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 kit is designed for Mercury Marine 4 HP, 4.5 HP, 7.5 HP, and 9.8 HP 2-Stroke outboard motors manufactured 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, ensuring broad compatibility for the specified engine models.

• Engineered for direct, hassle-free installation.
• Compatible with specified 2-Stroke Mercury outboard engines.
• Includes the essential components for a complete water pump service.

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

Installation Guide

1. Disconnect the negative battery cable and remove the engine cover.
2. Place the gear selector in neutral and unbolt the shift linkage.
3. Remove the lower unit mounting bolts and carefully lower the gearcase assembly from the driveshaft housing.
4. Unscrew the bolts holding the water pump housing cover and lift it off.
5. Note the rotational direction of the old impeller's vanes before removing it.
6. Remove the old impeller, gaskets, and wear plate from the housing.
7. Thoroughly clean all mating surfaces, removing any old gasket material or debris.
8. Install the new wear plate and gaskets.
9. Lightly lubricate the new impeller and the inside of the pump housing with marine grease.
10. Install the new impeller, turning the driveshaft in its normal direction of rotation to bend the vanes correctly.
11. Secure the pump housing, tighten the bolts to the manufacturer-specified torque, and reattach the lower unit.
12. Reconnect the shift linkage and battery cable, start the engine with a proper water supply, and confirm water is exiting the tell-tale port.

Troubleshooting & FAQ

How do I confirm this fits my engine?

First, check your engine's horsepower, model, and year against the "Compatible Engine Models" table. For Mercury owners, we highly recommend using the official Mercury Serial Number Guide to verify your exact model before ordering.

What are the signs of a failing water pump impeller?

Common symptoms include the engine running hotter than normal or overheating, a weak or no water stream from the "tell-tale" exhaust port, or a melted water pump housing. Upon inspection, a worn impeller may have cracked, brittle, or missing vanes.

How often should I replace my impeller?

For preventative maintenance, it is best practice to replace the water pump impeller every 1 to 2 years or every 100-200 hours of operation, whichever comes first. More frequent changes may be necessary if you operate in sandy, silty, or saltwater conditions.

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.