I have a 2001 ML320 and when I start the car it makes this clicking noise. It happened few weeks ago and it still happening. I mainly hear it when slowly accelerating and standby because it gets louder. Noise doesnt go away at all. Sometimes the noise is a little more subtle. Any possible reason why this would happen? Harmonic Balance? Exhaust leak?

I think the noise is coming from the front of the engine when facing the front of the car(look at pic 1) where the fuel regulators are or closet to the serpentine belt and the rear of the engine adjacent to the firewall

miles:99,000

pic 1
http://i126.photobucket.com/albums/p...3/NewImage.jpg

 

could be just the valve lifters ....hard to say for sure...if your talking about the 2 gold valves they are for supplying air to the engine the fuel regulator is in the fuel filter.

 

forgot to mention. seem like its coming from the internal of the engine