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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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 – Fits Mercury/Mariner 15-50 HP (Replaces 47-85...
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.
Payment & Security
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