Mercury – Serpentine Belt | Engine Drive System | Rubber Composite | 865615Q02

Overview

When you’re running a boat that carries the weight and grunt of an 8.1S or 496 Magnum engine, you can feel every part doing its job—especially the serpentine belt. It’s one of those pieces you rarely think about when everything’s working right, but you absolutely notice when it isn’t. That’s why having a reliable, factory-matched belt gives you a level of comfort you can’t put a price on. Whether you’re cruising a long stretch of open water or easing into a tight marina slip, this Mercury Marine part keeps your engine systems moving in smooth, steady rhythm.

Key Features

• Designed for MerCruiser 8.1S engines (2001–2004) and 496 Magnum engines (2001–2005)
• Built from a durable marine-grade rubber composite
• Measures 2,285mm for exact factory-matched fit
• Ideal for engines where the power steering pump has been removed
• Matches the original belt installed by MerCruiser
• Engineered to maintain proper tension, clean pulley engagement, and long service life

Engine & Boat Compatibility

• Fits MerCruiser 8.1S engines from serial numbers 0M025000–0W389999
• Fits MerCruiser 496 Magnum engines from serial numbers 0M025000–0W389999
• Works on engines configured without a power steering pump
• Common on performance cruisers, offshore boats, tow boats, and larger multi-purpose vessels
• Suitable for both sterndrive and inboard layouts using this accessory setup

Performance & Practical Benefits

There’s a certain feel you get when your belt is properly matched—accessories spin smoothly, electrical output stays stable, and cooling stays predictable. This belt delivers that reliable steadiness. It grabs confidently without slipping, tracks cleanly on the pulleys, and keeps all driven systems operating in sync. You’ll notice fewer squeals, fewer fluctuations under load, and a more balanced feel across the entire engine.

Because the belt length and groove pattern are identical to the original, installation is trouble-free. It slips into place with the correct natural tension, avoiding the overstretch or slack that sometimes comes with aftermarket belts. Once installed, the engine settles into a tight, precise rhythm that simply feels right.

Its marine-formulated construction is built to tolerate long days of heat, moisture, and vibration—meaning fewer replacements and less maintenance overall. On a high-output engine like the 8.1S or 496 Magnum, that durability pays off every time you turn the key.

Why Buy OEM

When it comes to belts, proper fit isn’t a luxury—it’s a necessity. An OEM part ensures you’re getting the exact material quality, groove depth, and length required for your engine to perform the way it was designed. You won’t fight premature wear, slip, or misalignment. You also avoid the gamble of inconsistent rubber compounds found in many aftermarket options. If a fellow boater asked what to choose, you’d recommend the OEM belt without hesitation. It’s dependable, cost-effective, and built for the long haul.

FAQ Section

Q1: Which engines does this belt fit?

It fits MerCruiser 8.1S engines (2001–2004) and 496 Magnum engines (2001–2005) within the listed serial range.

Q2: What makes it different from aftermarket belts?

It matches the original specifications exactly, ensuring proper tension, smooth engagement, and long-term durability.

Q3: How can I confirm it’s the right belt?

Check your serial number, confirm your engine model, and verify that your power steering pump has been removed.

Q4: Can it be used in both saltwater and freshwater boats?

Yes, the belt material is designed for both environments.

Q5: Is installation straightforward?

Most boaters can replace it using basic tools and the engine’s belt-routing diagram.