Sound from motor
 

It only seems to happen when the truck heats up and I'm driving it. It sounds like your flicking a piece of thin sheet metal or something on that order usually three times in a row. I have no idea. Looked around in the engine and underneath, but nothing loose and like I said only happens when I'm driving, so can't go underneath while truck is running and listen for it. Any ideas cause I'm definately confused? :argh: