Fan blades? There shouldn't be a fan on a TR4 engined Morgan unless somebody has added one? The Triumph TR range had a fan driven from the crankshaft but for a Morgan application it would foul the cross head.
I'd agree with Andy G it it may be the water pump bearing and seals. If so, I'd advise fitting an uprated water pump, the latest have more vanes on the impeller and are supposed to move the move the water round quicker!
Careful use of a large (18" plus) nylon handled pry bar as a listening stick should help eliminate worn bearings in either water pump or dynamo - they do give off a pretty distinctive sound when worn!
Arwyn
