Mercury – Alternator Belt | High-Output Accessory Drive Series | Reinforced Rubber | 8M0218433

Overview

If you spend enough time on the water, you learn which parts you can trust without thinking twice—those pieces of equipment that quietly do their job while you focus on the tide, the weather and the run ahead. The Mercury Alternator Belt 8M0218433 is one of those parts. It delivers the kind of quiet reliability you only appreciate when you’ve been far from the dock and everything needs to work exactly as it should. There’s a comfort in knowing your alternator will stay spinning strong, your batteries stay charged and your engine electronics keep humming along without hesitation. That’s the peace of mind this belt provides every time you turn the key.

Key Features

• Drives the alternator for steady, reliable battery charging
• Reinforced rubber construction engineered for long service life
• Designed for high-horsepower 3.4L V6 and 4.6L V8 4-Stroke outboards
• Precise fitment ensures smooth, quiet operation
• Built to Mercury Marine’s original equipment standards

Engine & Boat Compatibility

Fits Mercury engines:

• 175–300hp 3.4L V6 FourStroke (serial number 2B529482 & up)
• 450R 4.6L V8 Mercury Racing outboards
• 4.6L V8 FourStroke models requiring part number 8M0218433

Great for boat types such as:

• Center consoles and bay boats
• Off-shore rigs and sport boats
• Multi-engine setups
• Heavy-load fishing and family boats

Performance & Practical Benefits

A good alternator belt isn’t something you notice—because when it’s working right, everything else simply stays powered. What you will notice is the smoothness of the charge cycle, the quiet rotation and the steady feel of an accessory system that’s dialed in. This belt grips tightly without slipping, runs smoothly at high rpm and handles the heat created during long days under load.

You’ll appreciate how confidently it holds up over time. Reinforced materials help prevent stretching or cracking, even when the engine spends hours idling in the shallows or running hard to the next spot offshore. It installs easily using common tools and sits perfectly aligned once tensioned. The end result is a trim, reliable and secure drive system that keeps your batteries and electronics ready for anything the day throws at you.

Why Buy OEM

With an alternator belt, the material blend and dimensions matter more than most people think. Aftermarket belts may look similar, but slight changes in width, flexibility or internal reinforcement can lead to squealing, slipping or premature wear.

A genuine Mercury Marine part number guarantees the exact construction your engine was designed around. You’re getting longevity, the right tension characteristics and a perfect match for your pulleys and accessory components. It’s the practical choice for boaters who’d rather spend their time running the water than troubleshooting electrical issues at the dock.

FAQ

Q1: Which engines does this belt fit?

It fits Mercury 175–300hp V6 FourStroke engines and the 450R 4.6L V8 Racing platform.

Q2: What makes it better than aftermarket belts?

Its reinforced construction and precise fitment meet Mercury’s engineering standards, ensuring better grip, smoother running and longer life.

Q3: How do I confirm compatibility?

Match your engine’s serial number or compare to your existing alternator belt part number.

Q4: Can it be used in saltwater and freshwater?

Absolutely. Its materials are built for demanding marine environments.

Q5: Is installation straightforward?

Yes. It installs with basic tools and standard belt-tensioning procedures.