47-89981 Water Pump Impeller for Mercury Mariner 4HP 4.5HP 6HP 7.5HP 9.8HP | JLM Marine

Water Pump Impeller for Mercury Mariner 4HP 4.5HP 6HP 7.5HP 9.8HP Outboard

This high-quality aftermarket water pump impeller is designed to fit Mercury Mariner 2-Stroke outboards from 4HP to 9.8HP, covering models manufactured between 1966 and 1978. Engineered for reliable cooling system performance, this impeller ensures your engine operates at optimal temperature during every outing.

Direct replacement for OEM part numbers 47-89981, 47-65957, and 8M0032835, providing a cost-effective solution without compromising quality. Built from durable rubber and metal construction, this impeller delivers consistent flow and long-lasting service.

• Includes impeller with key/pin for complete installation
• Fits engines with 0.456" shaft diameter
• Easy installation with durable, stable construction

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 × Outboard Rubber Impeller with Key/Pin

Installation Guide

1. Disconnect the fuel line and turn off the engine, allowing it to cool completely before starting work.
2. Remove the lower unit by loosening the mounting bolts and carefully separating it from the gear housing.
3. Locate and remove the water pump housing cover by unscrewing the retaining bolts.
4. Carefully extract the old impeller from the pump housing, noting the direction of the vanes. Clean the housing thoroughly, removing any debris or old gasket material.
5. Lubricate the new impeller with water pump grease or soapy water to ease installation.
6. Insert the drive key/pin into the impeller shaft slot, ensuring it sits securely in place.
7. Install the new impeller into the housing, aligning the vanes in the same direction as the old impeller (typically counterclockwise).
8. Reinstall the water pump housing cover with a new gasket, tightening bolts in a crisscross pattern to ensure even sealing.
9. Reattach the lower unit to the outboard, ensuring all mounting bolts are torqued to manufacturer specifications.
10. Reconnect the fuel line and test the engine in a water tank or on-water to verify proper water flow from the telltale indicator.

Troubleshooting & FAQ

Q: How do I confirm this impeller fits my Mercury outboard?
A: Verify your engine's horsepower, model number, and serial number against the compatibility table above. The impeller fits 4HP to 9.8HP Mercury Mariner 2-stroke engines with serial numbers within the specified ranges (1966-1978). You can also cross-reference OEM part numbers 47-89981, 47-65957, or 8M0032835.

Q: How often should I replace my water pump impeller?
A: We recommend inspecting the impeller annually and replacing it every 2-3 years or 200-300 hours of operation, whichever comes first. If you notice overheating, weak water flow from the telltale, or visible damage to the vanes during inspection, replace it immediately regardless of usage time.

Q: What are the signs that my impeller has failed?
A: Common symptoms include engine overheating, reduced or no water discharge from the telltale (pilot hole), steam coming from the engine, or a high-temperature alarm. If you experience any of these issues, stop the engine immediately and inspect the impeller for cracked, broken, or missing vanes.

Q: What's the difference between this impeller and the original Mercury part?
A: This is a high-quality aftermarket replacement built to OEM specifications using comparable rubber and metal materials. While it is not an OEM Mercury component, it is manufactured in an ISO9002-certified facility and tested to deliver reliable cooling performance at a more competitive price point.

Q: Do I need any special tools to install this impeller?
A: Basic hand tools are typically sufficient—wrenches, screwdrivers, and a lower unit removal tool set. You'll also need water pump grease or soapy water for lubrication, and a new water pump gasket kit is recommended. Refer to your engine's service manual for specific torque specifications.

Q: Is this an OEM or aftermarket part?
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.