Water Pump Impeller – Fits Mercury Marine 3.9, 6 & 9.8 HP (Replaces Mercury Marine 47-22748, Sierra Marine 18-3074)
Water Pump Impeller – Fits Mercury Marine 3.9, 6 & 9.8 HP (Replaces Mercury Marine 47-22748, Sierra Marine 18-3074) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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Water Pump Impeller – Fits Mercury Marine 3.9, 6 & 9.8 HP (Repl...
Water Pump Impeller – Fits Mercury Marine 3.9, 6 & 9.8 HP (Replaces Mercury Marine 47-22748, Sierra Marine 18-3074) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller – Fits Mercury Marine 3.9, 6 & 9.8 HP (Replaces 47-22748) is a direct-fit replacement for maintaining the cooling system on Mercury Marine 2-Stroke 3.9 HP, 6 HP (1974–2007) and 4-Stroke 9.8 HP engines. Engineered for reliability, it ensures your engine receives proper water circulation to prevent overheating.
It serves as a direct cross-reference for multiple part numbers, including Mercury Marine 47-22748, Sierra Marine 18-3074, and Mallory 9-45308.
- Installation Method: Direct Replacement
- Environment: Fully compatible with saltwater and freshwater
- Included Components: Impeller with brass hub
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury Marine | 47-22748 |
| Sierra Marine | 18-3074 |
| Mallory | 9-45308 |
| AM | AM47-22748 |
| GLM | 89600 |
| SEI Marine | 96-299-03C |
| CEF | 500309 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury engines, please verify your model and serial number range (S/N) below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 3.9 | 3.9 HP | 2-Stroke | S/N 1655013–2498135 | 47-22748 | |
| Mercury | 6 | 6 HP | 2-Stroke | S/N 888005–1916138 | 47-22748 | |
| Mercury | 9.8 | 9.8 HP | 4-Stroke | model 110 (2 CYL) | 47-22748 | |
| Mercury | Mark 5 | 5 HP | 2-Stroke | S/N 574128–786612 | 47-22748 | |
| Mercury | Mark 6, 6A | 6 HP | 2-Stroke | S/N 888005–UP | 47-22748 | |
| Mercury | 3.5 HP | 3.5 HP | 2-Stroke | S/N 358136–6202172 | 47-22748 |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct Replacement
- Housing Material
- Neoprene with Brass Hub
- Housing Color
- Black
- Blade Dimensions
- A: 11.60mm (0.456"), B: 32.00mm (1.26"), C: 14.40mm (0.567")
- Number of Blades
- 6
- Weight
- 90g (0.45 oz)
- Fitting Type
- Direct Fit
- Saltwater Rating
- Compatible
What’s in the Box
- 1 x Water Pump Impeller (47-22748)
Installation Notes
- Disconnect the battery to prevent accidental starting.
- Place a container under the lower unit and drain the gearcase lube.
- Remove the lower unit (outdrive) from the engine assembly.
- Unbolt and remove the water pump housing to access the old impeller.
- Inspect the housing, wear plate, and seals for scoring, warping, or damage. Replace if necessary.
- Slide the new impeller onto the driveshaft, ensuring the blades are oriented correctly (typically in the direction of shaft rotation).
- Reassemble the water pump housing, applying a light coat of marine grease.
- Reinstall the lower unit, ensuring the driveshaft and water tube are properly aligned.
- Refill the gearcase with the manufacturer-specified lubricant.
- Once reassembled, start the engine in water and verify a strong, steady stream from the "telltale" water outlet.
Troubleshooting & FAQ
How do I know if this impeller fits my Mercury engine?
Refer to the compatibility table and verify your engine model, horsepower, and, most importantly, its serial number (S/N). If your engine's S/N falls within the specified range for your model, this part should fit.
What are the signs of a failing water pump impeller?
Common symptoms include the engine overheating, especially at idle or low speeds; a weak or non-existent water stream from the "telltale" outlet; and a brittle or cracked appearance on the old impeller's blades upon inspection.
How often should I replace my outboard's impeller?
For preventative maintenance, it is recommended to replace the impeller every 1 to 2 years, or every 100-200 hours of operation. More frequent replacement may be necessary if operating primarily in saltwater or sandy/silty conditions.
Is this impeller safe for saltwater use?
Yes. This impeller is manufactured with a durable neoprene housing and a corrosion-resistant brass hub, making it fully suitable for saltwater environments.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It has been built to OEM-level specifications with comparable materials. Our parts are manufactured in an ISO 9002 facility and are batch-inspected for consistency and quality.
Shipping speed & cost?
We ship worldwide quickly—typical transit is 5–15 days for most regions. Standard shipping is free; expedited options will appear at checkout where available for your location.
Warranty & returns?
This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window, provided the item is unused and in its original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before purchasing. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement component, not an original OEM part.
- Professional installation is highly recommended for safety and optimal performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions with a typical transit time of 5–15 days.
- Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.
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