Water Pump Repair Kit – Fits Mercury/Mariner 25-50 HP (Replaces 821354A2, 821354A1, 821354A04)

Water Pump Repair Kit – Fits Mercury/Mariner 25-50 HP (Replaces 821354A2, 821354A1, 821354A04)

This water pump repair kit is designed for a wide range of Mercury/Mariner 25-50 HP (2-Stroke & 4-Stroke, 1998–2018) and Force 40-50 HP (2-Stroke, 1995–1997) outboard engines. It provides a reliable, direct-fit solution for maintaining your engine’s cooling system.

Engineered to meet or exceed OEM specifications, this kit serves as a direct replacement for Mercury part numbers 821354A2, 821354A1, 821354A04, and other aftermarket equivalents such as Sierra 18-4531, GLM 12045, and SEI 3219.

• Complete Repair Solution: Includes a new impeller, wear plate, gaskets, seals, and all necessary hardware for a full service.
• Durable Construction: Built with corrosion-resistant marine-grade materials to withstand harsh saltwater and freshwater environments.
• Simple Installation: Designed for a direct replacement of the water pump assembly in the lower unit, ensuring a precise fit.

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 Outboards

Technical Specifications

Package Contents

• 1 x Neoprene Impeller (Replaces 47-85089-10, 47-85089-3)
• 1 x Wear Plate (Replaces 8213542)
• 1 x Upper Gasket (27-822189)
• 1 x Lower Gasket (27-822217)
• 1 x Short Water Tube Seal (43023)
• 1 x Long Water Tube Seal (823547-1, 8235471)
• 2 x Washer (12-86645-1)
• 1 x Drive Key (85119)

Installation Guide

1. Prepare the Engine: Disconnect the battery and shift the outboard into neutral gear.
2. Drain Gearcase Oil: Place a drain pan under the lower unit and remove the drain/fill screws to drain the gearcase oil.
3. Remove Lower Unit: Loosen and remove the bolts securing the lower unit (gearcase) to the engine's midsection.
4. Separate the Unit: Carefully lower the gearcase away from the engine. You may need to disconnect the shift shaft linkage.
5. Access the Pump: With the lower unit on a workbench, unbolt and remove the water pump housing to expose the impeller.
6. Inspect Components: Take note of the old impeller vane direction. Check the housing, wear plate, and impeller for grooves, cracks, or heavy wear.
7. Remove Old Parts: Remove the old impeller, drive key, gaskets, and seals. Thoroughly clean all mating surfaces to ensure a proper seal.
8. Install New Gasket & Plate: Place the new lower gasket and wear plate onto the gearcase.
9. Install New Impeller: Insert the new drive key into the driveshaft. Slide the new impeller onto the shaft while rotating it clockwise to correctly orient the vanes.
10. Reinstall Housing: Fit the new upper gasket and carefully place the water pump housing over the impeller. Secure it with the bolts, tightening them to the manufacturer's specified torque.
11. Reassemble & Refill: Reattach the lower unit to the engine, reconnecting the shift shaft. Refill the gearcase with fresh marine gear oil.
12. Test Operation: Start the engine using a water supply (flushing muffs) and confirm a steady stream of water is exiting the tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my specific engine model?
A: The best way is to check the compatibility tables provided on this page. Cross-reference your engine's make, model, year, and especially the serial number range noted in the "Notes" column. If your engine is listed, the kit is a confirmed fit.

Q: What are the signs that my water pump needs to be replaced?
A: Common symptoms of a failing water pump include a weak or no water stream from the "tell-tale" outlet, the engine overheating at idle or low speeds, or a high-temperature alarm sounding. Visually, a worn impeller will have cracked, brittle, or permanently curved vanes.

Q: How often should I replace my water pump impeller?
A: For preventative maintenance, it is highly recommended to replace your impeller every 1-2 years or every 100-200 hours of operation, whichever comes first. This interval can be shorter if you frequently operate in sandy, silty, or saltwater conditions.

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.