Water Pump Impeller Kit – Fits Yamaha F40/F70 4-Stroke (Replaces 6CJ-W0078-00-00)
Water Pump Impeller Kit – Fits Yamaha F40/F70 4-Stroke (Replaces 6CJ-W0078-00-00) 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 F40/F70 4-Stroke (Replaces 6C...
Water Pump Impeller Kit – Fits Yamaha F40/F70 4-Stroke (Replaces 6CJ-W0078-00-00) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit – Fits Yamaha F40/F70 4-Stroke (Replaces 6CJ-W0078-00-00) contains all necessary components to service the water pump assembly on compatible Yamaha 4-stroke outboard motors. It includes the impeller, gaskets, seals, plates, and hardware for a complete overhaul.
This kit directly replaces Yamaha 6CJ-W0078-00-00, 6CJ-W0078-01-00; Sierra 18-3494; and Quicksilver 8M6012800.
- Designed for direct OEM-level replacement and installation.
- Features stainless steel components and a durable rubber impeller for longevity.
- Engineered to provide higher cooling flow to protect the engine from overheating.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By |
|---|---|---|
| Yamaha | 6CJ-W0078-00-00 | 6CJ-W0078-01-00 |
| Yamaha | 6CJ-W0078-01-00 | |
| Sierra | 18-3494 | |
| Quicksilver | 8M6012800 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is confirmed for Yamaha F70 models and listed by some vendors for F40 models. Verify your specific OEM part number before ordering.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Yamaha | F70 | 70 | 4-Stroke | 6CJ-W0078-00-00 | Superseded by 6CJ-W0078-01-00 |
| Yamaha | F40 | 40 | 4-Stroke | 6CJ-W0078-00-00 | Direct replacement |
Technical Specs
- Product Type
- Water Pump Repair Kit
- Installation
- Direct OEM replacement
- Housing Material
- Stainless steel components with rubber impeller
- Package Type
- Complete kit with all components
- Primary Components
- Impeller, housing cover, gaskets, seals
- Other Technical Attributes
- Designed to provide higher cooling flow to protect engine
What’s in the Box
- 1 x Insert, Cartridge (63D-44322-00-00)
- 1 x Gasket, Water Pump (6CJ-44315-00-00)
- 1 x Cover, Pump Housing (63D-44312-00-00)
- 1 x Damper, Water Seal 2 (663-44366-00-00)
- 1 x Impeller (6H3-44352-00-00)
- 1 x Key, Woodruff (90280-03M03-00)
- 2 x Oil Seal (93101-23070-00)
- 1 x O-Ring (93210-46044-00)
- 1 x Gasket, Water Pump (6CJ-44316-00-00)
- 1 x Outer Plate, Cartridge (6CJ-44323-00-00)
- 1 x Gasket, Cartridge (6CJ-44324-00-00)
- 2 x Pin, Dowel (93604-10M03-00)
- 2 x Bolt, With Washer (90119-08M33-00)
- 2 x Bolt, With Washer (90119-08M14-00)
Installation Notes
- Disconnect the battery and remove the engine cover.
- Place the outboard in neutral and drain the gearcase oil from the lower unit.
- Remove the bolts securing the lower unit to the upper casing and carefully lower it.
- Unbolt and remove the water pump housing to access the old impeller and components.
- Clean all mating surfaces thoroughly, removing any old gasket material or sealant.
- Install the new Woodruff key, impeller, seals, and gaskets as provided in the kit. Ensure the impeller vanes are oriented correctly.
- Reassemble the pump housing, torquing bolts to manufacturer specifications.
- Reinstall the lower unit, ensuring the driveshaft and water tube align correctly.
- Refill the gearcase with fresh oil before starting the engine.
Troubleshooting & FAQ
What are the signs of a failing water pump impeller?
Common symptoms include the engine overheating at idle or low speeds, a weak or non-existent stream of water from the tell-tale outlet, and a dry, brittle, or cracked appearance on the old impeller upon inspection.
How often should I replace the impeller?
For optimal reliability, most marine mechanics recommend replacing the water pump impeller and gaskets every 1-2 years or every 100-200 hours of operation, whichever comes first.
Does this kit fit my Yamaha F40?
This kit is listed as compatible with certain Yamaha F40 4-Stroke models by multiple aftermarket sources. However, as year ranges are not confirmed, we strongly recommend verifying the OEM part number (6CJ-W0078-00-00) for your specific engine before purchasing.
What is the difference between part number 6CJ-W0078-00-00 and 6CJ-W0078-01-00?
The part number 6CJ-W0078-01-00 superseded (replaced) 6CJ-W0078-00-00. They are functionally identical, and this kit serves as a replacement for both OEM versions.
Can I reuse my old gaskets or seals?
No. Always use the new gaskets and seals included in the kit to ensure a watertight and reliable repair. Reusing old components can lead to leaks and premature pump failure.
Is the pump housing included?
This kit includes the pump housing cover (63D-44312-00-00) and other essential wear items like the cartridge insert and outer plate, but not the main lower housing body.
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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