I sprayed some w40 on the side of the pully and the noise is kinda change to low pitch sound .like grinding metal bearings, how can I make the noise go away?

Serp belts will hiss or whistle when glazed, then chatter or rattle when you slick 'em up like that...either replace the belt or make sure it's not running out of line with the other pulley, like if the mounting bolts are loose...

thanks for the responds mine got a metal gringing sound I suspect its a bearing behind the pully.

thanks for the responds mine got a metal gringing sound I suspect its a bearing behind the pully.
on the 3rd day its sounds like a remote control aircraft.

noise found on the Alternator bearing got replace noise disappears.:grinyes: