Water Pump Impeller Kit – Fits Yamaha 2-Stroke 40HP (Replaces 6F5-W0078-A0-00, 679-W0078-A1-00)
Water Pump Impeller Kit – Fits Yamaha 2-Stroke 40HP (Replaces 6F5-W0078-A0-00, 679-W0078-A1-00) 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 2-Stroke 40HP (Replaces 6F5-W...
Water Pump Impeller Kit – Fits Yamaha 2-Stroke 40HP (Replaces 6F5-W0078-A0-00, 679-W0078-A1-00) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit – Fits Yamaha 2-Stroke 40HP (Replaces 6F5-W0078-A0-00, 679-W0078-A1-00) is designed for Yamaha 2-stroke 40HP outboard engines produced from 1990–1997, including CV40 and C40 models. It contains all necessary components for a complete water pump service, ensuring your cooling system functions reliably.
This kit serves as a direct replacement for Yamaha OEM part numbers 6F5-W0078-A0-00 and 679-W0078-A1-00, as well as Sierra equivalents 18-3374, 18-3397, and 18-3398.
- Engineered for direct OEM-replacement installation.
- Features a housing made from marine-grade alloy that matches original specifications.
- Includes all essential gaskets, seals, and hardware for a full rebuild.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 6F5-W0078-A0-00 |
| Yamaha | 679-W0078-A1-00 |
| Sierra | 18-3374 |
| Sierra | 18-3397 |
| Sierra | 18-3398 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is compatible with a range of Yamaha 40HP 2-stroke outboard models. Please verify your specific model and year before purchasing.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Yamaha | CV40ELD | 40 | 2-Stroke | 1990 | 6F5-W0078-A0-00 |
| Yamaha | CV40EL | 40 | 2-Stroke | 1990 | 6F5-W0078-A0-00 |
| Yamaha | C40ELR | 40 | 2-Stroke | 1991–1997 | 679-W0078-A1-00 |
| Yamaha | C40MLH | 40 | 2-Stroke | 1994–1995 | 679-W0078-A1-00 |
| Yamaha | C40MSH | 40 | 2-Stroke | 1992–1997 | 679-W0078-A1-00 |
| Yamaha | C40PLR | 40 | 2-Stroke | 1992–1997 | 679-W0078-A1-00 |
| Yamaha | C40ESH | 40 | 2-Stroke | 1997 | 679-W0078-A1-00 |
| Yamaha | C40MSHU | 40 | 2-Stroke | 1996 | 679-W0078-A1-00 |
| Yamaha | C40MSHT | 40 | 2-Stroke | 1995 | 679-W0078-A1-00 |
| Yamaha | C40ELRU | 40 | 2-Stroke | 1996 | 679-W0078-A1-00 |
| Yamaha | C40PLRT | 40 | 2-Stroke | 1995 | 679-W0078-A1-00 |
| Yamaha | C40ELRQ | 40 | 2-Stroke | 1992 | 679-W0078-A1-00 |
| Yamaha | C40PLRU | 40 | 2-Stroke | 1996 | 679-W0078-A1-00 |
| Yamaha | C40ELRS | 40 | 2-Stroke | 1994 | 679-W0078-A1-00 |
| Yamaha | C40PLRQ | 40 | 2-Stroke | 1992 | 679-W0078-A1-00 |
| Yamaha | C40MSHV | 40 | 2-Stroke | 1997 | 679-W0078-A1-00 |
| Yamaha | C40MLHS | 40 | 2-Stroke | 1994 | 679-W0078-A1-00 |
| Yamaha | C40PLRR | 40 | 2-Stroke | 1993 | 679-W0078-A1-00 |
| Yamaha | C40PLRS | 40 | 2-Stroke | 1994 | 679-W0078-A1-00 |
| Yamaha | C40ELRT | 40 | 2-Stroke | 1995 | 679-W0078-A1-00 |
| Yamaha | C40MLHT | 40 | 2-Stroke | 1995 | 679-W0078-A1-00 |
| Yamaha | C40MSHR | 40 | 2-Stroke | 1993 | 679-W0078-A1-00 |
| Yamaha | C40MSHS | 40 | 2-Stroke | 1994 | 679-W0078-A1-00 |
| Yamaha | C40PLRV | 40 | 2-Stroke | 1997 | 679-W0078-A1-00 |
| Yamaha | C40MSHQ | 40 | 2-Stroke | 1992 | 679-W0078-A1-00 |
| Yamaha | C40ELRR | 40 | 2-Stroke | 1993 | 679-W0078-A1-00 |
| Yamaha | C40ELRV | 40 | 2-Stroke | 1997 | 679-W0078-A1-00 |
| Yamaha | C40ESHV | 40 | 2-Stroke | 1997 | 679-W0078-A1-00 |
Technical Specs
- Product Type
- Outboard Water Pump Impeller Kit
- Installation
- Direct OEM Replacement
- Housing Material
- Marine-grade alloy (specification matches OEM)
What’s in the Box
- 1 × Water Seal Damper 2 (663-44366-00-00/663-44366-01-00)
- 1 × Insert Cup (676-44322-00-00)
- 1 × Impeller (6F5-44352-00-00)
- 1 × Water Pump Outer Gasket (676-44315-A0-00/676-44315-A1-00)
- 1 × Wear Plate/Cartridge Outer Plate (676-44323-00-00)
- 1 × Water Pump Gasket/Cartridge Gasket (676-44324-A0-00/676-44324-A1-00)
- 1 × Water Pump Gasket (679-44316-A0-00)
- 2 × Bolts (97095-08055-00)
- 2 × Bolts (97095-08045-00)
- 4 × Washers (92990-08600-00)
- 1 × Woodruff Key/Impeller Key (90280-04M00-00)
Installation Notes
- Disconnect the spark plug leads and battery for safety.
- Unbolt and carefully slide the lower unit (gearcase) off the outboard's driveshaft housing.
- Locate and unbolt the water pump housing cover. Take note of bolt positions.
- Remove the old impeller, gaskets, wear plate, and insert cup. Clean any debris or corrosion from the housing and mating surfaces.
- Install the new gaskets, wear plate, and insert cup from the kit.
- Slide the new woodruff key onto the driveshaft and install the new impeller, turning the driveshaft clockwise to seat the vanes correctly.
- Lightly grease the inside of the housing and the impeller with marine lubricant.
- Reinstall the water pump housing and tighten the bolts to the manufacturer's specified torque.
- Reattach the lower unit, ensuring the driveshaft, shift shaft, and water tube are correctly aligned.
- Reconnect the battery and spark plug leads. Start the engine and verify a strong, consistent water stream from the telltale outlet.
Troubleshooting & FAQ
What are the signs of a failing water pump impeller?
Common signs include the engine overheating at idle or low speeds, a weak or intermittent water stream from the "telltale" outlet, or an impeller that is visibly cracked, brittle, or has missing vanes upon inspection.
How often should I replace the water pump impeller?
For preventative maintenance, we recommend replacing the impeller every 1–2 years or every 100–200 hours of use, whichever comes first. Replacement is especially important for boats operated frequently in saltwater or silty conditions.
Will this kit fit a C40 model made after 1997?
No, this particular kit is specified to fit Yamaha C40 models only from 1991 through 1997. It is not confirmed for models made in other years. Always verify your engine's model and year before ordering.
What is the difference between OEM parts 6F5-W0078-A0-00 and 679-W0078-A1-00?
Part number 6F5-W0078-A0-00 was specified for the 1990 CV40 model, while 679-W0078-A1-00 was used for C40 models from 1991–1997. This aftermarket kit is engineered to serve as a direct, comprehensive replacement for both OEM part numbers.
Does this kit include the water pump housing?
No, this is an impeller rebuild kit. It contains the essential service components like the impeller, wear plate, insert cup, gaskets, and hardware, but it does not include the upper or lower water pump housing assembly.
Why do some gaskets list two part numbers?
The different part number suffixes (e.g., A0 vs. A1) typically reflect minor revisions or a change in supplier by the original manufacturer over the years. The components in our kit are designed to be fully compatible across all specified model years.
Is this an OEM part or an aftermarket replacement?
This listing is for a high-quality aftermarket replacement part, not an OEM component. It is built to meet or exceed OEM-level specifications using comparable materials and manufactured in an ISO 9002 certified facility, with batch inspections for quality assurance.
How fast is shipping and what does it cost?
We ship worldwide quickly, with typical transit times of 5–15 days for most regions. Standard shipping is free on all orders. Expedited shipping options, if available for your location, will be presented at checkout.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter any issues, 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 installation. If anything differs—even if your model appears compatible—do not purchase or install the part.
- This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
- Professional installation is highly recommended for safety, proper function, and to prevent engine damage.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to strict OEM-level tolerances and rigorously tested for real-world performance and durability.
- Fast Global Fulfillment — We offer free standard delivery to most regions worldwide, with typical transit times of just 5–15 days.
- Manufacturer-Direct Value — By working directly with our manufacturing partners, we provide fair, transparent pricing without compromising on materials or quality control.
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