How reliable is the Mercedes C class?

In this article, we find out how reliable the Mercedes Benz C class is and answer the following questions: What is the service interval of the C class? What are the materials and engine options available in the C class? And lastly, some tips to improve reliability 

How reliable is the Mercedes C class?

The Mercedes Benz C class is one of the most reliable models in the Mercedes Benz line-up. The Mercedes Benz C class can easily last for more than 10 years and cover 100,000 KM without any major repairs. 

Mercedes Benz also provides an extended warranty from the fourth to the sixth year of purchasing the car. Advanced assurance programs further help to increase reliability by covering the cost of any unexpected repairs.  

A special goodwill gesture is provided for the repairs if the vehicle is no longer in the warranty period. Service packages like star ease plus can be bought which can cover the cost of servicing for up to 10 years. 

The Mercedes Benz C Class model series W205 is a standard sized sedan from Mercedes Benz. It is also available in the AMG line and AMG 63 model series. The C class coupe comes with a 4MATIC all-wheel-drive system. The C class comes in a soft-top convertible and AMG line model in a 2 door coupe. 

Currently, the C class is in its sixth generation and starts with the model series W206. It also features an integrated starter generator and a 48V high voltage electric system. Mercedes Benz C class offers a wide range of engines, driver assistance and safety systems that can meet any requirement of customers. 

Thanks to integrated starter generator features like pre-entry climate control, a remote parking pilot can prepare the vehicle for the journey even before the customer enters the vehicle.

What are the engine options in the Mercedes Benz C Class?

Mercedes Benz has inline 4 and 6 cylinder petrol and diesel engines. AMG and AMG line models also use V6 and V8 engines which produce more power compared to standard models.  Engines in petrol variants are M274, M264, M276 and AMG M177. 

The petrol engine produces power between 115kW till 225kW and AMG produces up to 375kW. M274 is replaced by the M264 engine.

 M264 is also available with a 48V belt-driven starter and alternator or integrated starter-alternator in the W 206.  All the ancillary components like the coolant water pump, air conditioning compressor are electric.

Diesel variants use OM 654 in different states of tune with the AdBlue injection system for exhaust after-treatment producing a maximum power output of 140kW and 400NM torque.  

It is equipped with low and high-pressure exhaust gas recirculation to reduce NOX emissions. AdBlue injection with selective catalytic reduction can be also found in the latest models. These exhaust gas after-treatments are present to meet emission regulations.

Materials used in manufacturing petrol and diesel engine components.

Engine block or commonly known as crankcase is the foundation of any engine. Petrol engine blocks are made up of aluminium alloy while diesel engine blocks are made up of cast iron.

The reason for the change in materials for diesel and petrol engines is because diesel engines are self-igniting, the compression pressure in diesel engines is up to 30 bars. Hence, the material of the engine block must be strong enough to sustain high combustion pressure. 

Closed deck engines are more commonly used in Mercedes Benz diesel engines. This type of construction provides more support to the cylinder walls and water jackets can be designed around the cylinder sleeve for better cooling. The use of closed deck design along with cast iron metal makes up for heavy engines.

Open deck design is more commonly used in Mercedes Benz petrol engines. The compression of a petrol engine is between 11 to 16 bars which are very less compared to a diesel engine. This constitutes less combustion pressure and aluminium alloy can be used for the construction of the crankcase.

Cylinder heads for both petrol and diesel engines are constructed using a special alloy of aluminium metal. The cylinder head houses intake and exhaust valves, rocker arms with rollers and hydraulic lifting elements.

Mercedes Benz uses NANOSLIDE coating on the cylinder walls. This is an extremely thin coating applied to the inner surface of the cylinder to reduce friction between the piston. Twin-wire arc spraying (TWAS) is used to spray an extremely thin coat of iron-carbon alloy on the cylinder walls.  The friction between the piston and piston rings is reduced by almost 50 per cent.

Special features are found in Mercedes Benz to increase reliability.

  • Warm-up phase- When the engine is started for the first time, engine oil and coolant temperature is low. The engine is designed to operate at a specific operating temperature and must also reach this operating temperature quickly regardless of the outside temperature. Hence, in the warm-up phase, the engine idles at slightly higher RPMs for a few minutes after starting the engine. This also ensures the engine oil is circulated to the entire engine.
  • Radiator shutters- aerodynamic flaps are not only present on the outside of the vehicle but also inside the vehicle. Flaps cover the surface of the radiator and are operated by a vacuum actuator. 

By closing the flaps air does not flow over the surface of the radiator and coolant can heat up faster which is then pumped back into the engine and the operating temperature is reached more quickly.

  • Multi-Spark ignition system. This is only used in petrol engines. Spark plugs generate an ignition voltage of 15000 to 45000 volts in a Mercedes Benz petrol engine. Multi spark mode is active during the warm-up phase and instead of discharging the ignition coil completely, it is changed again in small intervals. This results in multiple sparks which increase the combustion temperature and the engine can reach the operating temperature more quickly.

Common practices increasing the Reliability of Mercedes Benz cars

  • After starting the engine, wait for a few seconds so the warm-up phase can finish. This also makes sure the engine oil is circulated entirely in the engine.
  • Never operate the engine in full loads for an extended duration, keep the RPMs fluctuating. Operating an engine at constant or high rpm puts unnecessary strain on the engine components.
  • Visually inspect the engine compartment for visible oil or coolant leaks. If the oil or coolant level is low then the engine can be damaged due to overheating.
  • Consult the workshop if an EOBD malfunction or abnormal noise is coming from the engine while driving.
  • Follow the service schedule and replace parts like air filters, fuel filters etc so the engine can continue to function properly.

What is the service schedule of the Mercedes Benz C Class?

Mercedes Benz C class service intervals are every 15000 km or 1 year, whichever comes early. During service of the engine, the engine oil and oil filter is replaced. If the vehicle is used in dusty areas, air filters are also replaced.

If the engine oil and oil filter is not replaced periodically then engine oil loses its lubricating properties and can no longer do an adequate task of lubricating moving parts.

The engine oil filter is also a very critical component as it filters small metal shavings in engine oil which can scratch and damage bearings inside the crankcase. Small particles if left unfiltered in the engine can block the lubricating path or oil spray nozzles and cause wear to components like the timing chain, valves, connecting rods and cylinder walls.

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Mercedes Benz is the second most selling model after the E class. The older generation of the C class had some reliability issues related to the wheel speed sensor and ESP control unit. However, thanks to extensive testing and modifications the newer models are one of the most reliable and safest cars on the road.

FAQs: How reliable is the Mercedes C class?

Is Mercedes-Benz C-Class reliable?

Yes, the Mercedes Benz C class is one of the most reliable Classes in the Mercedes Benz product range. All the reliability issues in the old generation of C class has been addressed by Mercedes Benz in the facelift and latest model.

Do Mercedes C Class last long?

Yes, Mercedes Benz C class are designed to be a durable car. A C class can easily stay in good working condition for 10 years.

What problems do the Mercedes C class have?

The older generation of the C class had few problems with the ABS/ ESP system. Mercedes Benz has resolved the issue by introducing replacement parts.