One problem related to engine belts and pulleys has been reported for the 2004 Mercedes Benz C230. The most recently reported issues are listed below.
Mercedes C230 kompressor. The bolt that holds the alternator belt has broke 3 times! when the belt slipped it affected the power steering and I was unable to steer! very scary, luckily I was driving under 25 mph at the time. There must be a default in the design for this to keep happening!.