Mercury – Water Pump Repair Kit | Four-Stroke Cooling System | Marine-Grade Components | 8M0205803

Overview

Any boater who's spent long days offshore or lazy evenings drifting near the inlet knows how much trust we put into our engines. That steady hum, the smooth throttle response, the confidence that the temperature needle will stay right where it should — all of it depends on a healthy water pump. When that system is working right, you barely think about it. But when it falters, you feel it instantly. The Mercury Marine part 8M0205803 Water Pump Repair Kit brings back that sense of certainty. It gives you everything you need to restore the cooling system your four-stroke relies on, keeping your engine running cool, steady, and ready for whatever water lies ahead.

Key Features

• Complete water pump repair kit for Mercury one-hundred-seventy-five to three-hundred horsepower four-stroke outboards
• Also fits Mercury Racing four-hundred-fifty R engines and select three-point-four liter V6 and four-point-six liter V8 platforms
• Includes impeller, impeller key, face plate, seals, O-rings, gaskets, actuator seal, drain plug seal, and face seal tool
• Designed for reliable water flow and cooling efficiency
• Mercury Marine part number 8M0205803
• Straightforward installation using common shop tools

Engine & Boat Compatibility

This kit is designed for:

• Mercury four-stroke outboards from one-hundred-seventy-five to three-hundred horsepower
• Mercury Racing four-hundred-fifty R
• Mercury V6 and V8 four-stroke models (serial number two-B-five-two-nine-four-eight-two and above)

Perfect for boats such as:

• Offshore center consoles
• Multi-engine fishing rigs
• Performance boats running high-load cycles
• Family cruisers and pontoons relying on dependable cooling

Performance & Practical Benefits

A well-functioning water pump isn’t something you admire — it’s something you feel. You feel it when your boat jumps onto plane without hesitation, when your engine stays cool during long idle stretches, and when the temperature holds steady even in warm shallow bays. This kit restores that confidence by giving you fresh components that seal tightly, move water efficiently, and stand up to the heat and strain of real-world use.

The impeller is crafted to stay flexible across wide temperature swings, keeping water flowing smoothly through the cooling passages. Fresh gaskets and seals eliminate small leaks that can rob your engine of cooling power. The face plate provides a clean, solid surface for the impeller to operate against, ensuring predictable flow and consistent pressure. Together, these parts create a cooling system that runs tight, smooth, and stable — exactly what you want beneath you when the weather changes or the run home gets long.

Why Buy OEM

Cooling components are not the place to experiment with aftermarket substitutes. Even slight differences in impeller stiffness, seal material, or plate thickness can lead to overheating, reduced flow, or premature wear. Mercury’s OEM design is engineered specifically for their four-stroke platforms, ensuring proper fit, correct clearances, and reliable long-term performance.

Choosing OEM means choosing parts that were built and tested for your engine — parts that protect your investment and keep your outboard performing exactly the way Mercury intended. It’s practical, proven, and smart boating.

FAQ

Q1: Which engines does Water Pump Repair Kit 8M0205803 fit?

It fits Mercury one-hundred-seventy-five to three-hundred horsepower four-stroke outboards, Mercury Racing four-hundred-fifty R, and select V6 and V8 engines (serial number two-B-five-two-nine-four-eight-two and up).

Q2: What makes this kit better than aftermarket options?

Every component is engineered to Mercury’s exact cooling specifications for flow, durability, and fit.

Q3: How do I confirm this is the correct kit for my engine?

Check your engine’s serial number or owner’s manual and match it to the part number listed.

Q4: Can this be used in both freshwater and saltwater?

Yes — all materials are designed to withstand corrosion, heat, and constant exposure to marine conditions.

Q5: Is installation straightforward for most boat owners?

Yes. With common tools and basic mechanical familiarity, most owners can complete the repair confidently.