00, 6A1-W0078-01-00, 6A1-W0078-00-00, 6GD-W0078-00-00, and Sierra aftermarket numbers 18-3462 and 18-3463.
- Engineered for direct OEM replacement fit and function.
- Restores critical cooling system performance.
- Includes a complete set of seals, gaskets, impeller, and hardware.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 6A1-W0078-02-00 |
| Yamaha | 6A1-W0078-01-00 |
| Yamaha | 6A1-W0078-00-00 |
| Yamaha | 6GD-W0078-00-00 |
| Sierra | 18-3462 |
| Sierra | 18-3463 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yamaha models, check your engine's model code and year to ensure a precise match. This kit fits a wide range of 2HP models from 1984–2002.
For Mariner models, this kit is compatible with select 2-stroke 2HP outboards. It is critical to verify fitment using your engine's serial number before ordering.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 2SF | 2 | 2-Stroke | 1989 | 6A1-W0078-02-00 | |
| Yamaha | 2SD | 2 | 2-Stroke | 1990 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHP | 2 | 2-Stroke | 1991 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHQ | 2 | 2-Stroke | 1992 | 6A1-W0078-02-00 | |
| Yamaha | 2MHR | 2 | 2-Stroke | 1993 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHR | 2 | 2-Stroke | 1993 | 6A1-W0078-02-00 | |
| Yamaha | 2MHS | 2 | 2-Stroke | 1994 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHS | 2 | 2-Stroke | 1994 | 6A1-W0078-02-00 | |
| Yamaha | 2MHT | 2 | 2-Stroke | 1995 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHT | 2 | 2-Stroke | 1995 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHU | 2 | 2-Stroke | 1996 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHV | 2 | 2-Stroke | 1997 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHW | 2 | 2-Stroke | 1998 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHX | 2 | 2-Stroke | 1999 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHY | 2 | 2-Stroke | 2000 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHKZ | 2 | 2-Stroke | 2001 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHZ | 2 | 2-Stroke | 2001 | 6A1-W0078-02-00 | |
| Yamaha | 2MSHA | 2 | 2-Stroke | 2002 | 6A1-W0078-02-00 | |
| Yamaha | Various 2HP | 2 | 2-Stroke | 1984–1987 | 6A1-W0078-02-00 | Early models |
| Mariner | 2HP Models | 2 | 2-Stroke | 6A1-W0078-02-00 | Compatible with select models (verify via serial number) |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit
- Installation
- Direct OEM replacement
- Other Technical Attributes
- For Yamaha 2HP cooling system
What’s in the Box
- 1 x Impeller (646-44352-01-00)
- 1 x Wear Plate (646-44323-00-00)
- 1 x Insert Cartridge Cup (646-44322-00-00)
- 1 x Cartridge Outer Plate (646-44323-00)
- 1 x Protector Oil Seal (6A1-44325-00-00)
- 1 x Oil Seal (93101-11M44-00)
- 1 x Damper, Water Seal (646-44366-01-00)
- 1 x "O" Ring (93210-19213-00)
- 2 x Dowel Pin (93604-09068-00)
- 2 x Bolt and Washer (97095-05016-00)
Installation Notes
- Disconnect the battery and ensure the engine is turned off and secured.
- Place a drain pan under the lower unit and remove the gearcase drain and vent plugs to empty the gear oil.
- Unbolt and carefully remove the lower unit from the outboard's driveshaft housing.
- Remove the old water pump housing, impeller, and associated seals and gaskets. Clean all mating surfaces thoroughly.
- Install the new components from the kit in reverse order of removal, ensuring all seals are properly seated and bolts are torqued to the manufacturer's specification.
- Reinstall the lower unit, refill the gearcase with fresh oil, and test the engine in the water to confirm proper cooling function (a steady stream of water from the tell-tale).
Troubleshooting & FAQ
How can I tell if my water pump is failing?
Common signs of a failing water pump include a weak or non-existent water stream from the "tell-tale" outlet, engine overheating alarms, or a noticeable decrease in engine performance. A worn impeller is the most frequent cause.
How often should the water pump impeller be replaced?
As a preventative maintenance measure, 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. Operation in sandy or silty water may require more frequent replacement.
Will this kit fit my specific engine if it's not on the list?
This kit is specifically designed for the models listed. Do not purchase if your model is not explicitly mentioned. You can cross-reference the OEM part numbers provided with your service manual or a local dealer to confirm compatibility.
Is the impeller material different from the original?
The impeller is made from a durable, high-quality neoprene compound designed to meet or exceed OEM specifications for longevity and performance in a marine environment.
Can I install this kit myself?
While installation can be performed by a mechanically inclined individual with the correct tools, we recommend professional installation to ensure all components are fitted correctly and the cooling system functions safely and effectively.
What is the difference between an OEM part and an aftermarket part?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. All our parts are manufactured in an ISO 9002 facility and are batch-inspected for consistency and quality.
What are your shipping speed and cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free, and expedited options will appear at checkout if they are available for your location.
What is your warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal use. If any issues arise, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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