Now that I see the bike maybe the noise arent the cranks... maybe are the pedals, a bb cup, or the stem/handlebar. Unless he heard that thing all the time. and if thats the case I dont think are the cranks at all or a BB cup. Usually cranks are noisy when u go over the pedals and only in one position, when seated they dont do any noise. The stem/handlebar do noises time to time if isnt tighten enough. It could be an spoke. Did u check the spokes in the rear wheel?

UM