Water Pump Impeller Kit – Fits Mercury/Mariner 30–70 HP 2-Stroke Outboards, Replaces 77177A3 and 46-77177A3
Water Pump Impeller Kit – Fits Mercury/Mariner 30–70 HP 2-Stroke Outboards, Replaces 77177A3 and 46-77177A3 is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller Kit – Fits Mercury/Mariner 30–70 HP 2-Stroke Ou...
Water Pump Impeller Kit – Fits Mercury/Mariner 30–70 HP 2-Stroke Outboards, Replaces 77177A3 and 46-77177A3 is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit is intended for selected Mercury and Mariner 30–70 HP 2-stroke outboard applications. It is designed to restore water-pump performance and help maintain proper cooling-system water flow when the original impeller or related pump components are worn.
The kit is listed as a replacement for Mercury part numbers 77177A3 and 46-77177A3. Sierra 18-3324 and GLM 12100 are additional aftermarket reference numbers associated with this application. Always verify the engine model, year, serial-number range, and the original pump components before ordering.
- Replacement water-pump impeller kit for selected Mercury and Mariner outboards.
- Applicable to listed 30–70 HP 2-stroke applications; model and serial-number verification is required.
- Designed for service or replacement of worn water-pump components.
- Use the included parts only where they match the original assembly and the applicable service information.
Part Number Matrix
Use these references to compare the replacement with the part removed from your outboard. A reference number alone does not confirm every model, year, shaft configuration, or serial-number range.
| Brand | Part Number |
|---|---|
| Mercury | 77177A3 |
| Mercury | 46-77177A3 |
| Sierra | 18-3324 |
| GLM | 12100 |
Engine & Model Compatibility
The application is listed for Mercury and Mariner 30–70 HP 2-stroke outboards manufactured from 1977 through 1997. This broad range may include model-specific or serial-number-specific variations. Confirm the complete engine designation, production year, serial number, stroke type, and original water-pump configuration before installation.
| Brand | Rated HP | Stroke | Listed Years | Reference Part Numbers |
|---|---|---|---|---|
| Mercury | 30 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mercury | 35 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mercury | 40 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mercury | 45 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mercury | 50 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mercury | 60 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mercury | 65 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mercury | 70 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mariner | 30 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mariner | 35 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mariner | 40 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mariner | 45 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mariner | 50 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mariner | 60 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mariner | 65 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
| Mariner | 70 HP | 2-Stroke | 1977–1997 | 77177A3 / 46-77177A3 |
Technical Specs
- Product Type
- Water pump impeller kit
- Application
- Selected Mercury and Mariner 30–70 HP 2-stroke outboards
- Installation
- Replacement service part; fitment must be verified before installation
- Impeller Material
- Rubber
- Housing
- Included in the listed kit configuration
- Reference Numbers
- Mercury 77177A3 and 46-77177A3; Sierra 18-3324; GLM 12100
What’s in the Box
- 1 × Water pump impeller
- 1 × Drive key
- 1 × Impeller plate
- 1 × Gasket set
- 1 × Water-pump housing
Component appearance and exact gasket configuration can vary by application. Compare every supplied component with the original parts before beginning installation.
Installation Notes
- Disconnect the battery and place the outboard in neutral.
- Drain the gearcase lubricant from the lower unit if required by the service procedure.
- Remove the mounting hardware securing the lower unit to the engine.
- Lower the gearcase carefully, keeping the driveshaft, water tube, and shift-shaft components supported.
- Remove the old water-pump housing and related components.
- Clean the mating surfaces and inspect the driveshaft, water tube, keyway, plate, and housing for wear or damage.
- Install the replacement plate, gasket, key, impeller, and housing in the correct order for the specific engine.
- Use an appropriate lubricant or assembly method specified by the engine service manual; do not substitute unsuitable grease or sealant.
- Reinstall the water-pump assembly and torque fasteners according to the manufacturer’s service specifications.
- Realign the driveshaft, water tube, and shift shaft, then reinstall the lower unit.
- Refill the gearcase with the correct lubricant if it was drained.
- Run the engine using the manufacturer-approved procedure and confirm a consistent cooling-water tell-tale stream before normal operation.
Troubleshooting & FAQ
How do I know if my water pump is failing?
Possible symptoms include a weak or absent tell-tale stream, an overheating warning, elevated operating temperature, or visible cracking, brittleness, distortion, or missing vanes on the impeller. Blocked passages and other cooling-system faults can cause similar symptoms.
How often should the water-pump impeller be replaced?
Inspect the impeller according to the engine manufacturer’s maintenance schedule. Replacement intervals depend on operating hours, storage conditions, saltwater exposure, sand or silt, and the condition of the pump housing. Replace it sooner if it is damaged or has taken a permanent set.
Is this kit difficult to install?
Installation normally requires removal of the lower unit and correct realignment of the driveshaft, water tube, and shift shaft. Use the applicable service manual and have the work performed by a qualified marine technician if you are not familiar with outboard lower-unit service.
Why does the kit include a new housing?
A scored, worn, or distorted housing can reduce pump efficiency and accelerate impeller wear. Replacing it with the other listed water-pump components can help restore the intended pump clearances when the application requires those parts.
My engine model is listed, but my original part looks different. What should I do?
Do not install the kit until the difference is resolved. Compare the original parts, engine model, year, and serial number with the applicable service information. Mid-year and serial-number changes can affect water-pump components even within the same horsepower range.
Is this an OEM part?
This listing is for an aftermarket replacement kit, not a Mercury or Mariner branded OEM component. The manufacturer and seller should be identified from the product packaging and order documentation.
Safety & Important Information
- Verify the engine brand, model, horsepower, stroke type, year, and serial-number range before ordering.
- Compare the kit components with the original water-pump assembly before installation.
- Follow the applicable engine service manual for disassembly, torque values, lubrication, sealing, and testing.
- Do not operate the outboard without an adequate cooling-water supply or outside the manufacturer’s approved testing procedure.
- This is an aftermarket replacement, not an OEM component.
About Sea Sierra
- Marine Replacement Parts — Parts are offered for maintenance and repair of recreational marine applications.
- Application-Focused Listings — Product references and fitment information are provided to help with part comparison.
- Installation-Conscious Support — Always verify the original component and applicable service information before installation.
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