Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-85089 10, 821354A2)

Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-85089 10, 821354A2)

This water pump impeller is designed for a broad range of Mercury/Mariner 15-50 HP 2-Stroke & 4-Stroke engines (1984–2006), as well as select Force 15-50 HP 2-Stroke engines (1984–1999). It is also compatible with certain Chrysler/US Marine models that use identical cross-reference parts, ensuring reliable performance for engine cooling systems.

This component serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 47-85089 10, 850893, 850892, and Sierra 18-3057. Refer to the cross-reference table for a complete list.

• Engineered as a direct OEM-equivalent replacement.
• Constructed from high-strength, flexible neoprene rubber for durability.
• Package contains one water pump impeller for a complete replacement.

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 47-85089 10 / 8508910 / 8M0024502)

Installation Guide

A basic installation process is outlined below. Professional installation is always recommended.

1. Disconnect Power: Disconnect the negative battery cable to prevent electrical shorts.
2. Drain Gearcase: Drain the gearcase lubricant to avoid spills.
3. Remove Lower Unit: Unbolt and carefully lower the gearcase/lower unit from the outboard. You may need to disconnect the shift linkage.
4. Access the Impeller: Locate and unbolt the water pump housing cover.
5. Remove Old Impeller: Note the rotational direction of the old impeller vanes. Pry or pull the old impeller off the driveshaft. Remove the old gaskets and wear plate.
6. Clean and Inspect: Thoroughly clean the inside of the pump housing and inspect it for scoring, warping, or corrosion. Replace the housing if significant wear is found.
7. Install New Impeller: Lightly lubricate the new impeller and housing interior with a marine-safe lubricant. Install the new impeller onto the driveshaft, turning the shaft in its normal rotational direction to bend the vanes correctly.
8. Reassemble Pump: Install the new gasket and wear plate, then secure the water pump housing.
9. Reattach Lower Unit: Reinstall the lower unit, ensuring the driveshaft, water tube, and shift shaft are correctly aligned. Torque bolts to manufacturer specifications.
10. Refill and Test: Refill the gearcase with fresh lubricant. Reconnect the battery. Start the engine using a flush-muff on a water hose and check for a strong, steady stream from the tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this impeller fits my specific engine?

A: The best way to ensure compatibility is to verify your engine's model, horsepower, and year against the "Compatible Engine Models" table. Pay close attention to any serial number ranges listed. For Mercury/Mariner owners, our Mercury Serial Number Guide can help you locate this information on your engine.

Q: What are the symptoms of a worn or failed water pump impeller?

A: The most common sign of a failing impeller is engine overheating, often indicated by a warning alarm or gauge. Other symptoms include a weak or non-existent water stream from the "tell-tale" outlet, or finding brittle, cracked, or broken blades during a visual inspection.

Q: How often should I replace my water pump impeller?

A: As a general maintenance rule, it's recommended to inspect your impeller annually and replace it every 1-2 years or every 100-200 hours of engine use. Replacement intervals should be shorter if you operate primarily in saltwater or sandy/silty 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.