Noise from oil pan?

[Big hammer]

A loose pulley on the end of the crankshaft could be the cause of your noise.

 

[katy]

Removed the belt from the alternator and noise seems to have gonna away. Maybe the alternator bearing is toast?

If'n the nut on the alternator shaft is loose, it may be the fan on the alternator making that rattling noise. try spinning the alternator by hand.