Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-8508910)
Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-8508910) is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-85...
Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-8508910) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-8508910) is designed for a broad range of outboard engines, including Mercury/Mariner 15-50 HP 2-Stroke and 25-50 HP 4-Stroke models from 1977–2023, as well as select Force 25-50 HP outboards from 1995–1999. It serves as a crucial component for maintaining engine cooling system performance.
It provides a direct interchange for numerous part numbers, including Mercury 47-8508910, 47-8M0204712, Sierra 18-3057, and Mallory 9-45303, ensuring a precise fit for listed models.
- Engineered for direct-replacement installation.
- Constructed from durable neoprene/rubber compound for longevity in marine environments.
- Features a key slot design for secure and proper alignment during installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number |
|---|---|
| Mercury | 47-8508910 |
| Mercury | 47-850893 |
| Mercury | 47-850891 |
| Mercury | 47-8508920 |
| Mercury | 47-8M0024502 |
| Mercury | 47-8M0027792 |
| Mercury | 47-8M0204712 |
| Sierra | 18-3057 |
| Mallory | 9-45303 |
| GLM | 89640 |
| CEF | CEF500315 |
Engine & Model Compatibility
Confirm your engine model and year in the tables below.
This impeller fits a wide range of Mercury and Mariner outboards, from 2-stroke XD models to modern 4-strokes. Check your specific model and year for an exact match.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | XD Bigfoot | 15 | 2-Stroke | 1998–2006 | 47-8508910 | |
| Mercury | XD | 18/20 | 2-Stroke | 1984–2006 | 47-8508910 | |
| Mercury | SeaPro, Mara, Super15 | 25 | 2-Stroke | 1980–2006 | 47-8508910 | |
| Mercury | 2-cylinder | 30 | 2-Stroke | 1994–1998 | 47-8508910 | |
| Mercury | 30JET | 30 | 2-Stroke | 1998 | 47-8508910 | |
| Mercury | 2-cylinder | 40 | 2-Stroke | 1994–1998 | 47-8508910 | |
| Mercury | 3-cylinder | 25/30 | 4-Stroke | 1997–2023 | 47-8508910 | |
| Mercury | Standard | 40/50 | 4-Stroke | 1997–1999 | 47-8508910 | |
| Mercury | 3-cylinder | 40 | 4-Stroke | 1997–1998 | 47-8508910 | |
| Mercury | 3-cylinder | 50 | 4-Stroke | 1998 | 47-8508910 | |
| Mercury | 4-cylinder | 45/50 | 4-Stroke | 1999 | 47-8508910 | |
| Mercury | 75 | 2-Stroke | 1999 | 47-8508910 |
Also compatible with select Force outboards manufactured between 1995 and 1999.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Force | 25 | 2-Stroke | 1996–1998 | 0755466 | ||
| Force | 40 | 2-Stroke | 1995–1999 | 0755466 | ||
| Force | 50 | 2-Stroke | 1995–1999 | 0755466 |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct replacement
- Housing Material
- Neoprene/Rubber
- Housing Color
- Black
- Inner Diameter
- 16.0 mm
- Outer Diameter
- 73.0 mm
- Height
- 12.6 mm
- Other Technical Attributes
- Key slot design for secure installation
What’s in the Box
- 1 x Water Pump Impeller (Replaces 47-8508910)
- 1 x Key (Replaces 28-8M0032828)
- 1 x Gasket (Replaces 27-822189)
- 2 x Washers (Replaces 12-866451)
Installation Notes
- Disconnect the battery and remove the engine cover.
- Drain the lower unit gear lubricant.
- Remove the bolts securing the lower unit (gearcase) to the upper driveshaft housing.
- Carefully lower and separate the gearcase from the engine.
- Unbolt and remove the water pump housing to expose the old impeller.
- Note the orientation of the old impeller vanes, then remove the impeller and the old key.
- Clean the housing interior and inspect the wear plate and cup for scoring or damage. Replace if necessary.
- Install the new key, align the new impeller, and slide it into place, twisting in the direction of engine rotation to bend the vanes correctly.
- Reinstall the water pump housing, gaskets, and seals, ensuring bolts are torqued to manufacturer specifications.
- Reattach the lower unit to the engine, making sure the driveshaft, shift shaft, and water tube align correctly.
- Refill the gearcase with fresh lubricant and test the engine in water, confirming a steady stream from the tell-tale outlet.
Troubleshooting & FAQ
How do I know if this impeller fits my engine?
The most reliable method is to cross-reference your engine's original part number with the list in our Part Number Matrix. Additionally, consult the Engine & Model Compatibility table to confirm your specific model, horsepower, and year range are listed.
What are the signs of a failing water pump impeller?
Common signs include a weak or non-existent water stream from the "tell-tale" outlet, engine overheating alarms, and in severe cases, steam from the exhaust. Reduced engine performance at high RPMs can also indicate a cooling problem.
How often should I replace the water pump impeller?
As a preventative maintenance item, it is recommended to replace the impeller every 1-2 years or every 100-200 hours of operation, whichever comes first. Usage in saltwater or sandy/silty conditions may require more frequent replacement.
Is this a complete kit or just the impeller?
This package includes the impeller plus essential installation hardware: one key, one gasket, and two washers. Please see the "What's in the Box" section for a complete list of included components.
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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