Mercury – Heavy Duty Sea Water Pump Impeller Repair Kit | MerCruiser 4.5L & 6.2L | Composite & Elastomer | 8M0137221

Overview

When you spend enough days on the water, you learn to appreciate parts that simply do their job without a fuss. That steady reliability becomes part of the boating experience—one less thing to worry about when you’re watching the horizon or drifting into your favorite cove. The Mercury 8M0137221 Heavy Duty Sea Water Pump Impeller Repair Kit is one of those behind-the-scenes components that keeps your engine cool, calm, and running exactly as it should. You install it once, feel the difference immediately, and forget about it until the next service interval rolls around. That kind of peace of mind is worth its weight in gold when you’re far from the dock.

Key Features

• Four-piece heavy duty water pump impeller repair kit
• Includes replacement impeller, over-molded front wear plate, rear wear plate, and housing gasket
• Designed for consistent cooling flow and higher water volume
• Durable elastomer impeller maintains flexibility across wide temperature ranges
• Engineered to Mercury Marine OEM specifications for MerCruiser engines

Engine & Boat Compatibility

• Fits 4.5L MerCruiser V6 engines (serial number 2A531163 and above)
• Fits 6.2L MerCruiser V8 engines in sterndrive and inboard configurations within the listed serial ranges
• Compatible with select TowSport inboard engines
• Ideal for runabouts, sport cruisers, tow boats, and performance-focused sterndrive setups

Performance & Practical Benefits

A good cooling system doesn’t just protect the engine—it changes how the whole boat feels. With the 8M0137221 kit installed, water moves through the pump with a smooth, steady flow that keeps operating temperatures consistent. You won’t feel that nervous hesitation when you throttle up, and you won’t be peeking at the temperature gauge every few minutes.

The upgraded wear plates are built to hold up against sand, silt, and the occasional debris that slips through raw-water intakes. The impeller itself has a strong, flexible feel that resists cracking after long, hot days on the water. Put together, the parts fit cleanly, seal properly, and restore the pump’s efficiency so your engine can run the way it was designed to.

This is the kind of upgrade that makes each ride feel smoother—tight response, predictable cooling, no surprises.

Why Buy OEM

When you’re maintaining a MerCruiser engine, cutting corners almost always costs more in the long run. An OEM Mercury Marine part is designed to match the exact dimensions and material requirements of the pump it’s going into. That means no forced fit, no questionable quality, and no early failures that catch you off guard.

You’re not just buying a replacement part—you’re buying the confidence that comes with equipment engineered, tested, and proven by Mercury. With OEM components, you get better longevity, easier installation, and performance you can trust during the entire boating season. It’s practical, it’s reliable, and it’s the smart choice for any boater who takes their time on the water seriously.

FAQ

Q1: Which engines does this impeller kit fit?

It fits select 4.5L and 6.2L MerCruiser V6 and V8 engines within the newer serial number ranges.

Q2: What sets this kit apart from aftermarket versions?

Mercury’s material quality, precise engineering, and proven durability outperform generic alternatives.

Q3: How can I confirm compatibility?

Check your engine’s serial number and compare it to the ranges listed in your owner’s manual or service guide.

Q4: Can this be used in saltwater?

Yes—its materials are designed for harsh marine environments, both freshwater and saltwater.

Q5: Is installation simple?

Most experienced DIY boaters can install it, and professional shops can complete it quickly.