I had this rattling/buzzing noise at around 3k rpms. I took it to a shop and had and exhaust piece rewelded. It was some piece that touches the oil pan. THe noise stopped but it started once again and i had them reweld it again. That fixed it for about a week and a half and now it is doing it again. Does anyone know why it keeps on reocurring? Its really annoying!

 

anyone?

 

there was a post on this at preludeonline.com that I started. Do a search on 'buzz'
Its the bracket from the header thats connected to the back of the block.

Your might be breaking again after they're rewelding it.