Water Pump Repair Kit – Fits Yamaha 50-70 HP Outboards (Replaces 6H3-W0078-02-00, 18-3465)
Water Pump Repair Kit – Fits Yamaha 50-70 HP Outboards (Replaces 6H3-W0078-02-00, 18-3465) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Water Pump Repair Kit – Fits Yamaha 50-70 HP Outboards (Replaces 6H...
Water Pump Repair Kit – Fits Yamaha 50-70 HP Outboards (Replaces 6H3-W0078-02-00, 18-3465) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Repair Kit is engineered for cooling system maintenance on a range of Yamaha outboards. It is designed to fit specific Yamaha 2-Stroke models from 60 HP to 70 HP (1997–2003) and 4-Stroke T50 & T60 High Thrust models (1996–2023), ensuring reliable performance and engine protection.
This kit serves as a direct replacement for Yamaha part number 6H3-W0078-02-00 and Sierra 18-3465.
- Designed for comprehensive cooling system maintenance.
- Installs in the lower unit gearcase.
- Includes key components like impeller, gaskets, and hardware for a complete service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number |
|---|---|
| Yamaha | 6H3-W0078-02-00 |
| Sierra | 18-3465 |
Engine & Model Compatibility
Confirm your engine model and year in the table below to ensure accurate fitment.
This kit is verified for compatibility with the following Yamaha outboard motors.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | T50 | 50 | 4-Stroke | 1996–2023 | 6H3-W0078-02-00 | High Thrust models |
| Yamaha | T60 | 60 | 4-Stroke | 1997–2023 | 6H3-W0078-02-00 | High Thrust models |
| Yamaha | 60 | 60 | 2-Stroke | 1997–2003 | 6H3-W0078-02-00 | |
| Yamaha | C60 | 60 | 2-Stroke | 1997–2001 | 6H3-W0078-02-00 | Commercial models |
| Yamaha | P60 | 60 | 2-Stroke | 1997–1999 | 6H3-W0078-02-00 | |
| Yamaha | 70 | 70 | 2-Stroke | 1997–2003 | 6H3-W0078-02-00 | |
| Yamaha | C70 | 70 | 2-Stroke | 1997–2003 | 6H3-W0078-02-00 | Commercial models |
Technical Specs
- Product Type
- Water Pump Repair Kit
- Installation
- Lower Unit / Gearcase
- Other Technical Attributes
- Designed for cooling system maintenance
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 1 (6H3-44315-A0-00)
- 1 x Cartridge Outer Plate (6H3-44323-00-00)
- 1 x Cartridge Gasket (6H3-44324-A0-00)
- 1 x Water Pump Gasket 2 (688-44316-A0-00)
- 1 x O-Ring (93210-46044-00)
- 2 x Bolts, With Washer (90119-08M14-00)
- 2 x Bolts, With Washer (90119-08M33-00)
- 1 x Woodruff Key (90280-03M03-00)
Installation Notes
- Disconnect the battery and shift the outboard into neutral.
- Remove the lower unit (gearcase) by unfastening the mounting bolts located above the anti-cavitation plate.
- Place the lower unit on a suitable workbench. Locate and unbolt the water pump housing.
- Remove the old impeller, gaskets, wear plate, and housing components. Clean all surfaces thoroughly.
- Install the new gasket, wear plate, and Woodruff key on the driveshaft.
- Slide the new impeller onto the driveshaft, rotating it clockwise to align the blades.
- Install the new housing, cartridge insert, and O-rings as supplied in the kit.
- Securely fasten the water pump housing with the new bolts, applying recommended torque settings.
- Reinstall the lower unit, ensuring the water tube and driveshaft are properly aligned. Secure the mounting bolts.
- Reconnect the battery and test the engine with a reliable water source to verify proper cooling system function.
Troubleshooting & FAQ
How do I know if this kit fits my Yamaha outboard?
This kit is designed for specific Yamaha engines. Verify your complete model number and year against the compatibility table provided on this page. Do not rely on horsepower alone. Cross-referencing your old part number with the ones listed in our Part Number Matrix (6H3-W0078-02-00) is the most reliable method.
What are the signs of a failing water pump?
Common symptoms include the engine overheating at idle or low speeds, a weak or inconsistent "tell-tale" water stream, or a discolored/melted water pump housing found during inspection. Gradual loss of cooling efficiency is the primary indicator.
How often should I replace my water pump impeller and kit components?
As a best practice for preventative maintenance, outboard water pump impellers should be inspected annually and replaced every 1-2 years or 100-200 hours of operation, depending on usage conditions (e.g., more frequently in sandy or saltwater environments). Replacing the full kit is recommended to ensure all wear components are new.
Does this kit include everything I need for the job?
Yes, this is a comprehensive repair kit that includes the impeller, housing insert, gaskets, plate, O-ring, Woodruff key, and the necessary installation bolts as listed in the "What's in the Box" section. You will not need to purchase these core components separately.
Is it difficult to install this kit myself?
Installation is suitable for individuals with moderate mechanical skill and the proper tools. The process involves removing the lower unit (gearcase). If you are unfamiliar with this procedure, we recommend consulting a service manual for your specific engine or hiring a professional marine mechanic.
precludedWhy is a consistent water stream from the tell-tale important?
The "tell-tale" stream is a visual indicator that the water pump is successfully circulating water through the engine's cooling passages. A strong, steady stream indicates the pump is functioning correctly. A weak, intermittent, or non-existent stream signals a problem that requires immediate attention to prevent overheating.
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 and specifications against 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 quality control.
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