Water Pump Repair Kit – Fits Mercury/Mariner 25-50HP Outboards (Replaces 821354A2)

Water Pump Repair Kit – Fits Mercury/Mariner 25-50HP Outboards (Replaces 821354A2)

This comprehensive water pump repair kit is designed for Mercury and Mariner outboards ranging from 25 to 50 HP, covering both 2-stroke and 4-stroke models manufactured between 1994 and 2018. It is also compatible with select Force 40HP and 50HP outboards from 1995–1997.

This kit is a direct replacement for Mercury/Mariner part number 821354A2 (which supersedes 821354A1 and 821354A04) and aftermarket parts from Sierra (18-4531), GLM (12045), Pro Marine (3219/3219-1), and SEI Marine (96-265-03BK).

• Installation Method: Direct OEM Replacement
• Core Components: Includes a durable neoprene rubber impeller and a 316 stainless steel wear plate.
• Broad Compatibility: Fits a wide range of 2-cylinder, 3-cylinder, and 4-stroke Mercury, Mariner, and Force engines.

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 Outboard Applications

Force Outboard Applications

Technical Specifications

Package Contents

• 1 × Water Pump Impeller (89640)
• 1 × Face Plate/Wear Plate (12505 821354-2)
• 2 × Water Tube Seal (85180 43023/85181 823547-1)
• 2 × Washer (31175 12-86645-1)
• 2 × Gasket (37490 27-822189/37700 27-822217)

Explosion Diagram

Installation Guide

1. Safety First: Disconnect the battery and remove the spark plug wires before beginning work.
2. Access the Lower Unit: Drain the gearcase oil. Remove the bolts securing the lower unit (gearcase) to the engine's midsection and carefully lower it.
3. Remove Old Pump: Unscrew the bolts holding the water pump housing in place. Slide the housing and old impeller off the driveshaft.
4. Clean and Inspect: Clean the mounting surfaces thoroughly. Inspect the driveshaft for any scoring or damage.
5. Install New Components: Lightly grease the new wear plate and gaskets. Slide the new impeller onto the driveshaft, ensuring the fins are oriented correctly (typically clockwise rotation).
6. Reassemble Pump: Place the new gaskets and housing over the impeller. Tighten the housing bolts to the manufacturer's specified torque.
7. Reinstall Lower Unit: Guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align correctly. Secure with bolts and refill the gearcase oil.
8. Test Operation: Reconnect the battery and start the engine using a water source (flushing muffs). Check for a strong, steady stream from the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this fits my engine?
First, check the compatibility tables above and match your engine's brand, model, horsepower, and year range. For Mercury and Force models, it is critical to also verify your engine's serial number against the ranges listed. If you need help finding your serial number, please consult our Mercury Serial Number Guide.

What are the common signs of a failing water pump?
The most common symptoms are a weak or non-existent water stream from the "tell-tale" outlet and an engine temperature alarm or overheating. You should stop the engine immediately if it overheats to prevent serious damage.

How often should I replace the water pump impeller?
For preventative maintenance, it is recommended to replace the impeller every 1-2 years or every 100-200 hours of use. This interval can be shorter if you frequently operate in sandy, silty, or saltwater conditions.

OEM vs. Aftermarket?
This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials such as neoprene rubber and 316 stainless steel. 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.