Maybe it's a bearing going out in the generator?
...or the impeller in the water pump is rubbing on the water pump housing?
I don't know how to check either one, though.

David Colter
pics * 1954 wrecker * [color:#009900]1948 Chevy 1-Ton[/color]
No act of kindness - no matter how small - is ever wasted ~~ Aesop