Quicksilver Water Pump Repair Kit 821354A2 for Mercury/Mariner 25–50hp — Complete Impeller & Seal Kit

Quicksilver 821354A2 is a complete water pump repair kit designed to restore cooling performance for select Mercury and Mariner 25–50hp outboard engines.

This kit gathers the essential replacement parts you need to service the water pump on compatible 2‑stroke and 4‑stroke outboards. Built to the specifications expected from Quicksilver — the original-equipment supplier for Mercury Marine — the kit simplifies a common maintenance job so you can get your engine back to reliable cooling without guessing which parts fit.

Which outboards will this repair kit work with?

This kit is intended for specified Mercury and Mariner outboards in the 25–50 horsepower range for both 2‑stroke and 4‑stroke models. Always verify the engine year and model against your owner's or service manual to confirm compatibility before purchasing. Using the correct kit avoids fitment problems and ensures the pump components function together as designed.

• Fits select Mercury and Mariner 25–50hp outboards
• Compatible with both 2‑stroke and 4‑stroke configurations when specified
• Confirm fit by checking engine model/year in your manual

What parts are included and why do they matter?

The 821354A2 kit bundles the common wear items that determine water pump effectiveness: the impeller, drive key, face plate, gaskets, and the water tube seal. Replacing these components together restores proper water flow and sealing, reducing the risk of overheating or seal failure. Installing all supplied parts helps maintain correct clearances and alignment inside the pump housing.

• New impeller — restores rotor action for consistent cooling flow
• Drive key — secures impeller to the shaft for reliable power transfer
• Face plate and gaskets — ensure correct pump chamber sealing and pressure
• Water tube seal — prevents external leaks at the outlet connection

How difficult is the replacement and what tools are needed?

Replacing a water pump is a routine service for most mechanically inclined boat owners but does require basic tools and attention to torque and alignment. If you follow the engine’s service manual steps, the job is typically straightforward; however, limited space on some lower units can make access fiddly. If uncertain, a certified marine mechanic will complete the swap quickly and verify cooling system integrity.

• Common hand tools: socket set, screwdrivers, pliers
• Torque wrench to meet manufacturer fastener specs
• Service manual recommended for step-by-step guidance and torque values

How will replacing the pump parts affect engine performance?

Installing fresh pump components helps reestablish correct water circulation through the engine, reducing the chance of overheating and improving long-term engine reliability. While it won’t increase power, consistent cooling preserves engine life and prevents heat-related damage. Regular maintenance with OEM parts helps keep factory tolerances and performance intact.

• Restores consistent coolant flow to prevent overheating
• Maintains factory-designed clearances for efficient pump action
• Reduces risk of leaks and related engine damage

Who is this for: The Quicksilver 821354A2 water pump repair kit is aimed at boat owners, fleet operators, and marine technicians who service Mercury or Mariner outboards in the 25–50hp class. It’s suitable for anyone doing scheduled maintenance or repairing a deteriorated pump—especially those who prefer OEM-level components for fit and longevity. If you value exact-fit replacement parts and want to follow manufacturer guidance for cooling-system upkeep, this kit provides the core components needed to complete the job correctly.