Repair manuals and video tutorials on MERCEDES-BENZ C-Class

Engine

• Cylinder head deformation of a 6-cylinder in-line M104 petrol engine is caused by its overheating. If there are leaks from under this assembly, visit a car repair shop to have the cylinder head grinded. Regularly change and top up motor oil and coolant. Read our illustrated PDF manual on Mercedes-Benz C-Class repair  to do it yourself.
• Owners of W204 cars with 2.2-litre diesel motors experience a premature water pump bearing wear-out. The humming noise is the evidence of this defect. Use high-quality coolant and check its level regularly to extend lifespan of the pump. Visit a car repair shop for the component replacement.
• An exhaust gas recirculation valve of diesel engines with mechanical supercharger clogs with soot at about 50,000 kilometres. You can easily recognize this problem: black smoke from the exhaust pipe, unstable idling speed of the power unit and reduced output. Our recommendation is to install a new part at a car repair shop, as it requires further adjustment.

Transmission

• First and second speed synchronizers of the manual transmission may fail. If the gear shift requires extra effort and you hear a crack when engaging a lever, visit a car service station to have this assembly repaired. Remember to timely change gear oil. To do this, download our step-by-step video tutorial on Mercedes-Benz C-Class repair for free.
• Automatic transmission seals may leak. Visit a car repair shop to have the new components installed.

Steering 

• A hydraulic power steering pump malfunctions. Its bearing may jam and seals – leak. This component should be replaced as an assembly by professionals. To prevent this issue, monitor the level and condition of the hydraulic steering oil. Change it at least every 50,000 kilometres unless the car manufacturer states otherwise. Do not hold the steering wheel in its extreme position more than 5 seconds to avoid pump overload.
• A steering rack of W203 cars fails after 80,000 kilometres. If this is the case, you will hear knocks while driving on road irregularities. The steering rack can be mostly restored with the help of a repair kit. Download our video guide and follow the instructions on Mercedes-Benz C-Class repair and operation step by step.

Electric equipment

• The rear light contacts and housings of W204 cars get melted due to ingress of moisture. You can install new components in your garage. To do this, read our manual on DIY Mercedes-Benz C-Class repair and maintenance.
• SAM control unit contacts get oxidised. If the central locking system or sensors malfunction, contact automotive electrician to have the assembly replaced.