It might have taken over 150 pound feet of torque to intentionally strip the threads. It was a struggle even using a breaker bar. Even though most folks that don't use a torque wrench will over tighten fasteners, I can't see anyone ever coming anywhere close to mechanically breaking perfectly good threads on a Yamaha outboard motor drain pan.
Which is why my hypothesis is that over time, given sufficient tightening and un-tightening cycles, the aluminum threads crack and break. Those are cut threads I believe. Not rolled threads. Cut threads are more susceptible to cracking at the root of the thread. Everything is fine until one day it is not.
Maybe.
Which is why my hypothesis is that over time, given sufficient tightening and un-tightening cycles, the aluminum threads crack and break. Those are cut threads I believe. Not rolled threads. Cut threads are more susceptible to cracking at the root of the thread. Everything is fine until one day it is not.
Maybe.
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