Water Pump Impeller Kit – Fits Yamaha 50–70 HP (Replaces 6H3-W0078-02-00, 6H3-W0078-A0-00) – 2 Mounting Screws Short
Water Pump Impeller Kit – Fits Yamaha 50–70 HP (Replaces 6H3-W0078-02-00, 6H3-W0078-A0-00) – 2 Mounting Screws Short 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 Impeller Kit – Fits Yamaha 50–70 HP (Replaces 6H3-W0078-02-00, 6H3-W0078-A0-00) – 2 Mounting Screws Short is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Water Pump Impeller Kit is designed for servicing compatible Yamaha 2-Stroke 60–70 HP and 4-Stroke T50, FT50, T60, and FT60 outboard motors. The package corresponds to a standard water pump service kit, but contains two fewer mounting screws than the standard configuration.
The kit is listed as a replacement for Yamaha part numbers 6H3-W0078-00-00, 6H3-W0078-A0-00, 6H3-W0078-02-00, and 6H3-44311-00-00, as well as Sierra aftermarket references 18-3461 and 18-3466. Confirm the part number, engine model, year, horsepower, and stroke before ordering.
- Designed as a direct-replacement water pump service kit for listed applications.
- Includes the housing, impeller, insert cup, wear plate, gaskets, O-ring, key, and limited mounting hardware.
- Features a neoprene impeller, nylon PA66 housing, and SS316 stainless-steel insert cup.
- Important package note: this package is short two mounting screws compared with the standard kit configuration.
Part Number Matrix
Use the following references to compare the replacement kit with the original water pump components.
| Brand | Part Number |
|---|---|
| Yamaha | 6H3-W0078-00-00 |
| Yamaha | 6H3-W0078-A0-00 |
| Yamaha | 6H3-W0078-02-00 |
| Yamaha | 6H3-44311-00-00 |
| Sierra | 18-3461 |
| Sierra | 18-3466 |
Engine & Model Compatibility
Confirm the exact engine model, rated horsepower, stroke, and production year before installation. The following applications are associated with the listed replacement references.
Yamaha 2-Stroke Models
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Yamaha | 60F | 60 | 2-Stroke | 1997–2003 | 6H3-W0078-02-00 |
| Yamaha | P60 | 60 | 2-Stroke | 1992–1999 | 6H3-W0078-02-00 |
| Yamaha | E60 | 60 | 2-Stroke | 1995–1996 | 6H3-W0078-02-00 |
| Yamaha | C60 | 60 | 2-Stroke | 1996–2001 | 6H3-W0078-02-00 |
| Yamaha | 70 | 70 | 2-Stroke | 1992–2003 | 6H3-W0078-02-00 |
| Yamaha | 70B | 70 | 2-Stroke | 1997–2003 | 6H3-W0078-02-00 |
| Yamaha | C70 | 70 | 2-Stroke | 2000–2001 | 6H3-W0078-02-00 |
Yamaha 4-Stroke Models
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Yamaha | T50 | 50 | 4-Stroke | 1997–2010 | 6H3-W0078-02-00 |
| Yamaha | FT50B | 50 | 4-Stroke | 1997–2002 | 6H3-W0078-02-00 |
| Yamaha | FT50C | 50 | 4-Stroke | 2003–2007 | 6H3-W0078-02-00 |
| Yamaha | FT50G | 50 | 4-Stroke | 2005–2012 | 6H3-W0078-02-00 |
| Yamaha | FT50J | 50 | 4-Stroke | 2013–UP | 6H3-W0078-02-00 |
| Yamaha | T60 | 60 | 4-Stroke | 2003–2010 | 6H3-W0078-02-00 |
| Yamaha | FT60B | 60 | 4-Stroke | 2003–2006 | 6H3-W0078-02-00 |
| Yamaha | FT60D | 60 | 4-Stroke | 2005–2012 | 6H3-W0078-02-00 |
| Yamaha | FT60G | 60 | 4-Stroke | 2013–UP | 6H3-W0078-02-00 |
Technical Specs
- Product Type
- Water pump impeller kit with housing
- Installation
- Direct replacement
- Housing Material
- Nylon PA66 plastic
- Housing Color
- Black
- Impeller Material
- Neoprene
- Insert Cup Material
- SS316 stainless steel
- Weight
- 0.65 lb (0.29 kg)
- Package Condition
- Two mounting screws short compared with the standard kit configuration
What’s in the Box
- 1 x Water pump gasket, 688-44316-01-00 / 688-44316-A0-00
- 1 x Water pump gasket, 6H2-44315-00-00 / 6H2-44315-A0-00
- 1 x Outer plate gasket, 6H2-44324-00-00 / 6H2-44324-A0-00
- 1 x Wear plate, 6H3-44323-00-00
- 1 x Impeller, 6H2-44352-00-00
- 1 x Impeller key, 90280-03M03-00 / 90280-03M07-00
- 1 x Insert cup, 663-44322-00-00
- 1 x O-ring, 93210-46044-00
- 1 x Water pump housing, 6H2-44311-00-00
- 2 x Mounting bolts with washers total; this package is short two screws compared with the standard configuration. The applicable bolt references are 90119-08M14-00 and 90119-08M33-00.
Installation Notes
- Disconnect the negative battery cable and remove the propeller.
- Place a drain pan under the lower unit and remove the gear-oil drain and fill plugs to drain the fluid.
- Remove the bolts securing the lower unit to the upper engine housing, then carefully separate the two sections.
- Remove the old water pump housing to access the impeller, wear plate, and gaskets. Record the orientation of all parts before removal.
- Clean all mating surfaces and remove old gasket material, dirt, and debris.
- Install the new wear plate, gaskets, impeller key, and impeller. Make sure the key securely locks the impeller to the driveshaft.
- Apply a light coat of suitable marine grease to the inside of the housing and to the impeller.
- Install the insert cup and O-ring in the correct position.
- Lower the housing over the impeller while turning the driveshaft clockwise so the impeller vanes seat correctly.
- Secure the housing using the available mounting hardware. Because this package is short two screws, verify that all required fasteners are available before beginning installation.
- Reassemble the lower unit and refill the gearcase with the correct marine gear oil to the specified level.
- Reconnect the battery, start the engine in water, and check immediately for a strong, steady tell-tale water stream.
Troubleshooting & FAQ
How do I confirm that this kit fits my engine?
Compare your engine’s exact model, horsepower, stroke, and year with the compatibility tables. Also compare the part number on your original water pump components with the references in the Part Number Matrix. If any identifying detail differs, confirm fitment before ordering.
What are the signs of a worn water pump impeller?
Common symptoms include a weak or intermittent tell-tale stream, overheating alarms, steam from the exhaust, or reduced cooling performance, particularly at higher RPM.
How often should an outboard impeller be replaced?
Inspect the impeller regularly and replace it according to the engine manufacturer’s service schedule. More frequent service may be necessary for engines used in saltwater, sandy water, or water containing heavy sediment.
What does this kit include?
The kit includes the water pump housing, impeller, insert cup, wear plate, gaskets, O-ring, impeller key, and limited mounting hardware. This specific package contains two fewer mounting screws than the standard configuration.
Is this an OEM part?
This is an aftermarket replacement kit and is not manufactured by Yamaha or Sierra. Yamaha and Sierra names and part numbers are used only to identify compatible applications and replacement references.
Can I install the kit with the included mounting hardware?
Check the fasteners against the original water pump assembly before installation. This package is short two mounting screws compared with the standard configuration, so obtain any missing fasteners before reassembly and use the correct size and specification for your engine.
Safety & Important Information
- Verify the engine model, year, horsepower, stroke, and original component references before purchasing.
- Do not operate the engine if required mounting hardware is missing, damaged, or incorrectly sized.
- Run the outboard only in water or with an appropriate flushing device, and check for a steady tell-tale stream after installation.
- Professional installation by a qualified marine mechanic is recommended.
- This is an aftermarket replacement product, not an Original Equipment Manufacturer component.
About Sea Sierra
- Pro-Grade Standards — We supply marine replacement parts selected for dependable fit and service use.
- Fast Global Fulfillment — Standard delivery options are available for most regions, with transit times depending on destination and shipping method.
- Manufacturer-Direct Value — We work with manufacturing partners to provide replacement parts at competitive value.
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