Water Pump Impeller Kit – Fits Yamaha 4-Stroke 70HP F70A (Replaces 6CJ-W0078-00, 6CJ-W0078-01, Sierra 18-3494)
Water Pump Impeller Kit – Fits Yamaha 4-Stroke 70HP F70A (Replaces 6CJ-W0078-00, 6CJ-W0078-01, Sierra 18-3494) 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 4-Stroke 70HP F70A (Replaces ...
Water Pump Impeller Kit – Fits Yamaha 4-Stroke 70HP F70A (Replaces 6CJ-W0078-00, 6CJ-W0078-01, Sierra 18-3494) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Water Pump Impeller Kit is designed for Yamaha 4-Stroke outboard motors, including F70, F70A, F70LA, and F40G models from 2010 to current. It provides all necessary components for a complete water pump service to restore cooling system performance and prevent engine overheating.
The kit serves as a direct cross-reference for Yamaha OEM part numbers 6CJ-W0078-00, 6CJ-W0078-01, and 6CJ-W0078-02, and it is an interchange for Sierra part 18-3494.
- Engineered as a direct OEM-equivalent replacement for a precise fit.
- Features a durable neoprene rubber impeller and stainless steel hardware for corrosion resistance.
- A complete kit including the impeller, housing, wear plate, gaskets, seals, and bolts.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha | 6CJ-W0078-02 | Current active part number. |
| Yamaha | 6CJ-W0078-01 | Supersedes 6CJ-W0078-00. |
| Yamaha | 6CJ-W0078-00 | Original part number. |
| Sierra | 18-3494 | Aftermarket interchange. |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is confirmed to fit the following Yamaha outboard models. Always verify your specific model and year range before ordering.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | F70 | 70 | 4-Stroke | 2010–Current | 6CJ-W0078-00 | Superseded by 6CJ-W0078-01, 6CJ-W0078-02 |
| Yamaha | F70A | 70 | 4-Stroke | 2010–Current | 6CJ-W0078-00 | Superseded by 6CJ-W0078-01, 6CJ-W0078-02 |
| Yamaha | F70LA | 70 | 4-Stroke | 2010–Current | 6CJ-W0078-00 | Models 0113, 0114, 0115, 0116, 0310, 0410, 0112, 0411 |
| Yamaha | F40G | 40 | 4-Stroke | 6CJ-W0078-00 | Mentioned in product description |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit
- Installation
- Direct OEM replacement
- Material
- Neoprene Rubber Impeller, Stainless Steel
- Weight
- 0.26 kg (0.57 lb)
- Other Attributes
- Complete kit with all required gaskets, seals, and hardware
What’s in the Box
- 1 x Neoprene Impeller (6H3-44352-00-00)
- 1 x Cup, Insert (63D-44322-00-00)
- 1 x Plate, Wear (6CJ-44323-00-00)
- 1 x Water Pump Gasket (6CJ-44315-00-00)
- 1 x Water Pump Gasket (6CJ-44316-00-00)
- 1 x Cartridge Gasket (6CJ-44324-00-00)
- 1 x Water Pump Housing Cover (63D-44312-00-00)
- 1 x Grommet (663-44366-00-00)
- 1 x O-Ring (93210-46044)
- 1 x Woodruff Key (90280-03M03-00)
- 2 x Oil Seal (93101-23070-00)
- 2 x Dowel Pin (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 shift the outboard into neutral.
- Remove the lower unit (gearcase) from the outboard midsection. This typically requires removing several bolts.
- Place the lower unit on a workbench and locate the water pump housing, usually found on top of the gearcase.
- Unbolt and remove the water pump housing cover to access the impeller.
- Remove the old impeller, wear plate, gaskets, and seals. Note the orientation of the impeller vanes.
- Clean all mating surfaces thoroughly, removing any old gasket material or corrosion.
- Install the new gaskets, seals, wear plate, and insert cup from the kit.
- Install the new impeller. Lightly lubricate the inside of the housing and turn the driveshaft clockwise while pushing down to seat the impeller. The vanes should bend in a clockwise direction.
- Reinstall the housing cover and tighten the bolts to the manufacturer's specified torque.
- Reinstall the lower unit onto the outboard, ensuring the water tube and shift shaft are properly aligned.
- Once assembled, start the engine in water and verify that a steady stream of water is exiting the "telltale" outlet.
Troubleshooting & FAQ
What are the signs of a failing water pump impeller?
Common symptoms include a weak or intermittent water stream from the engine's telltale outlet, engine overheating alarms, or a "hot engine" warning light. Upon inspection, a worn impeller may have cracked, brittle, or broken vanes.
How often should the water pump impeller be replaced?
As a general rule, inspect the impeller annually and replace it every 1 to 2 years or every 100 to 200 hours of operation, whichever comes first. Replacement intervals should be shorter if operating in sandy, silty, or saltwater environments.
Does this kit include the housing?
Yes, this is a comprehensive repair kit that includes the Water Pump Housing Cover (63D-44312-00-00), along with the impeller, insert cup, wear plate, gaskets, seals, and all hardware required for a full service.
Will this kit fit my Yamaha F40G outboard?
This kit is listed as compatible with certain Yamaha F40G models. However, because specific model years are not fully defined, we strongly recommend verifying that your engine's required part number matches one of the references in the Part Number Matrix before purchasing.
Do I need any special tools or sealants for installation?
Basic mechanic's tools are required. While no special tools are typically needed, a torque wrench is recommended for tightening bolts to factory specifications. A thin layer of marine grease on the new impeller can aid installation, but no other sealants are usually necessary.
Is this kit for saltwater or freshwater use?
The components, including the stainless steel hardware and neoprene impeller, are designed for reliable performance in both saltwater and freshwater environments.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and manufactured in an ISO 9002 facility, with batch inspections for consistency.
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 conditions. 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/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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