90171-18M04 Yamaha Castle Nut 115HP | Genuine Used Part

🔧 Product Description

Genuine Yamaha Propeller Castle Nut - Part Number: 90171-18M04-00

A genuine Yamaha castellated propeller-shaft nut used on a broad range of medium and large outboards.

The nut secures the propeller and spacer stack to the propeller shaft and is locked by a cotter pin through the castellations. Although listed as a 115HP part, it is documented across Yamaha engines from approximately 115HP to 350HP.

⚙️ Key Features

• Genuine Yamaha propeller-shaft castle nut
• Correct full part number 90171-18M04-00
• Castellated design accepts a locking cotter pin
• Used on standard- and counter-rotation gearcases
• Broad two-stroke and four-stroke compatibility
• Available within Yamaha propeller hardware kits

🚤 Compatibility

Documented across selected

• Yamaha 115HP and 130HP V4 two-strokes
• Yamaha 140HP, 150HP, 175HP and 200HP outboards
• Yamaha 220HP, 225HP and 250HP outboards
• Yamaha 300HP and 350HP outboards
• Two-stroke, HPDI and four-stroke engine families
• Standard- and counter-rotation lower units
• 1984 115ETLN / 115ETXN
• 1989 150ETXF
• Later F115-F350 and V6/V8 applications where 90171-18M04-00 is specified
• Fitment Requirement: Confirm propeller-shaft thread and hardware stack

🔌 Function

The nut clamps the propeller, thrust washers and spacers onto the propeller shaft. The cotter pin prevents the nut from rotating loose during operation.

⚠️ Common Signs of Failure

• Castellations are damaged
• Threads are stretched, crossed or corroded
• Cotter-pin hole will not align at the specified torque
• Propeller has axial movement
• Nut has been damaged by incorrect tools

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 90171-18M04-00 current documented Yamaha castle-nut reference
• No direct supersession confirmed

OEM / Related Numbers

• 90171-18M04-00
• 92990-18200-00 related propeller washer
• 91490-40030-00 related cotter pin
• 688-45997-01-00 related rear spacer
• 6G5-W4599-00-00 Yamaha propeller nut and spacer kit

Aftermarket / Verified Equivalents

• SEI Marine replacement for Yamaha 90171-18M04-00
• GLM 22221 cross-reference shown in propeller-hardware catalogues
• OMC / Johnson 3852020 is shown as a related cross-reference in some propeller-hardware catalogues; confirm thread and castellations before use
• Sierra 18-3792 may suit documented Yamaha propeller-shaft applications; verify shaft thread before installation
• Aftermarket brass or stainless castle nuts must match thread, height and cotter-pin alignment

📦 Condition

• Genuine used part
• In good working condition unless otherwise stated
• Inspect threads and castellations before reuse
• Install with the correct washer, spacer and new cotter pin