Protect your Mercury investment with genuine OEM parts that last. This LOCKWASHER, (M6) delivers years of reliable service – not just one season like cheap alternatives.

Engineered to Mercury’s rigorous OEM standards, this component ensures reliable operation across all engine RPM ranges. Part number 400256 is manufactured to exact Mercury Marine factory specifications for precision installation and optimal performance. Constructed from premium marine-grade materials designed to withstand harsh saltwater and freshwater environments.

Factory parts exist for a reason — they work. Part 400256 undergoes rigorous Mercury Marine quality testing that aftermarket manufacturers skip. The result? Reliable performance season after season.

Compatible Mercury Marine Engines

FITS: 10-115HP MARINER, MERCURY (MAGNUM, MARATHON, SEA PRO)

• Fits MARINER, MERCURY 10-115HP engines
• Compatible HP: 10HP, 100HP, 110HP, 115HP
• Model types: MAGNUM, MARATHON, SEA PRO
• Covers 24 serial number ranges
• Configurations: Jet Drive, Outboard
• OEM genuine Mercury Marine part

COMPLETE SERIAL NUMBER COMPATIBILITY:

10HP Models

• 10HP MAGNUM (Mariner): 0D038000-0D279999, 9596000-9792199
• 10HP MARATHON (Mariner): 0D038000-0D279999, 9596000-9792199
• 10HP OUTBOARD (Mercury)
• 10HP SEA PRO (Mercury): 0D038000-0D279999, 9596000-9792199

100HP Models

• 100HP OUTBOARD (Mariner): 0A722297-0D283221, 0D283222-0G760299, 9523034-9793576, 9793577-0P016999
• 100HP OUTBOARD (Mercury): 0B209468-0D283221, 0D283222-0G760299, 9523034-9793576, 9793577-0P016999

110HP Models

• 110HP JET (Mercury)

115HP Models

• 115HP OUTBOARD (Mariner): 0C100000-0D283221, 0D283222-0G760299, 9559771-9793576, 9793577-0P016999
• 115HP OUTBOARD (Mercury): 0C100000-0D283221, 0D283222-0G760299, 9559771-9793576, 9793577-0P016999

Not sure where to find your engine’s serial number? View our quick reference guide to locate it on your Mercury Marine engine.

Verification & Support

Questions about part 400256? Use our parts finder tool to verify fitment yourself. Prefer to talk to an expert? Use the contact buttons at the bottom of this page to reach our team by text, call, or email

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