Is that coming from inside the engine? If you're not sure, I'd start by removing the serpentine belt to see if a pulley is binding causing the tensioner to bounce back and forth. If the noise is still there, head for the timing chain or belt to see if a hydraulic adjuster has collapsed.
Also look for a sagged engine mount that is letting the fan hit the shroud, assuming it's a belt-driven fan.
Monday, May 30th, 2011 AT 12:18 AM