Water Pump Impeller – Fits Mercury/Mariner 25-50HP (Replaces 47-8M0024502, 47-850893)
Water Pump Impeller – Fits Mercury/Mariner 25-50HP (Replaces 47-8M0024502, 47-850893) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Water Pump Impeller – Fits Mercury/Mariner 25-50HP (Replaces 47-8M0...
Product Details
This high-performance Water Pump Impeller is designed for a wide range of Mercury/Mariner outboards from 25HP to 50HP (2 & 4-Stroke, 1984–up) and Force/Chrysler outboards from 25HP to 75HP (2-Stroke, 1995–1999) with compatible water pump assemblies.
It serves as a direct aftermarket replacement for multiple OEM part numbers, including Mercury Marine 47-8M0024502 and Sierra 18-3057, ensuring a precise fit and reliable cooling performance.
- Designed for direct OEM replacement for straightforward installation.
- Crafted from durable, high-strength neoprene rubber for longevity.
- Features a 6-blade configuration for efficient water flow.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury Marine | 47-850893 |
| Mercury Marine | 47-85089 |
| Mercury Marine | 47-8508910 |
| Mercury Marine | 47-8508920 |
| Mercury Marine | 47-8M0024502 |
| Mercury Marine | 47-8M0027792 |
| Mercury Marine | 8M0204712 |
| Sierra | 18-3057 |
| GLM | 89640 |
| Mallory | 9-45303 |
| Mallory | 9-45303-10 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/Mariner Outboards: Please verify your engine's serial number (S/N) to ensure correct fitment according to the specified ranges.
For Force/Chrysler Outboards: Compatibility is based on the model year and serial number range provided.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | 18HP | 18 | 2-Stroke | 1984–up (S/N 5837437-up) | 47-850893 | |
| Mercury/Mariner | 20HP | 20 | 2-Stroke | 1984–up (S/N 6443973-up) | 47-850893 | |
| Mercury/Mariner | 25, 25XD, 25 Sea Pro | 25 | 2-Stroke | 1984–up (S/N 5705532-up) | 47-850893 | |
| Mercury/Mariner | 25 (3cyl.) | 25 | 2-Stroke | 1984–up (S/N E268781-up) | 47-850893 | |
| Mercury/Mariner | 30 Jet | 30 | 2-Stroke | 1984–up (S/N G590000-up) | 47-850893 | |
| Mercury/Mariner | 30 (2cyl) | 30 | 2-Stroke | 1984–up (S/N G053314-up) | 47-850893 | |
| Mercury/Mariner | 40 (2 cyl) | 40 | 2-Stroke | 1984–up (S/N G053314-up) | 47-850893 | |
| Mercury/Mariner | 40 (3cyl) | 40 | 2-Stroke | 1984–up (S/N G531301-up) | 47-850893 | |
| Mercury/Mariner | 40 (4-stroke, std) | 40 | 4-Stroke | (S/N G231123–G760299) | 47-850893 | |
| Mercury/Mariner | 40 (4-stroke, 2:1 ratio) | 40 | 4-Stroke | (S/N G760300–T408999) | 47-850893 | |
| Mercury/Mariner | 45 (4-stroke, Bodensee) | 45 | 4-Stroke | (S/N G231123-up) | 47-850893 | |
| Mercury/Mariner | 50 (3cyl) | 50 | 2-Stroke | 1984–up (S/N G590000-up) | 47-850893 | |
| Mercury/Mariner | 50 (4-stroke, std) | 50 | 4-Stroke | (S/N G231123-up) | 47-850893 | |
| Mercury/Mariner | BigFoot | 8–15 | 4-Stroke | 47-850893 | Models with BigFoot gear case | |
| Force/Chrysler | 25HP | 25 | 2-Stroke | 1996–1998 (S/N E127700–E344999) | 47-850893 | |
| Force/Chrysler | 40/50HP | 40/50 | 2-Stroke | 1995–1999 (S/N E093700–E369299) | 47-850893 | |
| Force/Chrysler | 75HP | 75 | 2-Stroke | 1999 (S/N E345000-up) | 47-850893 |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct OEM replacement
- Connection
- Internal hub mount
- Housing Material
- Neoprene rubber
- Housing Color
- Black
- Dimensions
- Diameter: 73.00mm (2.906"), Height: 12.60mm (0.496"), Internal Hub: 16.00mm (0.629")
- Weight
- 41g (0.09 lbs)
- Fitting Type
- 6-blade impeller
- Other Technical Attributes
- 6 blade configuration
What’s in the Box
- 1 x Water Pump Impeller (47-850893/47-8M0024502)
Installation Notes
- Before starting, disconnect the engine's battery and remove the negative terminal.
- Place the outboard motor in a secure, upright position and remove the lower unit (gearcase) by unbolting it from the engine leg.
- Locate and remove the bolts securing the water pump housing cover.
- Carefully lift the housing, noting the orientation of the old impeller's blades for reference.
- Remove the old impeller, woodruff key, and any gaskets or wear plates.
- Thoroughly clean the inside of the pump housing and all mating surfaces.
- Install the new wear plate and gaskets as required by your model.
- Slide the woodruff key into its slot on the driveshaft and apply a light coat of marine grease to the new impeller's interior.
- Install the new impeller by pushing down while turning the driveshaft clockwise to correctly bend the blades.
- Reinstall the water pump housing, tighten bolts to the manufacturer's torque specification, and reattach the lower unit.
- Reconnect the battery, supply cooling water to the engine, and briefly run it to confirm proper water circulation from the tell-tale outlet.
Troubleshooting & FAQ
How do I know if this impeller fits my specific engine model?
This impeller fits a wide range of Mercury, Mariner, and Force/Chrysler models. The best way to confirm fitment is to check your engine's model, horsepower, and serial number against the compatibility tables on this page. If your part number matches one listed in the Part Number Matrix, it is also compatible.
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. A cracked, brittle, or worn-down impeller cannot pump water effectively to cool the engine.
How often should the water pump impeller be replaced?
As a general maintenance item, 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 or silty water.
My engine is overheating, but the tell-tale stream looks fine. Could the impeller still be the cause?
Yes. While a weak tell-tale stream is a key indicator, a worn impeller might still produce a visible stream at idle but fail to provide sufficient water volume and pressure at higher RPMs, leading to overheating under load. Other causes could include a thermostat issue or blockages in the cooling passages.
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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