The auxiliary belt on my 406 2.1D shredded last week and so I fitted a
new one only to find that it has also shredded in the same way this
morning (after about 100 miles)

I discovered this only because I popped the bonnet after the engine
suddenly became really noisey. I've spoken to a mechanic mate who tells
me that this is a common fault on this engine as the noise is diesel
knock caused by the shredding belt coming into contact with the cam
belt and upsetting the pump timing.

However, this sounds a bit far fetched to me as the cam belt is
underneath all kinds of covers. However, I have no idea with this
engine so has anyone ever come across anything similar happening
before?