QUICKMARINER Outboard Water Pump Impeller Kit Mercury 25-50 HP, Rubber Impeller with Housing and Seals

QUICKMARINER 821354A2 is a complete aftermarket water pump impeller kit designed to restore cooling performance on Mercury Marine 25–50 HP outboards.

When an outboard motor runs hot or shows reduced water flow, the impeller and its surrounding components are often the cause. This QUICKMARINER kit provides the key replacement parts compatible with Mercury Marine lower unit gearcases—covering many 25, 30, 40 and 50 HP models—to help you get back on the water quickly. The set includes the rubber impeller plus the upper housing and seals, making it suitable as a service repair or a dependable spare for routine maintenance.

Which Mercury outboards will this kit fit?

This kit is engineered to match common Mercury Marine lower unit configurations for 25, 30, 40 and 50 HP outboard engines. It replaces OEM reference numbers and is cross-compatible with well-known aftermarket equivalents.

• Fits Mercury Marine 25, 30, 40, 50 HP lower unit gearcase models
• Compatible with Mercury part numbers 821354A2, 46-821354A2 and 821354A1
• Direct replacement for Sierra Marine 18-4531
• Intended for the specified horsepower range—verify your lower unit manual for exact fit

What components are included and why they matter?

The kit groups the wear parts you typically replace during a water pump service, eliminating the need to source each item separately. Replacing worn parts together ensures a better seal and consistent water flow, reducing the chance of repeat disassembly.

• Rubber impeller: the rotating element that moves cooling water through the engine
• Housing assembly (upper): secures the impeller and maintains proper alignment
• Water tube seal and gasket: prevent leaks and preserve pressure in the cooling circuit
• Washer, wear plate and drive key: small parts that keep the impeller indexed and protect metal surfaces

How do I use this kit during maintenance?

Replacing the water pump is a standard lower-unit service for outboards. Remove the lower unit according to your engine manual, inspect components, swap the worn impeller and seals for the new parts in this kit, and reassemble following torque and alignment specifications.

• Drain and support engine before lowering the gearcase—follow safety practices
• Remove old impeller, inspect housing bore and drive shaft for corrosion or scoring
• Install new impeller and wear plate, replace gaskets and seals, and reassemble housing
• Test water flow at idle before launching to verify correct installation

Is this an OEM part or an aftermarket alternative?

This QUICKMARINER kit is an aftermarket service assembly designed as a reliable backup or replacement for original parts. It matches key fit and function references to work with Mercury lower units while offering a cost-effective option for upkeep.

• Aftermarket kit built to fit specified Mercury part numbers
• Useful as a service spare for boating season preparedness
• Includes all typical replacement pieces to avoid multiple orders

Who is this for: Boaters, marine technicians, and do-it-yourself owners who run Mercury 25–50 HP outboards and want a complete, ready-to-install water pump service kit. It’s ideal for routine maintenance, seasonal rebuilds, or carrying as a spare on extended trips. Always confirm the exact part number for your lower unit before ordering and consult your engine’s service manual for installation guidance.