Water Pump Impeller – Fits Mercury/Mariner 3.5-6 HP Outboards (Replaces 47-22748, 18-3012)
Water Pump Impeller – Fits Mercury/Mariner 3.5-6 HP Outboards (Replaces 47-22748, 18-3012) 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 3.5-6 HP Outboards (Repl...
Product Details
This Water Pump Impeller – Fits Mercury/Mariner 3.5-6 HP Outboards (Replaces 47-22748, 18-3012) is an aftermarket replacement part for a range of Mercury 2-stroke outboards from the 1950s to the 1980s, including 3.5, 3.9, 5, and 6 HP models, as well as vintage "Mark" series motors. It ensures your engine’s cooling system functions correctly, preventing overheating.
It serves as a direct interchange for Mercury/Quicksilver 47-22748, Sierra 18-3012, Mallory 9-45308, and Johnson/Evinrude/OMC 508388/775465.
- Engineered as a direct OEM-style replacement for simple installation.
- Constructed from durable neoprene with a brass hub for reliable service.
- Includes a 1-year factory warranty against manufacturing defects.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/Quicksilver | 47-22748 |
| Sierra | 18-3012 |
| Mallory | 9-45308 |
| Johnson/Evinrude/OMC | 508388/775465 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This part primarily fits vintage Mercury and Mariner outboards. Please check your serial number range carefully.
Cross-references indicate this part may also fit certain Johnson/Evinrude models, but specific application data is not available. Verify by part number.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 3.5 HP | 3.5 | 2-Stroke | 358136-6202172 | 47-22748 | |
| Mercury | 3.9 HP | 3.9 | 2-Stroke | 1655013-2498135 | 47-22748 | |
| Mercury | 5 HP | 5 | 2-Stroke | 338136-574128 | 47-22748 | |
| Mercury | 6 HP | 6 | 2-Stroke | 888005-1916138 | 47-22748 | |
| Mercury | Mark 5, KF5, KF3 | 2-Stroke | All | 47-22748 | Vintage series | |
| Mercury | Mark 6, 6A | 2-Stroke | All | 47-22748 | Vintage series | |
| Mercury | 110 | 2-Stroke | 1470349-1865778 | 47-22748 |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct OEM replacement
- Fuel Type
- Gasoline
- Housing Material
- Neoprene with brass hub
- Product Dimensions
- Height: 4.0; Width: 5.13; Length: 0.5
- Weight
- 13 g (0.81 oz)
- Number of Blades
- 6
What’s in the Box
- 1 x Water Pump Impeller (Replaces 47-22748)
Installation Notes
- Disconnect the spark plug wire(s) for safety.
- Unbolt and remove the lower unit (gearcase) from the outboard.
- Locate and unbolt the water pump housing.
- Remove the old impeller, noting the direction of the vanes.
- Clean the inside of the pump housing and inspect it for wear or damage.
- Apply a lubricant (silicone grease, glycerine, or dish soap) to the inside of the housing and to the new impeller.
- Install the new impeller, rotating the driveshaft in the normal direction of rotation to bend the vanes correctly.
- Reassemble the water pump housing, ensuring a proper seal.
- Reinstall the lower unit and test the engine in water, confirming a steady stream from the tell-tale outlet.
Troubleshooting & FAQ
Which engines does this impeller fit?
This impeller is designed for a range of vintage Mercury and Mariner 2-stroke outboards, including 3.5, 3.9, 5, and 6 HP models, as well as Mark 5, Mark 6, and 110 series engines. Always confirm fitment using the serial number ranges provided in the compatibility list.
How do I know if my water pump impeller is failing?
Common signs of a worn or failed impeller include a weak or non-existent stream of water from the "tell-tale" outlet, an engine temperature alarm, or the engine overheating. Reduced engine performance can also be a symptom.
How often should I replace my impeller?
For preventative maintenance, it is recommended to inspect your impeller annually and replace it every 1-2 years, depending on usage (hours) and water conditions (saltwater, sandy, or silty water may require more frequent changes).
What lubricant should I use for installation?
Lubricate the impeller and pump housing with silicone grease, glycerine, or a small amount of dish soap. This prevents damage to the impeller during the initial dry start-up.
Is this an OEM part?
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.
What are the shipping speed and cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
What is the warranty and return policy?
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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