just bought an 03 C240 (V-6 non-supercharged), exellent car however my car has a loud spooling noise, kinda sounds like a supercharger when you rev the accelerator, is this normal? the sound seems to be comming from the Idler pulley. any suggestions? besides the ovious change the got dam idler pulley?

 

Maybe you need belt replaced?

 

Found the problem, idler pulleybearings seized, so the whole pulley assembly is spinning on the bolt that holds the pulley assembly to the engine. Easy $20.00 Fix