Water Pump Impeller Service Kit – Fits Mercury/Mariner 13.5-25 HP Outboards (Replaces 47-8508910, 47-850893, 47-8M0027792)

Water Pump Impeller Service Kit – Fits Mercury/Mariner 13.5-25 HP Outboards (Replaces 47-8508910, 47-850893, 47-8M0027792)

This water pump impeller service kit is designed for Mercury/Mariner 4-Stroke 13.5, 15, 18, and 25 HP outboards (1984–2005) and Mercury/Mariner 2-Stroke 20, 25, 30, and 40 HP outboards (1996–1999). It also fits select Force/Chrysler models.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring a precise fit and reliable performance for your marine engine's cooling system.

• Installation Method: Direct OEM replacement that fits the original housing without modifications.
• Impeller Material: Constructed from durable neoprene rubber for optimal flexibility and a long service life.
• Complete Kit: Includes the impeller, key, seals, O-ring, and gasket for a comprehensive 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 Outboards

Force/Chrysler Outboards

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (47-8508910)
• 1 x Impeller Key (28-85119)
• 2 x Seal
• 1 x O-Ring
• 1 x Gasket

Installation Guide

Always follow your engine's service manual for detailed instructions. The general steps for replacing a water pump impeller are as follows:

1. Safety First: Disconnect the engine's battery and remove the propeller before starting work.
2. Access the Lower Unit: Drain the gearcase lubricant and remove the lower unit (gearcase) from the outboard's driveshaft housing.
3. Remove the Water Pump Housing: Locate the water pump assembly on the lower unit. Unbolt and carefully lift the housing off. It may be tight.
4. Inspect and Remove Old Parts: Take note of the old impeller's orientation. Remove the old impeller, gaskets, wear plate, and seals from the housing.
5. Clean and Prepare: Thoroughly clean all surfaces of the pump housing and base, removing any old gasket material or debris.
6. Install New Components: Lightly lubricate the new seals and O-rings. Install the new gasket, wear plate, and impeller key.
7. Install the New Impeller: Lubricate the inside of the pump housing and the new impeller. Slide the impeller onto the driveshaft, turning the shaft clockwise to bend the vanes in the correct direction.
8. Reassemble: Reinstall the water pump housing and tighten the bolts to the manufacturer's specified torque.
9. Reinstall Lower Unit: Re-attach the lower unit to the outboard and refill the gearcase with fresh lubricant.
10. Test Operation: Reconnect the battery, start the engine using a water supply (flushing muffs), and confirm that water is exiting the "telltale" outlet.

Troubleshooting & FAQ

Q: How do I confirm this impeller kit fits my specific engine model?
A: The most reliable method is to match your engine's model, year, and serial number (if applicable) against the compatibility tables on this page. For Force applications, be sure to verify your engine's serial number falls within the specified range. When in doubt, compare the product photos and dimensions with your old part.

Q: What are the common signs that a water pump impeller needs to be replaced?
A: The most common symptoms of a worn or failed impeller include the engine overheating at idle or low speeds, a weak or non-existent stream of water from the tell-tale outlet, or a high-temperature alarm sounding from your control panel.

Q: How often should I replace the water pump impeller?
A: As a general rule of preventative maintenance, we recommend replacing your impeller every 100-200 operating hours or at least once a year, regardless of hours used. This is especially important if you operate in saltwater or water with heavy sediment.

Q: Is this an OEM 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.