Water Pump Impeller – Fits Mercury Marine 9.9-50 HP Outboards (Replaces 47-8508910, 47-850893, 47-8M0027792)
Water Pump Impeller – Fits Mercury Marine 9.9-50 HP Outboards (Replaces 47-8508910, 47-850893, 47-8M0027792) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
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 Marine 9.9-50 HP Outboards (Repl...
Product Details
This aftermarket Water Pump Impeller fits Mercury Marine 9.9-50 HP Outboards and is designed for reliable performance in a range of engines. It is a direct fit for Mercury Marine 9.9–25 HP 4-Stroke models (1984–2005) and 25–50 HP 2-Stroke models (1996–1999). It also fits select Force/Chrysler 25 HP (1996–1998), 40–50 HP (1995–1999), and 75 HP (1999) outboards.
Engineered to serve as a direct replacement, this impeller interchanges with Mercury part numbers 47-85089-1, 47-85089-10, 47-8M0027792, and others, along with Sierra 18-3057 and Mallory 9-45303 equivalents.
- Installation: Direct OEM replacement that fits the original factory pump housing.
- Material: Made from durable, corrosion-resistant neoprene rubber with a solid metal alloy hub.
- Essentials: Requires an impeller key for installation, which is typically included in most water pump service kits.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury | 47-85089-1 | Superseded |
| Mercury | 47-85089-3 | Superseded |
| Mercury | 47-85089-10 | Superseded |
| Mercury | 47-85089-20 | Superseded |
| Mercury | 47-8508910 | |
| Mercury | 47-850893 | |
| Mercury | 47-8M0024502 | Superseded |
| Mercury | 47-8M0027792 | Superseded |
| Mercury | 47-8M0204712 | Current |
| Sierra | 18-3057 | Aftermarket Interchange |
| Mallory | 9-45303 | Aftermarket Interchange |
| CEF | 500315 | Aftermarket Interchange |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury Marine outboards: Fits a variety of 2-stroke and 4-stroke models from 9.9 HP to 50 HP. Please verify your specific model and year range.
For Force/Chrysler outboards: Fitment is specific to certain serial number ranges. Please check your engine's serial number before ordering.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury Marine | 4-Stroke | 13.5 | 4-Stroke | 1984–2005 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 4-Stroke | 15 | 4-Stroke | 1984–2005 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 4-Stroke | 18 | 4-Stroke | 1984–2005 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 4-Stroke | 25 | 4-Stroke | 1984–2005 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 2-Cylinder | 20 | 2-Stroke | 1996–1999 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 2-Cylinder | 25 | 2-Stroke | 1996–1999 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 2-Cylinder | 30 | 2-Stroke | 1996–1999 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 2-Cylinder | 40 | 2-Stroke | 1996–1999 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 3-Cylinder | 40 | 2-Stroke | 1996–1999 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 3-Cylinder | 50 | 2-Stroke | 1996–1999 | 47-8508910, 47-8M0204712 | |
| Mercury Marine | 4-Stroke (323cc) | 9.9 | 4-Stroke | 1996–2005 | 47-8508910, 47-8M0204712 | |
| Force/Chrysler | Force | 25 | 2-Stroke | 1996–1998 | 47-8508910 | Serial# E127700-E344999 |
| Force/Chrysler | Force | 40 | 2-Stroke | 1995–1999 | 47-8508910 | Serial# E093700-E369299 |
| Force/Chrysler | Force | 50 | 2-Stroke | 1995–1999 | 47-8508910 | Serial# E093700-E369299 |
| Force/Chrysler | Force | 75 | 2-Stroke | 1999 | 47-8508910 | Serial# E345000-UP |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct OEM replacement
- Material
- Neoprene rubber with metal alloy hub
- Number of Blades
- 6
- Dimensions
- 7.13 in L × 6.0 in W × 0.5 in H
- Hub Shaft Diameter
- 16.0 mm (0.63 in)
- Weight
- 40 g (1.41 oz)
- Warranty
- Varies by manufacturer (typically 1 year)
- Other Technical Attributes
- Requires impeller key (included in most service kits)
What’s in the Box
Package contents depend on the option selected:
-
Impeller Only (OEM Replacement):
- 1 x Water Pump Impeller
-
Full Service Kit (if selected):
- 1 x Water Pump Impeller
- 2 x Seal
- 1-2 x Gasket (varies by kit)
- 1 x O-Ring (in some kits)
- 1 x Impeller Key (28-85119)
Installation Notes
- Disconnect the negative battery cable for safety.
- Remove the lower unit (gearcase) from the outboard by unbolting it. You may need to disconnect the shift linkage.
- Place the lower unit on a workbench and unbolt the water pump housing cover.
- Note the rotational direction of the old impeller blades before removing it.
- Slide the old impeller off the driveshaft. Remove the impeller key and old gaskets.
- Thoroughly clean the impeller housing, wear plate, and all mating surfaces.
- Install the new impeller key into the driveshaft keyway.
- Apply a thin coat of marine grease or a soap/water solution to the inside of the pump housing and the new impeller.
- Slide the new impeller onto the driveshaft, aligning it with the key. Rotate the driveshaft clockwise while pushing the housing down to correctly fold the blades.
- Reinstall the water pump housing with new gaskets and seals, ensuring bolts are tightened to the manufacturer's torque specifications.
- Reattach the lower unit to the outboard, reconnecting the shift linkage.
- Once fully assembled, test the engine in water, confirming a steady stream of water from the tell-tale port.
Troubleshooting & FAQ
How do I know if my water pump impeller is failing?
Common signs include the engine overheating at idle or low speeds, a weak or intermittent water stream from the "tell-tale" outlet, or a visibly dry-rotted, cracked, or stiff impeller during inspection.
How often should I replace my impeller?
For optimal reliability, it's recommended to replace the impeller every 1-2 years or every 100-200 operating hours. Replacement frequency should be increased if you operate in sandy, silty, or saltwater conditions.
Is the impeller key included with this part?
This listing is for the individual impeller only. The impeller key is not included unless you purchase a complete water pump service kit, which typically bundles the key with gaskets and seals.
What is the correct orientation for the impeller blades during installation?
The blades are flexible. While sliding the pump housing over the impeller, turn the driveshaft in its normal direction of rotation (usually clockwise). This will cause the blades to bend correctly into place without damage.
What's the difference between an OEM and an aftermarket impeller?
This listing is an aftermarket replacement (not OEM). It is built to meet or exceed OEM-level specifications using comparable high-quality materials. Our parts are manufactured in an ISO 9002 certified facility and are batch-inspected for quality and consistency.
What are the shipping speed and cost?
We ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free to most regions, with expedited options available at checkout where applicable.
What is the warranty and return policy?
This part 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 parts 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 purchase. If anything differs—even if your model appears on the compatibility list—do not order.
- This is an aftermarket replacement component, not an original equipment manufacturer (OEM) part.
- Professional installation is highly recommended to ensure safety, proper function, and engine longevity.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world reliability and performance.
- Fast Global Fulfillment — We offer free standard delivery to most regions with an average transit time of 5–15 days, getting you back on the water faster.
- Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without ever compromising on materials or quality control.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
