If the metal outer ring was allowed to vibrate, because of a deteriorating rubber insulator, then the whipping action, of the heavy, outer ring, would be transferred to the inner metal ring, attached to the crankshaft.
If the bolt holding the 5#+ pulley loosened, then the whole assembly would beat itself back and forth, hammering the key.
I never use Locktight (blue) on my crank pulley bolt, but you might.
|