Water Pump Impeller Kit – Fits Yamaha 25–70 HP Outboards (Replaces 663-44311-02)
Water Pump Impeller Kit – Fits Yamaha 25–70 HP Outboards (Replaces 663-44311-02) is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Water Pump Impeller Kit – Fits Yamaha 25–70 HP Outboards (Replaces ...
Water Pump Impeller Kit – Fits Yamaha 25–70 HP Outboards (Replaces 663-44311-02) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit – Fits Yamaha 25–70 HP Outboards (Replaces 663-44311-02) is a comprehensive solution designed to restore the cooling system on Yamaha 2-stroke outboard motors from 25 to 70 HP (1984–2005). The kit provides all necessary components for a complete water pump assembly rebuild, ensuring your engine maintains proper operating temperatures.
It serves as a direct interchange for several Yamaha part numbers, including 663-W0078-01, 663-W0078-A0, 6H3-W0078-02-00, and 6H3-W0078-A0-00.
- Engineered for direct OEM replacement installation.
- Maintains proper cooling water circulation for outboard motors.
- Includes impeller, gaskets, plates, and hardware for a full service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 663-W0078-01 |
| Yamaha | 663-W0078-A0 |
| Yamaha | 6H3-W0078-02-00 |
| Yamaha | 6H3-W0078-A0-00 |
| Yamaha | 6H4-W0078-00 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit fits a wide range of Yamaha 2-stroke outboards. Please verify your specific model and year against the compatibility list.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | C-55 | 55 | 2-Stroke | 1991–1995 | 663-W0078-01, 663-W0078-A0 | |
| Yamaha | CV-55 | 55 | 2-Stroke | 1989 | 663-W0078-01, 663-W0078-A0 | |
| Yamaha | C-60 | 60 | 2-Stroke | 1997–2001 | 6H3-W0078-02-00 | |
| Yamaha | C-70 | 70 | 2-Stroke | 2000–2001 | 6H3-W0078-02-00 | |
| Yamaha | P-60 | 60 | 2-Stroke | 1997–1999 | 6H3-W0078-02-00 | |
| Yamaha | T-50 | 50 | 2-Stroke | 1997–2001, 2003, 2005 | 6H3-W0078-02-00 | |
| Yamaha | T-60 | 60 | 2-Stroke | 2003–2005 | 6H3-W0078-02-00 | |
| Yamaha | 60 | 60 | 2-Stroke | 2003 | 6H3-W0078-02-00 | |
| Yamaha | 70 | 70 | 2-Stroke | 1997–2003 | 6H3-W0078-02-00 | |
| Yamaha | T50 | 50 | 2-Stroke | 1996 | 6H3-W0078-A0-00 | |
| Yamaha | C55 (Drive 2) | 55 | 2-Stroke | 1991–1994 | 6H3-W0078-A0-00 | |
| Yamaha | CV55 (Drive 2) | 55 | 2-Stroke | 1989 | 6H3-W0078-A0-00 | |
| Yamaha | P60 | 60 | 2-Stroke | 1991 | 6H3-W0078-A0-00 | |
| Yamaha | 60 | 60 | 2-Stroke | 1984–1991 | 6H3-W0078-A0-00 | |
| Yamaha | 40 | 40 | 2-Stroke | 1984–1994 | 6H4-W0078-00 | |
| Yamaha | 50 | 50 | 2-Stroke | 1986–1994 | 6H4-W0078-00 | |
| Yamaha | Pro 50 | 50 | 2-Stroke | 1991–1994 | 6H4-W0078-00 |
Technical Specs
- Product Type
- Water Pump Impeller Kit
- Installation
- Direct OEM replacement
- Other Technical Attributes
- Maintains proper cooling water circulation for outboard motors
What’s in the Box
- 1 x Cartridge Insert (663-44322-00-00)
- 1 x Impeller (6H3-44352-00-00)
- 1 x Water Pump Gasket (663-44315-A0-00)
- 1 x Cartridge Outer Plate (663-44323-00-00)
- 1 x Cartridge Gasket (663-44324-A0-00)
- 2 x Bolts (97095-08055-00)
- 2 x Bolts (97095-08045-00)
- 1 x Water Seal Damper 2 (663-44366-00-00)
- 1 x Woodruff Key (90280-03M03-00)
Installation Notes
- Disconnect the negative battery cable before beginning work.
- Remove the lower unit (gearcase) from the outboard’s midsection.
- Unbolt and carefully remove the existing water pump housing. Note the orientation of the bolts.
- Inspect the housing assembly for cracks, scoring, or warping. Clean all gasket surfaces thoroughly.
- Remove the old impeller, woodruff key, wear plate, gaskets, and seals.
- Install the new water seal damper and cartridge gasket onto the clean housing plate.
- Place the new woodruff key onto the flat spot on the driveshaft.
- Slide the new impeller down the driveshaft, aligning its keyway with the key. Rotate the driveshaft clockwise to help seat the impeller vanes correctly.
- Install the new cartridge insert and outer plate over the impeller.
- Apply the new water pump gasket and reinstall the housing using the new bolts. Tighten bolts to the manufacturer's specified torque in a crisscross pattern.
- Reinstall the lower unit, ensuring the driveshaft and water tube align correctly.
- Reconnect the battery, start the engine in water, and confirm a steady stream of water from the tell-tale outlet.
Troubleshooting & FAQ
What are the signs of a failing water pump impeller?
Common signs include a weak or intermittent water stream from the "tell-tale" outlet, engine overheating alarms, and in severe cases, steam from the exhaust. Reduced top-end speed or engine performance can also indicate poor cooling.
How often should I replace my outboard's impeller?
As a general preventative maintenance rule, it is recommended to replace the impeller every 1-2 years or every 100-200 hours of operation, whichever comes first. Usage in saltwater or sandy/silty conditions may require more frequent changes.
Does this kit include the water pump housing?
This kit includes the internal components required for a rebuild (impeller, gaskets, plates, etc.) but does not include the main upper or lower water pump housing. You will typically reuse your existing housing if it is not cracked, warped, or excessively scored.
What is the difference between the listed OEM part numbers like 663-W0078-01 and 6H3-W0078-A0-00?
These different numbers often represent superseded parts. Manufacturers update parts over time for various reasons, creating a chain where a newer number replaces an older one. This aftermarket kit is designed to be-a cross-reference for all listed equivalents.
Is this a complete kit for the job?
Yes, this kit is assembled to include all the common wear items needed for a standard water pump service. You receive the impeller, gaskets, plates, damper seal, key, and new bolts as pictured and listed.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in 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.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
