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

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

This aftermarket water pump impeller is designed for a range of Mercury and 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, helping to restore your engine’s cooling system performance.

This impeller directly replaces Mercury part numbers 47-89981Q1, 47-89981T1, and 89981T2, as well as aftermarket equivalents like Sierra 18-3039, GLM 12270, and Mallory 9-45035.

• Engineered as a direct replacement for straightforward installation.
• Constructed from durable neoprene rubber with a brass hub for reliable service.
• Designed specifically for models with a 0.456" ID driveshaft.

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

Installation Guide

1. Disconnect the battery and remove the engine cover for safety.
2. Locate and unbolt the lower unit (gearcase) from the outboard's main leg. Take care as it can be heavy.
3. Gently lower the gearcase. You may need to disconnect the shift linkage to fully separate it.
4. Place the gearcase securely on a workbench or stable surface.
5. Unscrew the bolts securing the water pump housing and carefully lift the housing off.
6. Note the rotational direction of the old impeller's blades before sliding it off the driveshaft.
7. Thoroughly clean the inside of the housing and the wear plate, removing any salt deposits, debris, or corrosion.
8. Apply a light coat of marine-grade grease or liquid soap to the new impeller and the interior of the housing.
9. Slide the new impeller onto the driveshaft, turning the shaft clockwise to correctly bend the flexible blades into position.
10. Reinstall the water pump housing, ensuring a proper seal. Tighten the bolts to the manufacturer's recommended torque specification.
11. Carefully guide the lower unit back into place, reconnecting the shift linkage, and secure it by tightening the mounting bolts.

Troubleshooting & FAQ

Q: How do I confirm this impeller fits my engine?
A: First, check your engine's serial number against the ranges listed in the 'Compatible Engine Models' table above. It is also critical to confirm your driveshaft size. This impeller is for driveshafts with a 0.456" inner diameter; a different model is used for 0.438" shafts, so verifying this measurement is essential for correct fitment.

Q: What are the signs of a failing water pump impeller?
A: Common symptoms include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "tell-tale" outlet, or a high-pitched whining sound from the lower unit. Upon inspection, a worn impeller may have cracks, missing blades, or feel stiff and brittle.

Q: How often should I replace my impeller?
A: For preventative maintenance, we recommend replacing the water pump impeller every one to two years, or every 100-200 hours of engine use. This interval should be shortened if you frequently operate in sandy, silty, or saltwater conditions.

Q: OEM vs. Aftermarket?
A: 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.

Q: How fast do you ship and how much does it cost?
A: 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.

Q: What is your warranty and return policy?
A: 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.