I don't know what it is but, whatever it is it's driving me crazy. I can hear it at idle and when I'm just driving along. I thought that it maybe the Timing belt or something like that. I don't have smoke coming from the engine, and I don't smell oil burning. When I crank it up it goes clack, clack, clack, and if I hit the gas it just speeds the sound up. The car is bone stock and it seems to run aight, but this noise is really bothering me. It almost sounds like it's coming from underneath the left side of the engine. Does anyone out there have a clue to what I'm talkin about? Any help would be greatly appreciated. Thanks in advance.