Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP 2-Stroke Outboards (Replaces 77177A3, 46-77177A3)

Water Pump Impeller Kit – Fits Mercury/Mariner 30-70 HP 2-Stroke Outboards (Replaces 46-77177A3)

This water pump impeller repair kit is designed for a wide range of Mercury and Mariner 2-stroke outboard motors from 30 HP to 70 HP (1977-1997). It provides all necessary components for a complete overhaul of your engine's lower unit water pump assembly, ensuring reliable cooling performance.

This kit is a direct replacement for Mercury OEM part numbers 46-77177A3 and 77177A3.

• Complete Repair Kit: Includes the impeller, upper housing, base, face plate, gaskets, seals, and all other required hardware for a full replacement.
• Durable Construction: The housing is manufactured from high-strength Nylon PA66 plastic to meet or exceed OEM specifications for longevity and performance.
• Installation Location: Designed for installation in the lower unit (gearcase) of the outboard motor.

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 Impeller (47-89983T/89983T)
• 1 x Upper Pump Housing (77822A1)
• 1 x Water Pump Base (46-77177A1)
• 1 x Drain Gasket (12-20260)
• 1 x Lower Water Pump Base to Face Plate Gasket (27-19553)
• 1 x Upper Face Plate to Body Gasket (27-32770/27-19551)
• 1 x Water Pump Base Gasket (27-32771)
• 1 x Water Pump Base Gasket (27-77417/27-19552)
• 1 x Drain Plug (12-49221-1)
• 1 x Face Plate (32768/54705)
• 1 x O-Ring (25-26722)
• 1 x Impeller Key (8M0032837)
• 1 x Rubber Washer (25-20273)
• Various seals and additional O-rings

Installation Guide

1. Safety First: Disconnect the battery and remove the ignition key.
2. Drain Gearcase Lube: Place a drain pan under the lower unit and remove the upper and lower gear lube drain screws. Allow the oil to drain completely.
3. Remove Lower Unit: Remove the bolts securing the lower unit (gearcase) to the engine's mid-section. Carefully lower the unit.
4. Access the Water Pump: With the lower unit removed, locate and unbolt the water pump housing.
5. Remove Old Components: Remove the old housing, impeller, face plate, and gaskets. Take note of their orientation.
6. Clean and Inspect: Thoroughly clean all mating surfaces and inspect the driveshaft for any scoring or wear.
7. Install New Gaskets: Place the new gaskets onto the water pump base.
8. Install New Impeller: Slide the new impeller key into the driveshaft and install the new impeller, turning the driveshaft clockwise to seat the vanes correctly.
9. Install Housing: Position the new housing and face plate, then tighten the bolts to the manufacturer's specified torque.
10. Reinstall Lower Unit: Carefully guide the lower unit back into place, ensuring the driveshaft and water tube align. Secure with the mounting bolts.
11. Refill Gearcase: Reinstall the lower drain screw and pump fresh gear lube in through the bottom hole until it flows out the upper vent hole. Reinstall the upper screw.
12. Test Operation: Reconnect the battery. Start the engine using a water supply (flushing muffs) and verify a strong, steady stream from the "tell-tale" outlet.

Troubleshooting & FAQ

How do I confirm this fits my engine?

The most reliable method is to check your engine's serial number against the ranges listed in the "Compatible Engine Models" table above. While your model and year may be listed, serial number is the best check for older engines.

What are the signs of a failing water pump impeller?

Common symptoms include a weak or non-existent water stream from the "tell-tale" outlet at the back of the engine, and the engine overheating alarm sounding. Reduced engine performance at high speeds can also be a sign.

How often should I replace the water pump impeller?

For most recreational boaters, it is recommended to replace the impeller and gaskets every 1-2 years or every 100-200 hours of use, whichever comes first. This prevents the rubber from degrading and failing, which can cause severe engine damage.

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.