Water Pump Impeller Kit – Fits Mercury 4–9.8 HP (Replaces 46-70941A3)
Water Pump Impeller Kit – Fits Mercury 4–9.8 HP (Replaces 46-70941A3) 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
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Water Pump Impeller Kit – Fits Mercury 4–9.8 HP (Replaces 46-70941A3)
Water Pump Impeller Kit – Fits Mercury 4–9.8 HP (Replaces 46-70941A3) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit – Fits Mercury 4–9.8 HP (Replaces 46-70941A3) is designed for Mercury Marine 2-stroke outboard motors, including 4 HP, 4.5 HP, 7.5 HP, and 9.8 HP models manufactured between 1975 and 1986. It restores cooling system performance to prevent overheating and ensure engine reliability.
It serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 46-70941A3, Sierra 18-3446, GLM 12122, and Sierra 18-3447, offering a versatile cross-reference solution.
- Engineered for direct-fit installation.
- Restores cooling system integrity and water pressure.
- Includes all essential components for a standard service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 46-70941A3 |
| Sierra | 18-3446 |
| GLM | 12122 |
| Sierra | 18-3447 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | Outboard | 4 | 2-Stroke | 1975–1986 | 46-70941A3 | |
| Mercury | Outboard | 4.5 | 2-Stroke | 1975–1986 | 46-70941A3 | |
| Mercury | Outboard | 7.5 | 2-Stroke | 1975–1986 | 46-70941A3 | |
| Mercury | Outboard | 9.8 (Model 110) | 2-Stroke | 1975–1986 | 46-70941A3 |
Technical Specs
- Product Type
- Water Pump Impeller Kit
- Installation
- Direct replacement
What’s in the Box
- Impeller
- Gaskets/O-rings
- Additional components typically found in water pump service kits
Installation Notes
- Disconnect the battery and spark plug wires for safety.
- Place a drain pan under the lower unit and remove the drain/fill screws to empty the gear oil.
- Remove the bolts securing the lower unit (gearcase) to the engine's midsection.
- Carefully lower the gearcase to access the water pump housing.
- Unbolt and remove the water pump housing to expose the old impeller.
- Note the orientation of the old impeller vanes before removing it.
- Clean the housing interior and replace gaskets, seals, and the wear plate.
- Install the new impeller, turning the driveshaft clockwise to bend the vanes correctly.
- Reinstall the housing, ensuring a proper seal.
- Reattach the lower unit, refill with fresh gear oil, and reconnect the battery/plugs.
- Test the engine in water, confirming a steady stream from the tell-tale port.
Troubleshooting & FAQ
How do I confirm this kit fits my specific engine?
Check your engine's model, horsepower, and year. Compare it against the "Engine & Model Compatibility" table. You can also verify by cross-referencing your existing part number with those in the "Part Number Matrix".
What are the signs of a failing water pump impeller?
Common symptoms include a weak or non-existent water stream from the "tell-tale" outlet, engine overheating alarms, and reduced engine performance. Visible damage to the old impeller, like cracked, brittle, or missing vanes, also indicates it needs replacement.
How often should I replace my impeller?
As a general maintenance rule, it is recommended to inspect and/or replace the water pump impeller every 1–2 years or every 100–200 hours of operation, depending on usage conditions (e.g., more frequently in saltwater or sandy/silty environments).
What is the difference between this kit and an OEM one?
Our aftermarket kits are engineered to meet or exceed original equipment manufacturer (OEM) specifications for fit, form, and function. They are made with comparable materials in an ISO 9002-certified facility and offer a cost-effective alternative to genuine parts without sacrificing quality.
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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