Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP (Replaces 77177A3, 46-77177A3)
Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP (Replaces 77177A3, 46-77177A3) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP (Replaces 7...
Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP (Replaces 77177A3, 46-77177A3) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit is designed for Mercury and Mariner 30–70 HP 2-stroke outboard engines manufactured between 1977 and 1997. It ensures your engine's cooling system functions efficiently, preventing overheating and potential damage.
The kit serves as a direct replacement for Mercury part numbers 77177A3 and 46-77177A3, as well as Sierra 18-3324 and GLM 12100, providing a comprehensive solution for your maintenance needs.
- Engineered as a direct-fit replacement for specified models.
- Installation can be performed with standard marine service tools.
- Includes all essential components for a complete water pump rebuild.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Mercury | 77177A3 |
| Mercury | 46-77177A3 |
| Sierra | 18-3324 |
| GLM | 12100 |
Engine & Model Compatibility
Confirm your engine model and year in the table below to ensure accurate fitment.
This kit is compatible with 2-stroke outboard models from Mercury and Mariner.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Mercury | 30 HP | 30 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mercury | 35 HP | 35 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mercury | 40 HP | 40 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mercury | 45 HP | 45 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mercury | 50 HP | 50 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mercury | 60 HP | 60 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mercury | 65 HP | 65 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mercury | 70 HP | 70 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mariner | 30 HP | 30 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mariner | 35 HP | 35 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mariner | 40 HP | 40 | 2-Stroke | 1977–1997 | 77177A3/46-7717A3 |
| Mariner | 45 HP | 45 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mariner | 50 HP | 50 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mariner | 60 HP | 60 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mariner | 65 HP | 65 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
| Mariner | 70 HP | 70 | 2-Stroke | 1977–1997 | 77177A3/46-77177A3 |
Technical Specs
- Product Type
- Water Pump Impeller Kit
- Installation
- Direct Replacement
- Housing Material
- Rubber (Impeller), Metal (Housing)
- Housing Color
- Black
- Warranty
- Varies by manufacturer
- Other Technical Attributes
- Includes complete water pump rebuild kit with housing
What’s in the Box
- 1 x Water Pump Impeller
- 1 x Drive Key
- 1 x Impeller Plate
- 1 x Gaskets Set
- 1 x Water Pump Housing
Installation Notes
- Disconnect the battery and shift the outboard into neutral.
- Drain the gearcase lubricant from the lower unit.
- Remove the mounting bolts securing the lower unit (gearcase) to the engine.
- Carefully lower and separate the gearcase from the drive shaft housing.
- Unbolt and remove the old water pump housing assembly.
- Clean the mounting surfaces and inspect the driveshaft for wear or damage.
- Assemble the new impeller, key, plate, gaskets, and housing from the kit. Lubricate the impeller and housing interior with a suitable marine grease.
- Install the new water pump assembly onto the driveshaft and bolt it into place.
- Realign the driveshaft, water tube, and shift shaft, then reinstall the lower unit.
- Refill the gearcase with new lubricant according to manufacturer specifications.
- Reconnect the battery and test the engine in the water, confirming a steady stream of water from the tell-tale outlet.
Troubleshooting & FAQ
How do I know if my water pump is failing?
Common signs include a weak or nonexistent water stream from the "tell-tale" outlet, engine overheating alarms, or a noticeable decrease in engine performance. A visual inspection may reveal a melted housing or impeller blades that are cracked, brittle, or have taken a set.
How often should the water pump impeller be replaced?
For preventative maintenance, it is recommended to inspect the impeller annually and replace it every 2-3 years or every 200-300 hours of operation, whichever comes first. This interval can be shorter in saltwater or silty/sandy conditions.
Is this kit difficult to install?
Installation is straightforward for those with mechanical experience and the correct tools. It involves removing the lower unit of the outboard. If you are not comfortable with this process, professional installation is recommended.
Why does this kit include a new housing?
An old or scored housing can reduce pumping efficiency and cause premature wear on the new impeller. Replacing the housing along with the impeller ensures a tight seal and optimal cooling performance, extending the life of the repair.
My engine model is listed, but my part looks different. What should I do?
Do not install the part. Manufacturers sometimes make mid-year changes. Always compare the new parts in the kit to your old parts before installation. If they do not match, contact us for assistance.
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 and specifications against 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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