Experiencing engine hesitation or reduced power? This authentic Mercury Marine NUT-SHEAVE SHAFT (LEFT HAND THREAD) solves the problem with factory precision – no guessing, no compromises.

Built with Mercury Marine’s precision engineering, this component ensures reliable operation across all engine RPM ranges. Part number 20166 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 20166 undergoes rigorous Mercury Marine quality testing that aftermarket manufacturers skip. The result? Reliable performance season after season.

Compatible Mercury Marine Engines

FITS: 100-200HP MERCURY

• Fits MERCURY 100-200HP engines
• Compatible HP: 100HP, 110HP, 200HP
• Covers 24 serial number ranges
• Configurations: Outboard
• OEM genuine Mercury Marine part

COMPLETE SERIAL NUMBER COMPATIBILITY:

100HP Models

• 100HP OUTBOARD (Mercury): 1290910-1499331, 1464949-1768403

110HP Models

• 110HP OUTBOARD (Mercury): 1470349-1865778, 1865779-2798056, 2798057-3263262, 3263263-3795657, 3795658-4839253, 4839254-5206549, 7027323-7111347, 7111348-7125387, 8015040-8050624, 8050625-8057544, 9041439-9165304, 9165303-9217755

200HP Models

• 200HP OUTBOARD (Mercury): 1558310-1866495, 1866496-2296266, 2296267-2827676, 2827677-3226957, 3226958-3537530, 3537531-4709592, 7012358-7098522, 8006265-8045198, 9016254-9157229

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

Not sure if part 20166 fits your engine? Try our parts finder tool — it’s quick and easy. Need expert help? Contact us using the buttons at the bottom of this page – text, call, or email, whatever works best for you

Trusted marine parts specialist since 1985. Competitive pricing, same-day shipping on most orders.