Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-8508910)

Water Pump Impeller – Fits Mercury/Mariner 15-50 HP (Replaces 47-8508910)

This water pump impeller is a direct replacement for a wide range of Mercury/Mariner outboard engines from 15 to 50 HP (2-Stroke & 4-Stroke) and Force outboards from 25 to 50 HP. It's engineered to meet or exceed original equipment specifications for reliable cooling performance.

Replaces Mercury Part Numbers: 47-8508910, 47-850893, 47-850891, 47-8508920, 47-8M0024502, 47-8M0027792, 47-8M0204712. Also replaces aftermarket part numbers: Sierra 18-3057, Mallory 9-45303, GLM 89640, and CEF 500315.

• Engineered for direct, hassle-free installation.
• Constructed from a durable neoprene/rubber compound for longevity.
• Complete kit includes impeller, key, gasket, and washers for a full service.

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.

Mercury/Mariner

Force/Chrysler

Technical Specifications

Package Contents

This kit includes the following components for a complete water pump service. Note: Package contents are based on common aftermarket kits and may differ slightly from OEM packages.

• 1 x Water Pump Impeller (Replaces 47-8508910)
• 1 x Key (Replaces 28-8M0032828)
• 1 x Gasket (Replaces 27-822189)
• 2 x Washers (Replaces 12-866451)

Explosion Diagram

Installation Guide

1. Disconnect the negative battery cable for safety.
2. Place a drain pan under the lower unit and remove the gear lube drain screw to empty the oil.
3. Unbolt and carefully slide the lower unit off the drive shaft housing.
4. Remove the bolts securing the water pump housing and lift it off.
5. Take note of the vane direction on the old impeller before removing it, along with the key and old gaskets.
6. Thoroughly clean the mounting surfaces of any old gasket material or debris.
7. Install the new gasket and wear plate onto the lower unit.
8. Slide the new impeller key into the driveshaft slot.
9. Lubricate the new impeller with a marine-safe lubricant and slide it onto the driveshaft, turning it in the direction of engine rotation to bend the vanes correctly.
10. Reinstall the water pump housing and tighten the bolts to the manufacturer's specified torque.
11. Carefully guide the lower unit back into place, ensuring all shafts align, and secure it. Refill with fresh gear lube.
12. Reconnect the battery, supply the engine with cooling water, and test run to check for proper water circulation.

Troubleshooting & FAQ

How do I confirm this impeller fits my engine?

First, check your engine's model, horsepower, and year against our "Compatible Engine Models" table. For Mercury owners, use the linked serial number guide for precise identification. Finally, ensure your existing part number is listed in our "Part Number Cross-Reference" table.

What are the signs of a bad water pump impeller?

Common symptoms include the engine overheating, a weak or absent water stream from the "telltale" outlet, and the impeller being visibly cracked, brittle, or having broken vanes upon inspection.

How often should I replace the impeller?

As a key part of preventative maintenance, we recommend inspecting the impeller annually and replacing it every 1-2 years or 100-200 hours of operation, whichever comes first. More frequent replacement may be necessary in saltwater or high-debris environments.

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.