Water Pump Impeller Repair Kit – Fits Mercury/Mariner 30-70 HP (Replaces 46-77177A3, 77177A3)

Water Pump Impeller Repair Kit – Fits Mercury/Mariner 30-70 HP

This water pump impeller repair kit is designed for Mercury/Mariner 2-Stroke outboard engines from 30 to 70 HP, model years 1976–1997. It provides a comprehensive solution for restoring your engine's cooling system performance.

This kit serves as a direct replacement for Mercury OEM part numbers 46-77177A3 and 77177A3, as well as aftermarket parts from Sierra, GLM, Mallory, EMP, and Recmar.

• Includes a complete set of components for a full service: new housing, impeller, gaskets, seals, and hardware.
• Features a durable Nylon PA66 plastic housing and a neoprene rubber impeller for reliable performance.
• Installs in the lower unit (gearcase) of the outboard.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x Water Pump Housing (77822A1)
• 1 x Insert (48753)
• 1 x Impeller (89983T)
• 1 x Upper Water Pump Gasket (19551)
• 1 x Lower Water Pump Gasket (19553)
• 1 x Face Plate (32768)
• 2 x Gasket (19552)
• 1 x O-Ring (25-26722)
• 2 x Drain Plug Seal (26-830749)
• 2 x O-Ring (805726)
• 1 x Key (8M0032837)
• 1 x Rubber Seal (25-20273)
• 1 x Shift Bracket Seal (37721001)

Installation Guide

1. Disconnect Power: Disconnect the battery and spark plug wires for safety.
2. Shift to Neutral: Place the outboard in the neutral gear position.
3. Remove Lower Unit: Unbolt and carefully lower the gearcase (lower unit) from the outboard's driveshaft housing. You may need to disconnect the speedometer tube.
4. Access Water Pump: With the lower unit removed, locate and unbolt the water pump housing.
5. Remove Old Components: Remove the pump housing, impeller, wear plate, and old gaskets. Note the orientation of the impeller fins.
6. Clean Surfaces: Thoroughly clean all mating surfaces, removing any old gasket material or corrosion.
7. Install New Gaskets & Plate: Place the new lower gasket and face plate onto the gearcase.
8. Install Impeller: Lightly lubricate the new impeller and housing interior. Slide the new key onto the driveshaft and install the impeller, twisting it clockwise to bend the fins correctly.
9. Install New Housing: Place the upper gasket and new housing over the impeller and bolt it down securely.
10. Reinstall Lower Unit: Guide the driveshaft back into the engine, ensuring the water tube and shift shaft align. Bolt the lower unit back into place.
11. Test Operation: Reconnect the battery and spark plugs. Start the engine in water and immediately check for a steady stream of water from the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?
Verify your engine's model, horsepower, and year against our compatibility table. Most importantly, check your engine's serial number to ensure it falls within the specified ranges listed in the 'Notes' column.

What are the signs of a failing water pump impeller?
Common symptoms include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "tell-tale" outlet, and in some cases, a high-temperature alarm from your console.

How often should I replace the water pump impeller?
As a general maintenance guideline, it is recommended to inspect and/or replace the impeller every 1 to 2 years, or every 100-200 hours of use. This can vary depending on your operating conditions (e.g., saltwater vs. freshwater, sandy/silty water).

OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

How fast do you ship and how much does it cost?
We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

What is your warranty and return policy?
This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.