Water Pump Repair Kit for Mercury/Mariner 30–70 HP 2-Stroke Outboards – Replaces 77177A3 and 46-77177A3
Water Pump Repair Kit for 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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Delivery and Shipping
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Water Pump Repair Kit for Mercury/Mariner 30–70 HP 2-Stroke Outboar...
Water Pump Repair Kit for 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 complete water pump repair kit is designed to service the cooling system on select Mercury and Mariner 2-stroke outboard motors from 30 to 70 HP. The listed applications cover models manufactured from 1977 through 1997, subject to the engine model and serial-number ranges shown below.
The kit is listed as a replacement for Mercury/Mariner part numbers 77177A3 and 46-77177A3. Related aftermarket reference numbers include Sierra 18-3324, GLM 12100, and Mallory 9-48312.
- Aftermarket replacement water pump repair kit for selected Mercury and Mariner outboards.
- Includes pump housings, impeller, face plate, gaskets, drain components, and O-rings listed in the package contents.
- Intended for standard 2-stroke outboard water-pump service applications within the specified fitment ranges.
Part Number Matrix
Use these numbers to compare the listed OEM and aftermarket references with the part being replaced.
| Brand | Part Number |
|---|---|
| Mercury/Mariner | 77177A3 |
| Mercury/Mariner | 46-77177A3 |
| Sierra | 18-3324 |
| GLM | 12100 |
| Mallory | 9-48312 |
Engine & Model Compatibility
This kit is intended for select Mercury and Mariner 2-stroke outboards. Confirm the engine brand, horsepower, stroke, model details, and complete serial number before ordering. Serial-number boundaries are important because water-pump designs can change within the same horsepower range.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Serial-Number Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | Outboard | 30 HP Jet | 2-Stroke | 1977–1997 | 77177A3 | C159200–G589999 |
| Mercury/Mariner | Outboard | 35 HP | 2-Stroke | 1977–1997 | 77177A3 | 6445653 and later |
| Mercury/Mariner | Outboard | 40 HP | 2-Stroke | 1977–1997 | 77177A3 | 4890103–6445653 |
| Mercury/Mariner | Outboard | 40 HP, 4-cylinder | 2-Stroke | 1977–1997 | 77177A3 | C159200 and later |
| Mercury/Mariner | Outboard | 45 HP | 2-Stroke | 1977–1997 | 77177A3 | 5531630 and later |
| Mercury/Mariner | Outboard | 50 HP, 4-cylinder | 2-Stroke | 1977–1997 | 77177A3 | 4962056 and later |
| Mercury/Mariner | Outboard | 50 HP, 3-cylinder | 2-Stroke | 1977–1997 | 77177A3 | 6428681–D000749 |
| Mercury/Mariner | Outboard | 60 HP | 2-Stroke | 1977–1997 | 77177A3 | 6428681–D000749 |
| Mercury/Mariner | Outboard | 65 HP, 3-cylinder | 2-Stroke | 1977–1997 | 77177A3 | 4382057–4571651 |
| Mercury/Mariner | Outboard | 70 HP | 2-Stroke | 1977–1997 | 77177A3 | 4977157–B110053 |
Technical Specifications
- Product Type
- Complete water pump repair kit
- Application
- Selected Mercury and Mariner 2-stroke outboards
- Horsepower Range
- 30–70 HP, including the listed 30 HP Jet application
- Model Years
- 1977–1997 applications as listed
- Installation
- Replacement service for the original water-pump components
- Product Status
- Aftermarket replacement; not an OEM component
What’s in the Box
- 1 × Upper pump housing, 18-3118
- 1 × Lower pump housing/water-pump base, 18-3424
- 1 × Impeller, 18-3007
- 1 × Face plate, 18-3107
- 1 × Drain gasket, 18-2945
- 1 × Lower water-pump base-to-face-plate gasket, 18-2823
- 1 × Upper face-plate-to-body gasket, 18-2824
- 1 × Water-pump base gasket, 18-2825
- 1 × Water-pump base gasket, 18-2841
- 1 × Drain plug, 18-2948
- 1 × O-ring, 18-7155
- 1 × O-ring, 18-7174
- 1 × O-ring, 18-7115
The drive key is not listed as a separate kit component. Inspect and reuse the original key only if it is in serviceable condition, or replace it with the correct key for the engine.
Installation Notes
- Disconnect the battery and shift linkage, following the engine manufacturer’s service procedures.
- Unbolt and carefully remove the lower unit from the outboard leg.
- Remove the water-pump housing bolts and lift the pump assembly from the driveshaft.
- Remove the old impeller, noting the position of the drive key. Remove the old gaskets, face plate, and related sealing components.
- Clean all mating surfaces and remove old gasket material, deposits, and corrosion.
- Install the applicable new gaskets, face plate, and serviceable drive key.
- Install the new impeller and rotate the driveshaft clockwise while seating the impeller vanes in the housing.
- Install the new pump housing and tighten the fasteners to the manufacturer’s specified torque in a crisscross pattern.
- Apply an appropriate light coat of marine grease to the driveshaft splines and reinstall the lower unit, aligning the water tube, driveshaft, and shift shaft.
- Reconnect the shift linkage and battery. Run the engine only with an adequate water supply, then confirm a steady tell-tale stream and check for leaks or overheating.
Troubleshooting & FAQ
How do I know if my water pump is failing?
Common signs include a weak or absent tell-tale stream, an overheating warning, reduced cooling performance at higher engine speed, or a damaged, melted, or deformed pump housing.
How often should the impeller be inspected or replaced?
Inspect the impeller according to the engine manufacturer’s service schedule. Many operators inspect it annually and replace it based on operating hours and conditions, especially after use in saltwater, sand, or silty water.
My horsepower is listed, but my serial number is different. Will this kit fit?
Not necessarily. Serial-number ranges identify important design changes. Compare the complete engine serial number and model information with the table before ordering. If the range does not match, confirm the application with a qualified marine-parts specialist.
Is this a complete kit?
This listing is for a complete water-pump repair kit containing the housings, impeller, face plate, gaskets, drain component, and O-rings listed in the “What’s in the Box” section. The drive key is not listed as an included component.
Is this OEM or aftermarket?
This is an aftermarket replacement kit, not an OEM Mercury or Mariner component. The listed OEM and aftermarket part numbers are reference numbers for application comparison.
What should I do if I am unsure about fitment?
Compare the original pump components, engine model, horsepower, stroke, year, and complete serial number before purchase. Do not rely on horsepower alone when the serial-number range is different.
Safety & Important Information
- Verify the engine model, year, horsepower, stroke, and complete serial number before ordering.
- Compare the original pump assembly and component configuration with the kit contents.
- Do not operate the outboard without an adequate water supply.
- Follow the manufacturer’s service manual for torque specifications, sealants, lubrication, and lower-unit installation procedures.
- Professional installation is recommended when the required service procedures or alignment checks are unfamiliar.
About Sea Sierra
- Marine Replacement Parts — We supply aftermarket components for common marine service and repair applications.
- Application-Focused Listings — Fitment information is organized by brand, horsepower, stroke, model year, and serial-number range where available.
- Support Before Ordering — Confirm your complete engine details when an application falls outside the listed ranges.
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