Jurgeenh

I have a CLS500 2006 with 28k miles and its making the same noise as the CLK500 that buzzing noise on c-case, i use a sthetoscope and the buzzing its just in the front of the c-case if you put the steto just above the harmonic balancer (really close to harmonic) on the block you still hearing the noise, makes me think that could be the harmonic itself, but it sound only on cold during a period of 5-7 minutes, when engine its warm it sound nice and quiet, here is the video of the CLK.
http://m.youtube.com/watch?v=G0iP2UMwW5A

cmriv

upper idler pulley?

Jurgeenh

No, its not an accesory, i tried removing the belt and still same noise, must be internal or the crankshaft pulley but i want to know if any one else had this issue before how they solved?

Jurgeenh

Hello...

cmriv

Never heard a cranshaft pulley making noise. They separate but that is about it. Is your sbc pump making the buzzing sound.... Those can be really noisy at times.

Jurgeenh

But you can hear that noise on the crankshaft, thats the weird thing or on the engine in front just on cold starts, its the same symptoms for the sbc pump?

cmriv

Maybe it is your airmatic pump. IDK. You are being pretty vague on describing the buzzing noise. At cold start i understand but does the noise increase when rpm's increase? does it do it while driving?