My Alfa was down last week while I changed the clutch and flywheel so I got a week commuting in the wifes Bis. It ran well until there was a small "bang" followed by even more rattling than usual. Turned out that the "adjuster" bracket for the alternator had sheared in two at the block. Fortunately, I was able to source a rapid replacement from the spare engine. However, it was immediately apparent that the cause was the alternator being too loose on the pivot so it was stressing the bracket (and also causing the rattle that I couldn't pin down). The pivot bolt is quite a loose fit in the engine casting so relies on the whole thing clamping tight to avoid it rattling. There is the small movable sleeve that is designed to take up some slack but on mine it was not long enough so even with bolt tight there was a fair bit of movement. Thus, I needed to add quite a thick washer before the whole thing would snug up nice and tight. I don't know if this is a common fault but might be worth checking....
Keith
