The Mercedes C Class is one of the highest-selling model lines for the Mercedes automotive corporation. The vehicle uses a single drive belt called a "serpentine" belt to run all of the engine's accessory components, like the alternator, air conditioning, power steering and water pump. It uses the power from the crankshaft pulley to run everything. When the belt wears out, you will hear a squealing sound. This tells you that the belt is slipping on the pulleys.
Locate the pulley routing diagram printed on the underside of the engine hood. If the diagram is missing, it is important that you make your own diagram. The drive belt must route properly around each pulley to ensure the accessory runs properly.
Locate the tensioner pulley on the lower half of the engine, close to the crankshaft pulley located in the centre of the engine. The pulley has a square hole in the centre of it.
Place the three-eighths-inch ratchet drive into the square hole, and lift up on the handle. This releases tension on the drive belt. Slip the drive belt off the tensioner pulley.
Remove the drive belt from the other pulleys, and then route the new belt onto all the pulleys except the tensioner pulley. Use the diagram to help you.
Lift up on the ratchet handle, and slide the drive belt over the pulley. Let go of the handle, and remove it from the tensioner pulley to create tension on the belt.