Water Pump Impeller Repair Kit – Fits Mercury Marine 4–9.8 HP (Replaces 46-70941A3)

Water Pump Impeller Repair Kit – Fits Mercury Marine 4–9.8 HP (Replaces 46-70941A3)

This water pump impeller repair kit is designed for Mercury Marine 4 HP, 4.5 HP, 7.5 HP, and 9.8 HP 2-Stroke outboard motors made between 1975 and 1986. It provides a reliable solution for maintaining your engine’s cooling system.

This kit serves as a direct replacement for several OEM and aftermarket part numbers, including Mercury 46-70941A3, Sierra 18-3446, GLM 12122, and QuickMarine 70941A3.

• Complete Kit: Includes the impeller, housing, face plate, gaskets, and seals needed for a full service.
• Easy Installation: Designed as a direct-fit replacement for the original factory parts.
• Durable Materials: Features a CR-Neoprene impeller and a stainless steel face plate for corrosion resistance and longevity.

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
• 1 x Impeller Plate (Face Plate)
• 1 x Water Pump Cover Seal
• 1 x Cover Assembly
• 1 x Housing Assembly
• 1 x Key
• 1 x Seal
• 1 x Washer
• 1 x O-ring (25-62704, 29439)
• 1 x Rubber Ring (26-30526)
• 1 x Oil Seal O-ring (26-30913)

Installation Guide

1. Disconnect the negative battery cable and shift the outboard into the neutral position.
2. Remove the bolts securing the lower unit (gearcase) and carefully lower it from the engine.
3. Unbolt and remove the water pump housing to access the old impeller and gaskets.
4. Remove the old impeller, key, face plate, and seals, noting their orientation.
5. Thoroughly clean all mating surfaces on the driveshaft and housing assembly.
6. Install the new gaskets and the stainless steel face plate.
7. Insert the new key into the driveshaft and slide the new impeller on while turning the shaft clockwise to bed the vanes.
8. Install the new housing and cover assembly, ensuring all seals are seated correctly.
9. Tighten the housing bolts to the manufacturer's specified torque.
10. Reinstall the lower unit onto the upper housing and securely fasten the bolts.
11. Reconnect the battery and start the engine using a water supply (flushing muffs), confirming a steady water stream from the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this fits my engine?

Check your engine's model, year, and serial number against the ranges provided in the "Compatible Engine Models" table. This kit is specifically designed for Mercury 4–9.8 HP 2-Stroke outboards from 1975–1986. Using our linked Mercury Serial Number Guide can help you verify fitment.

What are the signs of a failing water pump impeller?

Common symptoms include a weak or no water stream from the engine's tell-tale port, frequent engine overheating alarms, or a noticeable decrease in cooling efficiency, especially at low speeds.

How often should I replace the water pump impeller?

For preventative maintenance, we recommend inspecting the impeller annually and replacing it every 1-2 years or 100-200 hours of operation. Replacement frequency depends on usage, water conditions (saltwater, sandy, or silty water), and storage.

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.