Water Pump Impeller Kit – Fits Mercury/Mariner/Force 25-50 HP (Replaces 821354A2, 821354A1)

Water Pump Impeller Kit – Fits Mercury/Mariner/Force 25-50 HP (Replaces 821354A2, 821354A1)

This water pump impeller repair kit is designed for Mercury/Mariner 25-50 HP 4-stroke outboards (1998 and newer, 2 & 3 cylinder models) and Force 40-50 HP outboards (1995–1997). It provides a reliable solution for maintaining your engine’s cooling system.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 821354A2, 821354A1, 821354A04; Sierra 18-4531; GLM 12045; and Recmar REC821354A2.

• Includes a high-quality neoprene impeller, stainless steel wear plate, and all necessary gaskets and seals for a complete overhaul.
• Engineered for use in both fresh and salt water environments.
• Installed in the lower unit of the outboard motor.

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

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (47-85089-10)
• 1 x Drive Key (85119)
• 1 x Wear Plate (8213542)
• 1 x Gasket Upper (27-822189)
• 1 x Gasket Lower (27-822217)
• 1 x Tube Seal Short (43023)
• 1 x Tube Seal Long (823547-1)
• 2 x Washer (12-86645)

Installation Guide

1. Safety First: Disconnect the battery and remove the spark plug wires to prevent accidental starting.
2. Drain Gearcase Lube: Place a drain pan under the lower unit and remove the upper and lower drain screws to drain the gear oil.
3. Remove Lower Unit: Unbolt the lower unit (gearcase) from the upper leg of the outboard. This may require an assistant.
4. Access Water Pump: With the lower unit removed, locate and unbolt the water pump housing, typically secured with four bolts.
5. Inspect and Remove Old Parts: Slide the housing up the driveshaft. Remove the old impeller, wear plate, gaskets, and seals. Clean all mating surfaces thoroughly.
6. Install New Components: Lightly grease the new wear plate and install it. Slide the new impeller onto the driveshaft, ensuring the fins are oriented correctly (typically clockwise).
7. Reassemble Pump Housing: Install the new gaskets and seals. Carefully lower the housing over the impeller, rotating the driveshaft to align the fins. Secure the housing bolts.
8. Reinstall Lower Unit: Guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align correctly. Fasten the bolts to the manufacturer's torque specifications.
9. Refill Gearcase: Fill the gearcase with fresh marine gear lube from the bottom hole until it flows out the top hole, then replace both screws.
10. Test Operation: Reconnect the battery and spark plug wires. Start the engine in water and verify a steady stream of water is exiting the tell-tale port.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my engine?

A: The most reliable method is to match your engine's serial number to the ranges listed in the compatibility table. The serial number is usually found on a tag on the transom bracket. If you are unsure, use the Mercury Serial Number Guide linked above or consult a professional.

Q: What are the common signs of a failing water pump impeller?

A: The most common symptom is engine overheating, often triggered by an alarm. You may also notice a weak or non-existent water stream from the "tell-tale" outlet port, even at idle.

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

A: For preventative maintenance, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of use, depending on operating conditions (e.g., saltwater vs. freshwater, sandy/silty water).

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.