8-9.9hp FourStroke 300 Hour Maintenance Kit

Mercury Marine 8-9.9hp FourStroke 300 Hour Maintenance Kit

The Mercury Precision Parts 300 Hour Maintenance Kit (part number 8M0120837) provides everything required to perform a thorough 300-hour service on Mercury 8 HP and 9.9 HP FourStroke carbureted outboards equipped with standard gearcases, covering engines with serial numbers 0R042475 and above. Engineered and produced by Mercury Marine to stringent original equipment manufacturer specifications, this all-in-one kit is designed to maximize the performance and reliability of your Mercury or Mariner outboard engine.

Purchasing a complete service kit means there is no need to individually source and order separate components — every required service replacement item arrives in one convenient package. Routine maintenance at the 300-hour interval is straightforward using common shop tools, and following the owner's manual for recommended service intervals helps keep your engine running longer and stronger while protecting your boating investment.

The kit addresses the key service systems at once: cooling system components such as the thermostat and water pump impeller support proper water flow and stable operating temperature; new spark plugs and the fuel filter support clean combustion and dependable starting; gear case and oil drain seals maintain proper fluid containment; and the unit anode helps reduce galvanic corrosion in marine environments. Mercury 4-stroke engine oil and gear lube are recommended for use with this kit but are sold separately.

Key Features

• Complete selection of required 300-hour service replacement items in one box — no need to order separate parts
• Compatible with Mercury 8 HP and 9.9 HP FourStroke carbureted outboards with standard gearcases, serial numbers 0R042475 and above
• Includes fuel filter, oil drain seal, gear case drain seals, thermostat, thermostat gasket, 2 spark plugs, water pump impeller kit, and unit anode
• Produced by Mercury Marine to stringent OEM specifications to maximize performance of Mercury and Mariner outboards
• Periodic maintenance is easy to perform using common shop tools
• Cooling system refresh: thermostat and impeller service helps support proper water flow and stable operating temperature
• Corrosion protection: includes an anode to help reduce galvanic corrosion in marine environments
• Note: Mercury 4-stroke engine oil and gear lube are sold separately