OMC Cobra SX & DP-S Duoprop Stern Drives Shop Manual 1994-2000
Several types of bolts, screws and nuts incorporate a system
that creates interference between the two fasteners. Interference
is achieved in various ways. The most common
type is the nylon insert nut and a dry adhesive coating on
the threads of a bolt.
Compared to standard fasteners, self-locking fasteners
offer greater holding strength, which improves their resistance
to vibration. Most self-locking fasteners cannot be reused.
The material used to form the lock becomes distorted
after the initial installation and removal. Discard and replace
self-locking fasteners after removal. Do not replace
self-locking fasteners with standard fasteners