A Brass Nylock prop nut (OEM part number 11-827614) is designed to stay securely in place on Mercury Marine and Mercury Racing outboards. If it loosens over time, it is likely worn out and requires replacement. A loose prop nut can lead to excessive propeller vibration, which may cause internal gear damage in the lower unit.
 
Excessive movement of the propeller can result in gear chipping inside the lower unit. In some cases, the nut can completely back off, leading to a lost propeller. To prevent this, the prop nut should be torqued to approximately 55 ft-lbs until a flat surface of the nut aligns with a washer tab. After alignment, one of the washer tabs should be bent up to secure it in place.
 
Repeatabley re-using an old or worn-out Nylock prop nut is not recommended. Once a nylon lock nut has been installed, the nylon insert deforms, reducing its locking strength. Removing and reinstalling the same nut compromises its ability to stay secure, increasing the risk of loosening.
 
The FAA advises that nylon locking nuts should not be reused if they can be turned by hand once the locking insert engages the threads. This principle extends to marine and high-performance outboard prop nuts, where securing your propeller is essential for performance, gearcase longevity, and safety. When in doubt, always replace the nut to ensure reliability.
 
Mercury OEM Part Numbers:
11-52707A 1
11-52707Q 1
11-827614
 
Includes one (1) Brass Nylock Prop Nut for Mercury Marine and Mercury Racing applications.
 
For inquiries, contact mike@buckshotracing77.com or call Mike directly +1-714-697-1716.