Water Pump Impeller Kit – Fits Yamaha T25-F40 (Replaces 66T-W0078-00-00, 18-3413)
Water Pump Impeller Kit – Fits Yamaha T25-F40 (Replaces 66T-W0078-00-00, 18-3413) 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 Kit – Fits Yamaha T25-F40 (Replaces 66T-W0078-0...
Water Pump Impeller Kit – Fits Yamaha T25-F40 (Replaces 66T-W0078-00-00, 18-3413) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit – Fits Yamaha T25, F30, F40 (2000-2009) (Replaces 66T-W0078-00-00) provides all necessary components for a complete water pump service. It is designed for a precise fit on select Yamaha 4-stroke engines including the T25 (2001-2019), F30 (2001-2005), and F40 (2000-2008), as well as 2-stroke models 40X, 40XWT, and E40X from 1998 onward.
This kit serves as a direct interchange for Yamaha part numbers 66T-W0078-00-00 and 66T-W0078-01-00, Sierra 18-3413 and 18-3440, and other aftermarket equivalents.
- Engineered for direct OEM-level installation.
- Features a durable 6-blade neoprene impeller for reliable cooling performance.
- All components are manufactured in an ISO9002 certified factory to ensure quality and consistency.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number |
|---|---|
| Yamaha | 66T-W0078-00-00 |
| Yamaha | 66T-W0078-01-00 |
| Sierra | 18-3413 |
| Sierra | 18-3440 |
| Aftermarket | MAL9-48610 |
| Aftermarket | AM66T-W0078-00 |
Engine & Model Compatibility
Confirm your engine model and year in the table below.
This kit is verified for a wide range of Yamaha outboard engines. Please check your specific model and year against the list to ensure correct fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | FT25B | 25 | 4-Stroke | 2000–2009 | 66T-W0078-00-00 | |
| Yamaha | FT25F | 25 | 4-Stroke | 2009+ | 66T-W0078-00-00 | |
| Yamaha | T25 | 25 | 4-Stroke | 2001–2006 | 66T-W0078-00-00 | |
| Yamaha | T25TLR | 25 | 4-Stroke | 2001–2006 | 66T-W0078-00-00 | |
| Yamaha | T25LA | 25 | 4-Stroke | 2009–2016 | 66T-W0078-00-00 | |
| Yamaha | F30A | 30 | 4-Stroke | 2001–2009 | 66T-W0078-00-00 | |
| Yamaha | F30TLR | 30 | 4-Stroke | 2001–2005 | 66T-W0078-00-00 | |
| Yamaha | F40B | 40 | 4-Stroke | 2000–2009 | 66T-W0078-00-00 | |
| Yamaha | F40BEJR | 40 | 4-Stroke | 2004–2007 | 66T-W0078-00-00 | |
| Yamaha | F40BMJH | 40 | 4-Stroke | 2004–2007 | 66T-W0078-00-00 | |
| Yamaha | F40BMLH | 40 | 4-Stroke | 2004–2008 | 66T-W0078-00-00 | |
| Yamaha | F40BTLR | 40 | 4-Stroke | 2004–2008 | 66T-W0078-00-00 | |
| Yamaha | F40EJR | 40 | 4-Stroke | 2004–2006 | 66T-W0078-00-00 | |
| Yamaha | F40EJRB | 40 | 4-Stroke | 2003 | 66T-W0078-00-00 | |
| Yamaha | F40EJRC | 40 | 4-Stroke | 2004 | 66T-W0078-00-00 | |
| Yamaha | F40EJRD | 40 | 4-Stroke | 2005 | 66T-W0078-00-00 | |
| Yamaha | F40ESRA | 40 | 4-Stroke | 2002 | 66T-W0078-00-00 | |
| Yamaha | F40ESRB | 40 | 4-Stroke | 2003 | 66T-W0078-00-00 | |
| Yamaha | F40ESRY | 40 | 4-Stroke | 2000 | 66T-W0078-00-00 | |
| Yamaha | F40ESRZ | 40 | 4-Stroke | 2001 | 66T-W0078-00-00 | |
| Yamaha | F40MJH | 40 | 4-Stroke | 2002–2006 | 66T-W0078-00-00 | |
| Yamaha | F40MLH | 40 | 4-Stroke | 2000–2006 | 66T-W0078-00-00 | |
| Yamaha | F40MSH | 40 | 4-Stroke | 2000–2006 | 66T-W0078-00-00 | |
| Yamaha | F40TLR | 40 | 4-Stroke | 2000–2006 | 66T-W0078-00-00 | |
| Yamaha | 40X | 40 | 2-Stroke | from 1998 | 66T-W0078-00-00 | |
| Yamaha | 40XWT | 40 | 2-Stroke | from 1998 | 66T-W0078-00-00 | |
| Yamaha | E40X | 40 | 2-Stroke | from 1998 | 66T-W0078-00-00 |
Technical Specs
- Product Type
- Water Pump Impeller Kit
- Installation
- Direct OEM Replacement
- Impeller Material
- Neoprene Rubber
- Impeller Design
- 6-Blade
- Shaft Size
- 16 mm
- Impeller Diameter
- 52 mm
- Impeller Width
- 19 mm
- Keyway
- Yes
- Manufacturing Standards
- ISO9002 Certified Factory
What’s in the Box
- 1 x Impeller (6H4-44352-02-00)
- 1 x Cartridge Insert (63D-44322-00-00)
- 1 x Cartridge Outer Plate (66T-44323-00-00)
- 1 x Pump Housing Cover (63D-44312-00-00)
- 1 x Water Pump Gasket (63D-44316-00-00)
- 1 x Water Seal Damper (663-44366-00-00)
- 1 x Woodruff Key (90280-03M03-00)
- 1 x O-Ring (93210-59MG7-00)
- 4 x Bolts with Washer (90119-08M15-00)
Installation Notes
- Disconnect the battery and ignition-kill switch lanyard.
- Shift the outboard into forward gear to simplify driveshaft re-engagement.
- Remove the lower unit (gearcase) from the outboard's midsection.
- Unbolt and remove the existing water pump housing cover and housing.
- Slide the old impeller off the driveshaft, removing the Woodruff key.
- Inspect the housing and plate for grooves or damage. Clean all mating surfaces thoroughly.
- Install the new key, gasket, and impeller. Rotate the driveshaft clockwise while lowering the housing to fold the impeller blades correctly.
- Install the new gaskets, seals, and O-rings from the kit.
- Lightly grease the bolt threads and torque them to the manufacturer's specification in a crisscross pattern.
- Reinstall the lower unit, ensuring the driveshaft, shift shaft, and water tube align correctly.
- Once assembled, test the engine with a water supply, confirming a steady stream of water from the tell-tale port.
Troubleshooting & FAQ
How do I know if this kit fits my engine?
The surest way is to check the part number stamped on your original components against the numbers in our Part Number Matrix. Additionally, cross-reference your exact engine model and year with our compatibility table. Do not rely on HP rating alone.
What are the signs of a failing water pump impeller?
Common symptoms include a weak or intermittent water stream from the "tell-tale" port, engine overheating alarms, and in severe cases, steam from the exhaust. Reduced cooling efficiency can cause significant engine damage if not addressed.
How often should I replace the water pump impeller?
As a preventative maintenance item, it is best practice to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of operation, whichever comes first. Usage in saltwater or silty/sandy conditions may require more frequent replacement.
Is the entire water pump housing included in this kit?
This kit includes the essential service components: the impeller, gaskets, O-rings, plates, and a new pump housing cover (63D-44312-00-00). It does not include the main pump housing body. You should reuse your existing housing if it is in good condition, free of scoring or corrosion.
What's the difference between this impeller and the OEM one?
Our impeller is designed to match the OEM specifications for fit, material composition (durable neoprene), and blade count (6). It provides equivalent cooling performance and durability under normal operating conditions.
Is this a complete kit for the job?
Yes, this kit is designed to be a comprehensive service package. It includes all necessary gaskets, seals, the impeller, key, plates, and mounting hardware, saving you from having to source each part individually.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. The parts are manufactured in an ISO 9002 facility and batch-inspected for consistency and quality.
Shipping speed & cost
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options will appear at checkout where available for your location.
Warranty & returns
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 and specifications against your original part before purchase. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement part, not an OEM component.
- Professional installation is highly recommended for safety and optimal performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and thoroughly tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions, with typical transit times of 5–15 days.
- Manufacturer-Direct Value — Our model provides fair pricing without compromising on materials or quality control.
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