Harmonic balancer pulley bolt
 

I have been searching the web and noticed there are a lot of harmonic balancer pulley failures and woodruff key problems. I presume these are caused by insufficient bolt torque.

Is the bolt thrown away and replaced with a new one at each change of balancer or cam belt replacement? I can't find any mention of it. I was wondering if it is a stretch bolt like the cylinder head bolts.

Crank pulley bolt is usuallly ok. I wouldnt call it common to have issues with them or the keyway on the crank.

But it is common for the cam pully bolts to be siezed. Quite often getting quite chewed up during removal, in someinstances needing to be cut/drilled out