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

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

This water pump impeller repair kit is designed for Mercury Outboard 4, 4.5, 7.5, and 9.8 HP 2-Stroke engines (1975–1986). It provides a reliable solution for maintaining your engine’s cooling system for optimal performance and longevity.

This assembly is a direct replacement for Mercury part numbers 46-70941A3 / 70941A3, Sierra 18-3446, and GLM 12122.

• Installation Type: Direct replacement for a hassle-free installation.
• Complete Kit: Includes the impeller, housing, plate, gaskets, and seals for a full overhaul.
• Durable Materials: Features a neoprene rubber impeller and a high-strength PA66 nylon housing for extended service life.

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 Housing, Water Pump Assembly (70941T01, 70941A1)
• 1 x Cover (93224A1)
• 1 x Face Plate (46895)
• 1 x Cup, Insert (70977T, 70977)
• 1 x Water Pump Impeller (89981)
• 1 x Key (8M0032835, 56655)
• 1 x Seal (36558)
• 1 x O-ring (25-62704, 29439)
• 1 x Rubber Ring (26-30526)
• 1 x Oil Seal O-ring (26-30913)
• 1 x Washer

Installation Guide

1. Safety First: Disconnect the negative battery cable and remove the spark plug wires.
2. Access Lower Unit: Place the outboard in neutral gear. Unbolt and carefully lower the gearcase (lower unit) from the engine leg.
3. Disassemble Pump: Locate the water pump assembly on top of the lower unit. Remove the bolts securing the pump housing.
4. Remove Old Components: Lift off the housing and pull the old impeller off the driveshaft. Remove the wear plate, gaskets, and seals. Clean all mating surfaces of any old gasket material or debris.
5. Install New Key: Place the new drive key into the slot on the driveshaft.
6. Install New Impeller: Slide the new impeller onto the driveshaft over the key. Apply a light coat of marine grease to the inside of the new housing.
7. Seat the Impeller: Install the new housing over the impeller, rotating the driveshaft clockwise to correctly flex the impeller vanes.
8. Reassemble: Secure the new housing with its bolts, tightening them to the manufacturer's recommended torque.
9. Reinstall Lower Unit: Carefully guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube are properly aligned. Secure with the mounting bolts.
10. Final Checks: Reconnect the battery. Start the engine using a water supply (flushing muffs) and check for a strong, steady stream from the tell-tale port.

Troubleshooting & FAQ

How do I confirm this fits my engine?
Check the "Compatible Engine Models" table and match your engine's model, HP, and year range. For Mercury engines, it is critical to also verify your serial number against the ranges listed in the 'Notes' column to ensure an exact match.

What are the signs of a failing water pump impeller?
Common signs include a weak or non-existent water stream from the tell-tale outlet, engine overheating alarms, a reduction in engine power, and steam or excess exhaust smoke.

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 every 100-200 hours of use. Service intervals should be shorter if operating in sandy, silty, or saltwater conditions.

What is the difference between this aftermarket kit and the OEM part?
This kit is engineered to meet or exceed original equipment (OEM) specifications for fit, form, and function. The impeller is made from durable neoprene rubber, and the housing is crafted from high-strength PA66 nylon, offering a reliable, high-performance alternative to OEM parts at a competitive price.

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.