Water Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Replaces 66T-W0078-00)
Water Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Replaces 66T-W0078-00) is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Rep...
Water Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Replaces 66T-W0078-00) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Replaces 66T-W0078-00) provides a comprehensive solution for servicing the water pump on Yamaha T25 HP, F30 HP, and F40 HP models manufactured between 2000 and 2005. It is engineered to restore your engine’s cooling system to its original performance.
This kit serves as a direct cross-reference for Yamaha part numbers 66T-W0078-00 and 66T-W0078-01-00, as well as Sierra aftermarket equivalents 18-3440 and 18-3413.
- Engineered for direct-fit installation, matching OEM specifications for a reliable repair.
- Features a durable, 6-blade impeller designed for optimal water flow and cooling efficiency.
- Includes all necessary gaskets, seals, and hardware for a complete and professional service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 66T-W0078-00 |
| Yamaha | 66T-W0078-01-00 |
| Sierra | 18-3440 |
| Sierra | 18-3413 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yamaha owners, please verify your engine's model, horsepower, and year range against this list to ensure an exact match.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | T25 | 25 | 4-Stroke | 2001–2006, 2009 | 66T-W0078-00 | |
| Yamaha | F30 | 30 | 4-Stroke | 2001–2005 | 66T-W0078-00 | |
| Yamaha | F40 | 40 | 4-Stroke | 2000–2008 | 66T-W0078-00 | |
| Yamaha | 40XMH | 40 | 2-Stroke | 2000–2005 | 66T-W0078-00 | |
| Yamaha | 40XE | 40 | 2-Stroke | 2000–2005 | 66T-W0078-00 |
Technical Specs
- Product Type
- Water Pump Impeller Kit
- Installation
- Direct Replacement
- Dimensions
- Impeller Diameter: 52 mm, Width: 19 mm, Shaft Size: 16 mm
- Fitting Type
- Keyway
- Number of Blades
- 6
What’s in the Box
- 1 x Cartridge Insert (63D-44322-00-00)
- 1 x Cartridge Outer Plate (66T-44323-00-00)
- 1 x O-Ring (93210-59MG7-00)
- 1 x Water Pump Gasket (63D-44316-00-00)
- 1 x Woodruff Key (90280-03M03-00)
- 1 x Impeller (6H4-44352-02-00)
- 4 x Bolts, With Washer (90119-08M15-00)
- 1 x Water Seal Damper 2 (663-44366-00-00)
- 1 x Pump Housing Cover (63D-44312-00-00)
Installation Notes
- Disconnect the battery and shift the outboard into neutral. Remove the lower unit mounting bolts.
- Carefully separate the lower unit from the upper housing, being mindful of the shift shaft.
- With the lower unit on a workbench, unbolt and remove the water pump housing cover.
- Remove the old impeller, key, wear plate, and gaskets. Note the rotational direction of the old impeller blades.
- Thoroughly clean all mating surfaces, removing any old gasket residue or corrosion.
- Install the new gasket, wear plate, and insert cartridge. Lightly grease the interior surfaces.
- Place the woodruff key in its slot on the driveshaft and slide the new impeller on. Turn the driveshaft clockwise to orient the blades correctly.
- Install the new O-ring and housing cover, then tighten the bolts to the manufacturer’s specified torque.
- Realign and attach the lower unit to the upper housing, ensuring the driveshaft, shift shaft, and water tube are correctly seated.
- Once assembled, test the engine using a flush-pro or in water to confirm a strong, steady stream from the tell-tale port.
Troubleshooting & FAQ
How do I know if this kit fits my Yamaha outboard?
This kit is designed for specific Yamaha models including the T25 (2001–2006, 2009), F30 (2001–2005), and F40 (2000–2008). To ensure a perfect match, please cross-reference your engine's exact model and year with the compatibility table provided.
What are the signs of a failing water pump impeller?
Common symptoms include the engine overheating at idle, a weak or inconsistent water stream from the tell-tale outlet, and a melted pump housing. Upon inspection, a worn impeller may have brittle, cracked, or deformed blades.
How often should the water pump impeller be replaced?
For preventative maintenance, we recommend replacing the impeller every one to two years, or every 100-200 hours of operation. More frequent replacement may be necessary if operating in sandy, silty, or saltwater conditions.
Is this a complete kit for a water pump service?
Yes, this is a comprehensive kit containing the impeller, housing, cover, gaskets, plates, key, and all necessary seals and hardware for a standard water pump replacement.
Do I need special tools for installation?
Standard workshop tools like a socket set, screwdrivers, and a torque wrench are required. No other highly specialized tools are typically necessary for this service.
Can I install the impeller with blades bent the wrong way?
The impeller blades must curve in the correct direction to pump water effectively. During installation, always turn the driveshaft clockwise as you slide the housing down to ensure the blades are properly oriented.
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.
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