alternator tensioner bolt

[RagingPanda]

This is the second times it happened while driving on the highway. The bolt just snapped in half. I know the problem and how to fix it but what I want to know is why. What is the cause so I can prevent this from happening...again.

[allenms240]

get a higher grade bolt?Really not much to it. MY alternatoer tensioner bolt used to come out of the alternater and I'd lose it while driving. IDK why.But I got a slightly larger bolt, and forced it in the threads, now its tight:)But yea, higher grade/stronger bolt.