Mercury – 300 Hour Maintenance Kit | FourStroke EFI Service | Complete OEM Components | 8M0113483

Overview

Any boater who puts real time on the water knows that a well-serviced engine changes everything. There’s a certain ease that settles in when you’ve taken care of your outboard — the throttle responds cleaner, the idle evens out, and your mind relaxes because you know the machine beneath you is ready for the next stretch of open water. The Mercury 8M0113483 300 Hour Maintenance Kit brings that kind of confidence back into your routine. It’s the sort of kit you keep on hand because you want your engine to feel as dependable on hour 300 as it did on hour three.

Key Features

• Complete 300-hour service kit for Mercury 4-cylinder 40–60 horsepower FourStroke EFI outboards
• Designed for engines with standard gearcases, serial number 1C000001 and higher
• Includes oil filter, low-pressure and high-pressure fuel filters, oil drain seal, gearcase seals, thermostat and gaskets, four spark plugs, water pump impeller kit, and anode set
• Premium filtration components built with high pleat counts and corrosion-resistant housings
• Components match Mercury Marine original equipment standards for precision and longevity

Engine & Boat Compatibility

• Fits Mercury 4-cylinder FourStroke EFI outboards from 40 to 60 horsepower
• Compatible with standard gearcase models (serial 1C000001 and above)
• Common on fishing boats, pontoons, runabouts, utility skiffs, and small offshore hulls
• Ideal for owners who log substantial seasonal hours or operate in demanding environments

Performance & Practical Benefits

A full 300-hour service is more than just a checklist — it’s what keeps your engine running tight, smooth, and steady when you need it most. This kit brings together every high-wear and high-importance part in one place, saving you from parts-chasing or mismatched components. You’ll feel the benefit right away: cleaner starts, sharper throttle response, cooler running, and far fewer surprises when you push off from the dock.

The new impeller restores strong, reliable cooling flow. Fresh spark plugs bring back crisp ignition. New filters protect your fuel system from the kind of debris that causes hesitation or rough running. And the new seals and anodes help your lower unit stay secure and corrosion-resistant, especially if you split your time between saltwater and freshwater. Each piece fits with the precision you expect from a Mercury Marine part, so installation feels straightforward rather than fussy.

Why Buy OEM

For a major service interval like this, the difference between genuine and aftermarket parts becomes very real. With OEM, you’re getting components designed specifically for your Mercury FourStroke EFI — correct dimensions, correct materials, and the confidence that everything works together exactly as the engineers intended. It’s a practical, long-view investment: far fewer complications, longer engine life, and better day-to-day performance. When you rely on your boat often, you’ll want the same reliability from the parts you put in it.

FAQ

Q1: Which engines does the Mercury 8M0113483 300 Hour Maintenance Kit fit?

It fits Mercury 4-cylinder 40–60 horsepower FourStroke EFI outboards with standard gearcases (serial 1C000001 and above).

Q2: How is this different from aftermarket service kits?

OEM kits use premium filtration, precise fitment, and Mercury-tested materials that hold up better over time.

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

Check your serial number and verify that your engine is a FourStroke EFI model within the 40–60 horsepower range.

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

Yes — all components are designed for durability in any environment.

Q5: Is the installation manageable for most boat owners?

If you’re comfortable doing routine maintenance, you’ll find the process straightforward with common tools