Mercury – 300 Hour Maintenance Kit | MerCruiser 4.5L MPI Alpha Series | OEM Service Components | 8M0147066

Overview

When you run a MerCruiser 4.5L MPI engine, you get used to a certain confidence—the kind that settles in when the engine fires instantly, idles without drama, and pushes your boat onto plane with smooth, even strength. But even the most reliable engines deserve a real reset every few hundred hours. The Mercury 8M0147066 300 Hour Maintenance Kit gives you that peace of mind in one straightforward package. It’s built for boaters who don’t want surprises, just dependable performance whether they’re cruising wide water or easing back into a familiar slip at sunset.

Key Features

• Complete 300-hour service kit for 4.5L MPI Alpha sterndrive engines
• Includes oil filter, fuel filter, spark plugs, thermostat, thermostat gasket, serpentine belt, gearcase drain seals, and PCV valve
• High-pleat filtration components for strong contaminant control
• Marine-grade materials and electroplated housings for corrosion resistance
• All parts engineered to meet Mercury Marine OEM standards

Engine & Boat Compatibility

• Fits MerCruiser 4.5L MPI engines paired with Alpha sterndrives
• Designed for model years 2014 and newer
• Perfect for bowriders, sport boats, family runabouts, and fishing vessels powered by Mercury’s modern 4.5L platform

Performance & Practical Benefits

A 300-hour service is more than a tune-up—it’s a reset for nearly every system that keeps your 4.5L MPI running tight and dependable. This kit brings better throttle response, cleaner fuel delivery, steadier idle, and stronger cooling efficiency back into your engine’s daily rhythm.

Fresh spark plugs restore crisp ignition. The PCV valve helps maintain clean, predictable combustion. The serpentine belt ensures that accessories spin smoothly without squeal or hesitation. And the updated thermostat set keeps engine temperatures stable—something you’ll appreciate during long idle periods or hot-weather cruising.

The filtration components are the unsung heroes of this kit. With premium pleat counts and durable housings, the oil and fuel filters clean far more efficiently than generic replacements. Over time, that means less internal wear, steadier performance, and fewer issues caused by water or debris sneaking into your system.

Together, these parts reinforce the strength and reliability of Mercury’s 4.5L MPI design. Every component fits exactly as the old one came off, giving you a service that feels secure, predictable, and refreshingly straightforward.

Why Buy OEM

Aftermarket parts may seem convenient, but they rarely match the build quality, filtration efficiency, or long-term durability of genuine Mercury components. With OEM, you know every piece is engineered specifically for your 4.5L MPI engine—no tolerance issues, no questionable materials, no unexpected failures. It’s the smart choice for boaters who want fewer problems and more weekends spent on the water.

FAQ

Q1: Which engines does this kit fit?

It fits MerCruiser 4.5L MPI engines with Alpha sterndrives, 2014 and newer.

Q2: What sets this apart from aftermarket kits?

Precision fit, premium filtration, and the proven reliability of Mercury Marine engineering.

Q3: How do I confirm it’s right for my boat?

If your engine is a 4.5L MPI paired with an Alpha sterndrive, this is the correct 300-hour kit.

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

Definitely. All components are corrosion-resistant and designed for harsh marine environments.

Q5: Is installation manageable for most boat owners?

Yes—if you’re comfortable with routine maintenance, this kit installs cleanly with basic tools.