[SSBGLA45]

The "hours after" throws me a bit, BUT the whine/cooling fan noise is probably the after engine shut down turbo cooling pump. Obviously turbos run hot and the bearings in the units reside in a rather brutal environment and that becomes worse when the engine is turned off and bearings sit in oil that is cooking from the heat (term is called coking)…basically a turbo creates extremely high temperatures that will cause the lubrication in the turbo bearing housing to disintegrate and causes coking. A way to avoid this situation is for the cooling oil to continue to circulate thru the turbo thus the 'whine/fan running' sound of the turbo oil pump in action.