Water Pump Impeller Kit – Fits Mercury/Mariner 2-Stroke 3.9HP-9.8HP (Replaces 47-89981Q1, 47-89981T1)

Water Pump Impeller Kit – Fits Mercury/Mariner 2-Stroke 3.9HP-9.8HP (Replaces 47-89981Q1, 47-89981T1)

This kit is designed for Mercury/Mariner 2-Stroke outboard engines, including 3.9HP, 4HP, 4.5HP, 6HP, 7.5HP, and 9.8HP models, primarily from the 1970s and 1980s.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring wide compatibility for a complete water pump repair or rebuild.

• Direct replacement installation.
• Engineered for a 0.456" ID driveshaft connection.
• Includes one high-quality water pump impeller.

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 (47-89981Q1/47-89981T1/89981T2)

Installation Guide

1. Safety First: Disconnect the battery and ensure the engine is fully stopped before beginning work.
2. Access the Pump: Remove the lower unit (gearcase) from the outboard motor to access the water pump assembly.
3. Disassemble Housing: Carefully unbolt and lift the water pump housing off the driveshaft. Keep track of bolt order if they differ in length.
4. Remove Old Impeller: Note the rotational direction of the old impeller's vanes. Remove the old impeller, woodruff key, gaskets, and wear plate.
5. Clean and Inspect: Thoroughly clean all surfaces of the housing and base. Check the housing and wear plate for scoring, warping, or corrosion and replace if damaged.
6. Install New Components: Place the new gaskets and wear plate. Insert the woodruff key into the driveshaft and slide the new impeller on, rotating the driveshaft in the clockwise direction to bend the vanes correctly.
7. Reassemble: Apply a light coat of marine grease to the inside of the housing. Press the housing down over the impeller while turning the driveshaft clockwise and secure it with the bolts.
8. Reinstall Lower Unit: Reattach the lower unit to the outboard engine, ensuring the driveshaft and shift shaft are correctly aligned.
9. Test Operation: Reconnect the battery. Start the engine in water and verify a strong, steady stream of water is exiting the telltale outlet.

Troubleshooting & FAQ

How do I confirm this kit fits my specific engine model?

Check the "Compatible Engine Models" table and cross-reference your engine's serial number. This kit is specifically for Mercury/Mariner 2-stroke models from 3.9HP to 9.8HP. For additional help, use the linked Mercury serial number guide to verify your engine details before ordering.

What are the signs of a failing water pump impeller?

Common signs include the engine overheating, a weak or non-existent water stream from the "telltale" outlet, and a melted water pump housing. Upon inspection, the old impeller may have visible cracks, be brittle, or have missing vanes.

How often should I replace my impeller?

For preventative maintenance, we recommend replacing the impeller every 1-2 years or every 100-200 hours of operation. Service intervals should be shorter if operating in saltwater or sandy/silty 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.