I went ahead and changed out the old ac belt for the first time in my ownership. I unfastened the two bolts holding the bracket with the idle pulley and slipped the belt on. When I went to tighten it all down, I noticed there were strips of aluminum on the thread of the bottom bolt, so the PO must have over-torqued it. I can get it snug but it'll spin in place if I try and tighten it down.

What options do I have to repair the hole? Helicoil? And does that hole go all the way through into the crankcase? My main concern now is potential oil seepage.

Thanks.