[Aussie Keith]

At 66k km and for no particular reason a terrifying noise is being emitted from the engine at idle. Turns out its just the serpentine belt idler pulley and strangely goes away off idle. I've a temporary workaround in place by turning up the radio at the lights. So far so good.

[The Gonz]

Generating that noise is still a sign of undue friction and therefore premature wear.
I would be applying lubricant to the pulley into it stops.