Water Pump Repair Kit – Fits Mercury/Mariner 2-Cycle 30-70 HP Outboards (Replaces Mercury/Mariner 77177A3)

Product Details

This Water Pump Repair Kit – Fits Mercury/Mariner 2-Cycle 30-70 HP Outboards (Replaces 77177A3) is a complete assembly designed to restore the cooling system on Mercury and Mariner 2-cycle outboards from 30 HP to 70 HP, generally covering models from 1977 to 1997. It ensures your engine maintains optimal temperature, preventing overheating and potential damage.

This kit provides a direct interchange for OEM part numbers Mercury/Mariner 77177A3 and 46-77177A3, as well as aftermarket references Sierra 18-3324, GLM 12100, and Tutoroto 77177A3.

• Installation: Engineered for direct replacement of the original housing and components.
• Engine Compatibility: Specifically for 2-cycle gasoline outboard engines.
• Complete Kit: Includes the impeller, upper and lower housings, gaskets, and all necessary seals and keys for a comprehensive service.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Compatibility for Mercury and Mariner outboards is detailed below. For many models, checking your engine's serial number against the listed ranges is crucial for ensuring a precise fit.

Technical Specs

Product Type

Water Pump Repair Kit with Housing

Installation

Direct replacement

Fuel Type

Gasoline (2-Cycle)

Housing Material

Rubber/Metal components

Housing Color

Black

Warranty

Varies by manufacturer (Lifetime warranty on aftermarket kits)

Other Technical Attributes

Complete kit including impeller, upper and lower housings, face plate, gaskets, drive key, face seal, seal carrier, and water tube coupling

What’s in the Box

• 1 x Water Pump Impeller
• 1 x Upper Housing
• 1 x Lower Housing
• 1 x Face Plate
• 1 x Face Seal
• 1 x Seal Carrier
• 1 x Water Tube Coupling
• 1 x Drive Key
• Multiple x Gaskets

Installation Notes

1. Safety first: Disconnect the battery and spark plug wires before beginning work.
2. Place a drain pan under the lower unit and remove the gearcase drain and vent screws to empty the lubricant.
3. Remove the bolts securing the lower unit (gearcase) to the outboard's leg and carefully lower it.
4. Unbolt and detach the old water pump housing assembly from the gearcase.
5. Thoroughly clean the driveshaft and all mating surfaces to remove old gasket material and corrosion.
6. Slide the new impeller key into the driveshaft and install the new impeller, ensuring the vanes are oriented correctly (typically clockwise).
7. Assemble the new housings, gaskets, and seals according to your service manual's diagram. Lightly grease components as specified.
8. Re-install the complete water pump assembly onto the gearcase and torque bolts to manufacturer specifications.
9. Guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align correctly. Secure with mounting bolts.
10. Refill the gearcase with the correct type and amount of marine gear lubricant.
11. Reconnect the battery and spark plugs. Test the engine in water, confirming a steady stream from the tell-tale outlet.

Troubleshooting & FAQ