I've got some strange noises coming from what seems to be the alternator. My question, is the small fan on the front of it supposed to turn by hand? Although not very free, it turns both ways.

 

nope not unless your turning the engine over along with it or the fan & pully together are spinning around & that would just be a loose belt & i doubt thats what you are saying the nut that holds the pully & fan is suposed to be put on with an impact if it was changed at some point from an old alt to a new one it might not have been put on correctly no point in trying to tighten it by hand it will eventually come loose again if you cant get an impact on it take it off the car & do it or take it up to someone that has one & have them tighten it for you left alone it will more than likely get worse & at some point your more than likely gonna loose your pully & fan off the alt & then the belt so everthing that it drives like the water pump & your basicly stranded waiting for a tow truck

 

Thanks for the reply The alternator is off the car now, and yes the whole fan and pulley are rattling around loose. I've got a replacement one coming now.