Water Pump Impeller Kit – Fits Mercury/Force 25-50 HP Outboard Motors (Replaces 47-8508910, 47-850893, 47-8M0027792)

Water Pump Impeller Kit – Fits Mercury/Force 25-50 HP Outboard Motors

This water pump impeller kit is designed for a wide range of Mercury Marine, Mariner, Chrysler, and Force 25-50 HP, 2-stroke and 4-stroke outboard motors, covering models from 1994 to 2014. It serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring reliable performance for your engine's cooling system.

Engineered to meet or exceed original equipment specifications, this kit provides an essential solution for routine maintenance or addressing cooling issues like engine overheating or a weak water stream from the tell-tale.

• Installation Type: Direct Replacement
• Material: Durable neoprene rubber impeller with a corrosion-resistant metal alloy hub.
• Key Component Included: Kit comes with the necessary impeller and drive key for a complete installation.

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 Outboards

Force/Chrysler Outboards

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (Replaces 47-8508910)
• 1 x Impeller Key (Replaces 28-85119)

Installation Guide

Professional installation is recommended. The following are general steps; always refer to your specific service manual.

1. Safety First: Disconnect the battery and remove the spark plug wires.
2. Access the Lower Unit: Shift the outboard into neutral and remove the bolts securing the lower unit (gearcase) to the upper driveshaft housing. Carefully separate the two halves.
3. Open the Water Pump: Locate and unbolt the water pump housing, which sits on top of the lower unit.
4. Remove Old Impeller: Slide the housing off to expose the impeller. Note the direction of the vanes, then remove the old impeller and the impeller key from the driveshaft.
5. Clean and Inspect: Clean the inside of the housing and the wear plate. Inspect them for deep grooves, warping, or corrosion and replace if necessary.
6. Install New Impeller: Lightly lubricate the new impeller and housing interior with marine grease. Place the new key in its slot on the driveshaft and slide the new impeller on, turning the shaft clockwise to bend the vanes into place.
7. Reassemble: Install new gaskets and re-secure the water pump housing, torquing bolts to the manufacturer's specification.
8. Reattach Lower Unit: Carefully guide the lower unit back into position, ensuring the driveshaft, shift shaft, and water tube align correctly. Secure the bolts.
9. Test Operation: Reconnect the battery and start the engine in a test tank or with a water flusher. Confirm a strong, steady stream of water is exiting the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this impeller fits my specific engine?
The most reliable method is to match your engine's serial number to the ranges listed in the compatibility tables above. If you only have the model and year, ensure it is listed and does not have a specific serial number requirement that excludes it.

What are the signs of a failing impeller?
Common symptoms include the engine running hotter than normal, an intermittent or weak water stream from the "tell-tale" outlet, and in severe cases, an engine overheating alarm. The rubber can become brittle and cracked over time, reducing its pumping efficiency.

How often should I replace the water pump impeller?
For preventative maintenance, it is recommended to replace your impeller every 1-2 years or every 100-200 hours of operation, whichever comes first. This interval can vary based on usage conditions (e.g., saltwater vs. freshwater, sandy/silty water).

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.