Yamaha Outboard Nylon Lock Nut - 90185-05904-00
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The Yamaha 90185-05904-00 is a genuine Yamaha OEM nylon self-locking nut used in select Yamaha outboard assemblies where the factory parts diagram calls for this exact fastener. This lock nut uses an internal nylon insert to help resist loosening from vibration, making it suitable for small hardware locations such as water inlet screens, linkage brackets, tiller components, and other diagram-specific mounting points.
Use this nut only where the Yamaha parts diagram specifically calls for 90185-05904-00.
Key Features
- Genuine Yamaha OEM locking nut.
- Yamaha part number: 90185-05904-00.
- Alternate formatting: 90185-05904 and 901850590400.
- Nylon insert locking design helps resist vibration loosening.
- Commonly used in small Yamaha outboard hardware locations where specified.
- Listed weight reference: 0.004 lb.
- Suitable for replacing missing, corroded, loosened, stripped, or previously removed lock nuts in factory-specified locations.
- Often used with matching Yamaha hardware shown in the same diagram.
Application Compatibility
Common application context includes select Yamaha 2-stroke and 4-stroke outboards by model, serial number, and diagram location, including:
- Select Yamaha 6 HP through 350 HP outboard applications where specified.
- Lower unit water inlet screen / water intake screen mounting locations where the diagram calls for this nut.
- Tiller handle, steering, throttle, shift, choke, and linkage bracket locations where specified.
- Select lower casing and cowling-related hardware positions where Yamaha calls for 90185-05904-00.
- Applications using related Yamaha screen screw 90152-05003-00, where shown together in the factory diagram.
Fitment must be confirmed by the exact Yamaha parts diagram before ordering.
Serial Number Fitment Notice
Confirm fitment by Yamaha model code, serial number, horsepower, assembly diagram, thread size, matching screw, and hardware location before ordering. Yamaha uses many similar small lock nuts across outboard assemblies, and similar-looking fasteners can differ in thread, material, height, locking style, and intended service location.
When This Part Needs Replacement
Replace this lock nut if the nylon insert is worn, loose, melted, cracked, contaminated, stripped, or no longer grips the screw threads securely. It should also be replaced if the nut has been removed from a vibration-sensitive location such as a lower-unit water screen, control linkage, tiller bracket, or shift hardware location. Reusing a worn nylon lock nut can allow hardware to loosen during operation.
Installation Notes
Install this nut only with the correct Yamaha screw or stud shown in the factory diagram. Make sure the threads are clean and undamaged before assembly. Tighten to the Yamaha service-manual specification for the specific location and avoid overtightening small hardware, especially on plastic screens, aluminum lower casings, linkage brackets, and thin mounting tabs.
If servicing water inlet screens, inspect the screen, screw, threaded hole, and surrounding lower casing while the hardware is removed.
Alternate/Superseded Part Numbers
- 90185-05904-00 — Yamaha OEM part number
- 90185-05904 — alternate catalog formatting
- 901850590400 — condensed catalog formatting
- 90185-05002-00 — earlier Yamaha reference; verify by model and diagram
- 90185-05M00-00 — earlier Yamaha reference; verify by model and diagram
- SEI Marine 98-416-32 — aftermarket reference; verify by application and thread before substitution
Parts Desk Insight
Small lock nuts are easy to overlook, but they are important on marine engines because vibration, salt exposure, and repeated service can weaken the locking insert. For lower-unit water screens and linkage hardware, replacing the nut when it has lost grip helps prevent loose parts, missing screens, and repeat service work.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
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Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
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