Water Pump Impeller Repair Kit – Fits Yamaha, Mercury Mariner 6-8 HP Outboards (Replaces 6G1-W0078-A1-00, 6N0-W0078-A0-00)
Water Pump Impeller Repair Kit – Fits Yamaha, Mercury Mariner 6-8 HP Outboards (Replaces 6G1-W0078-A1-00, 6N0-W0078-A0-00) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Water Pump Impeller Repair Kit – Fits Yamaha, Mercury Mariner 6-8 H...
Product Details
This Water Pump Impeller Repair Kit – Fits Yamaha, Mercury Mariner 6-8 HP Outboards provides a comprehensive solution for servicing your engine's cooling system. It is designed for Yamaha 6-8 HP 2-stroke outboards (1984–2000) and Mercury Mariner 6-8 HP 2-stroke outboards (1984–1986), including models 6C, 6D, and 8C.
This kit serves as a direct interchange for Yamaha part numbers 6G1-W0078-A1-00, 6G1-W0078-00-00, 6G1-W0078-01-00, Mercury Mariner 6N0-W0078-A0-00, 6N0-W0078-0A-00, and Sierra 18-3460.
- Engineered as a direct OEM-level replacement for straightforward installation.
- Constructed from marine-grade metal alloys and chemical-resistant neoprene rubber.
- Includes all necessary gaskets, plates, and hardware for a complete overhaul.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 6G1-W0078-A1-00 |
| Yamaha | 6G1-W0078-00-00 |
| Yamaha | 6G1-W0078-01-00 |
| Mercury Mariner | 6N0-W0078-A0-00 |
| Mercury Mariner | 6N0-W0078-0A-00 |
| Sierra | 18-3460 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit fits a wide range of Yamaha 6 HP and 8 HP 2-stroke outboards manufactured between 1984 and 2006+, including international models.
It is also compatible with specific Mercury Mariner 6C, 6D, and 8C 2-stroke models from 1984 to 1986.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 6 HP | 6 | 2-Stroke | 1984–1996 | 6G1-W0078-A1-00 | International models included |
| Yamaha | 8 HP | 8 | 2-Stroke | 1984–1985, 1988–1996 | 6G1-W0078-A1-00 | International models included |
| Yamaha | 8LN, 8SN | 8 | 2-Stroke | 1984 | 6G1-W0078-A1-00 | |
| Yamaha | 8LK, 8SK | 8 | 2-Stroke | 1985 | 6G1-W0078-A1-00 | |
| Yamaha | 6LG, 6SG | 6 | 2-Stroke | 1988 | 6G1-W0078-A1-00 | |
| Yamaha | 8LG, 8SG | 8 | 2-Stroke | 1988 | 6G1-W0078-A1-00 | |
| Yamaha | 6LF, 6SF | 6 | 2-Stroke | 1989 | 6G1-W0078-A1-00 | |
| Yamaha | 8LF, 8SF | 8 | 2-Stroke | 1989 | 6G1-W0078-A1-00 | |
| Yamaha | 6LD, 6SD | 6 | 2-Stroke | 1990 | 6G1-W0078-A1-00 | |
| Yamaha | 8LD, 8SD | 8 | 2-Stroke | 1990 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHP, 6MSHP | 6 | 2-Stroke | 1991 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHP, 8MSHP | 8 | 2-Stroke | 1991 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHQ, 6MSHQ | 6 | 2-Stroke | 1992 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHQ, 8MSHQ | 8 | 2-Stroke | 1992 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHR, 6MSHR | 6 | 2-Stroke | 1993 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHR, 8MSHR | 8 | 2-Stroke | 1993 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHS, 6MSHS | 6 | 2-Stroke | 1994 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHS, 8MSHS | 8 | 2-Stroke | 1994 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHT, 6MSHT | 6 | 2-Stroke | 1995 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHT, 8MSHT | 8 | 2-Stroke | 1995 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHU, 6MSHU | 6 | 2-Stroke | 1996 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHU, 8MSHU | 8 | 2-Stroke | 1996 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHV, 6MSHV | 6 | 2-Stroke | 1997 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHV, 8MSHV | 8 | 2-Stroke | 1997 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHW, 6MSHW | 6 | 2-Stroke | 1998 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHW, 8MSHW | 8 | 2-Stroke | 1998 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHX, 6MSHX | 6 | 2-Stroke | 1999 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHX, 8MSHX | 8 | 2-Stroke | 1999 | 6G1-W0078-A1-00 | |
| Yamaha | 6MLHY, 6MSHY | 6 | 2-Stroke | 2000 | 6G1-W0078-A1-00 | |
| Yamaha | 8MLHY, 8MSHY | 8 | 2-Stroke | 2000 | 6G1-W0078-A1-00 | |
| Yamaha | 8MSHZ | 8 | 2-Stroke | 2001 | 6G1-W0078-A1-00 | |
| Yamaha | 8MSHA | 8 | 2-Stroke | 2002 | 6G1-W0078-A1-00 | |
| Yamaha | 8MSHB | 8 | 2-Stroke | 2003 | 6G1-W0078-A1-00 | |
| Yamaha | 8MSHC | 8 | 2-Stroke | 2004 | 6G1-W0078-A1-00 | |
| Yamaha | 8MSHD | 8 | 2-Stroke | 2005 | 6G1-W0078-A1-00 | |
| Yamaha | 8MSH | 8 | 2-Stroke | 2006 and later | 6G1-W0078-A1-00 | End year unspecified |
| Mercury Mariner | 6C, 6D | 6 | 2-Stroke | 1984–1986 | 6N0-W0078-A0-00 | |
| Mercury Mariner | 8C | 8 | 2-Stroke | 1984–1986 | 6N0-W0078-A0-00 | |
| Mercury Mariner | 11656M, 11656T | 2-Stroke | Models mentioned in sources but HP/Years not specified |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit
- Installation
- Direct OEM replacement
- Fuel Type
- Gasoline
- Housing Material
- Metal alloy and neoprene rubber
- Housing Color
- As shown in images (metallic/black)
- Dimensions
- 6.0" H x 10.0" W x 12.0" L
- Weight
- 0.2 kg (0.44 lb)
- Warranty
- 30-day return policy (retailer dependent)
- Other Attributes
- Marine and chemical corrosion resistant
What’s in the Box
- 1 x Impeller (6G1-44352-00/18-3066)
- 1 x Wear Plate (6G1-44323-00)
- 1 x Insert Cup (6G1-44322-02)
- 1 x Water Pump Gasket (6G1-44315-A0)
- 1 x Plate Kit (6G1-44328-00)
- 1 x Damper, Water Seal (647-44366-00)
- 4 x Bolts/Washer (97080-06405-00)
Installation Notes
- Disconnect the battery and remove the engine cover.
- Drain the lower unit gear lube.
- Remove the bolts securing the lower unit to the engine's upper casing.
- Carefully lower and remove the lower unit assembly. Place it on a stable workbench.
- Locate the water pump housing and unbolt it to expose the impeller.
- Note the orientation of the old impeller fins before removing it.
- Remove the old impeller, gasket, wear plate, and insert cup. Clean all surfaces thoroughly.
- Install the new gasket, wear plate, and insert cup from the kit.
- Slide the new impeller into place, rotating the driveshaft in its normal direction of operation to bend the fins correctly.
- Reinstall the water pump housing, tightening bolts to the manufacturer's specified torque.
- Reattach the lower unit to the engine, ensuring all connections are secure.
- Refill the lower unit with fresh gear lube and test the engine in water to verify proper cooling system function.
Troubleshooting & FAQ
How can I confirm this fits my specific outboard model?
The most reliable way is to cross-reference your engine's model and year with the compatibility tables provided on this page. For example, if you have a Yamaha 8 HP from 1995, you will find a matching entry (8MLHT, 8MSHT) in the table. If you are still unsure, check the part number on your existing water pump housing or impeller.
What are the signs of a failing water pump impeller?
Common signs include the engine overheating, a weak or non-existent water stream from the "telltale" outlet, an alarm sounding (on equipped models), or visible cracks and hardening of the old impeller's rubber fins upon inspection.
How often should the water pump impeller be replaced?
As a general maintenance guideline, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of operation, whichever comes first. This interval can be shorter if you frequently operate in sandy, silty, or saltwater environments.
Is this kit difficult to install?
Installation requires basic mechanical skills and tools to drop the lower unit of your outboard. While many boat owners perform this maintenance themselves, we recommend professional installation if you are not comfortable with the process to ensure safety and correct function.
Does the direction of the impeller fins matter during installation?
Yes, it's critical. The impeller fins must be oriented to bend in the direction of the driveshaft's normal rotation. Installing them backwards will cause premature failure and no water flow. Always check the old impeller's orientation before removal or turn the driveshaft clockwise while pushing the new impeller down into the housing.
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.
Payment & Security
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