Water Pump Impeller – Fits Mercury Marine 4-9.8 HP 2-Stroke Outboards (Replaces 47-89981)

Water Pump Impeller – Fits Mercury Marine 4-9.8 HP 2-Stroke Outboards (Replaces 47-89981)

This water pump impeller is a direct-fit replacement for various Mercury Marine 2-stroke outboard motors, including 4, 4.5, 6, 7.5, and 9.8 HP models. It is engineered from durable, high-quality neoprene with a brass hub to ensure reliable performance and longevity in marine environments.

This component is a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 47-89981, 47-65957, and 47-39074, as well as Sierra 18-3039.

• Material: Constructed from tough neoprene with a solid brass hub for corrosion resistance.
• Installation: Designed as a direct replacement part that fits in the stock water pump housing.
• Important Fitment Note: This impeller has an internal diameter of 0.456 inches and is not compatible with 5 HP Mercury Mariner engines.

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 (47-89981)

Installation Guide

1. Disconnect the battery and remove the engine cover.
2. Drain the gear lube from the lower unit.
3. Remove the bolts securing the lower unit (outdrive) to the engine.
4. Carefully separate and lower the drive unit to access the water pump.
5. Unbolt the water pump housing to expose the impeller.
6. Note the rotational direction of the existing impeller blades before removing it.
7. Clean the housing interior and inspect all surfaces for wear or damage.
8. Apply a light coat of marine grease to the new impeller and the inside of the housing.
9. Install the new impeller, turning the driveshaft clockwise to help fold the blades into the correct orientation.
10. Reassemble the pump housing, ensuring all seals are correctly seated.
11. Reinstall the lower unit and refill it with the correct grade of gear lube.
12. Connect a water supply (flushing muffs) to the lower unit and test the engine to confirm proper water flow.

Troubleshooting & FAQ

How do I know this impeller will fit my Mercury outboard?

This impeller is designed for select Mercury 4, 4.5, 6, 7.5, and 9.8 HP 2-stroke models. It has an internal shaft diameter of 0.456 inches (11.58 mm). Please review the compatible models table and your engine's serial number range to confirm fitment. Crucially, it will not fit 5 HP Mercury Mariner engines.

What are the signs of a failing water pump impeller?

Common signs include a weak or non-existent water stream from the "telltale" outlet, engine overheating alarms, or reduced engine performance. Visible signs of damage like cracked, stiff, or broken blades on the old impeller also indicate it is time for a replacement.

How often should I replace my water pump impeller?

As a best practice, inspect your impeller annually and replace it every 1-2 years or every 100-200 hours of use, depending on operating conditions. If you frequently operate in sandy, silty, or saltwater, more frequent replacement is recommended to maintain cooling system performance.

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.