There are a number of possible causes, but rather than guess, please follow these direction to isolate the sound.
Leave the car running in idle, do you still hear the clank?
Move around the car from driver side to passenger side and see if you can narrow the location of the sound.
Nothing on this engine moves except on the front of the engine (front of engine is on the passenger side.) Here you have (standard) cranck shaft pulley, camshaft pulley, alternator pulley, power steering pump pulley and the air conditioning pump pulley. There is also 1 idler and one tensioner. The belt that connects them all is a serpentine belt.
This is the only location for EXTERNAL movement. Everything else is internal.
The variation on causes are too numerous to list here. So, try and identify more closely where the sound is coming from and reply with more information.
Saturday, January 5th, 2013 AT 7:42 PM