Mercedes dealerships in Brazil claimed that the premature wear of the cylinder head and exhaust valve guide on the M260 or M264 engines, used in A, CLA, GLA, or GLB models manufactured between 2019 and 2022, was caused by gasoline problems, either due to adulteration or high ethanol content. Consequently, neither the dealerships nor the factory assumed responsibility for the damage.
However, specialized workshops, such as the High Torque network in São Paulo and Autocentro Bosch Confiar in Contagem, investigated vehicles with this defect. The investigation revealed that the brand's headquarters, located in Germany, had instructed the dealerships to extend the warranty for these engines to 15 years or 150,000 miles (equivalent to 241,000 km).
Additional Information
In Brazil, the consulted factory refused to comment on the issue raised by the report. The dealerships, in turn, stated that when they receive cars with the problem, the solution is evaluated on a case-by-case basis. This may result in an extended warranty at no cost to the owner, or a courtesy of 50% of the repair cost, or Mercedes does not charge for the new cylinder head, but the customer pays for the labor at the dealership.
There is a perception of hypocrisy in charging any amount for the repair of a defect originating from a manufacturing error admitted by the headquarters in Germany. Since the problem was not classified as a safety issue, there was no recall of the affected vehicles. However, by recognizing the fault and the potential increase in emissions due to irregular engine operation, the factory recommends free repair for the owner through a Technical Bulletin.
The defect lies in the cylinder head, which has intake and exhaust valves; specifically, the seat where the exhaust valve rests suffered premature wear. This wear usually occurs at higher mileage, starting from 50,000 km, at which point the vehicle is theoretically no longer under warranty. Signs include irregular operation, idle failure, and loss of performance. In more serious cases, the loose part can cause damage to pistons and cylinders, and irregular combustion increases the level of gaseous emissions through the exhaust.
Mercedes-Benz in Brazil shows greater attention to its heavy vehicles (buses and trucks), but less to passenger cars. The company has already attempted to produce cars in the country twice without success: the A-Class in Juiz de Fora (between 1999 and 2005) and the GLA SUV and C-Class in Iracemápolis (from 2016 to 2020), before shutting down the factory, which was later sold to the Chinese GWM. Currently, the German brand holds only third place in the luxury car segment in Brazil, behind BMW and Volvo.
The negligence of the Brazilian branch is also reflected in the owner's manuals, which use an edition intended for Portugal, which does not advise using gasoline with more than 10% ethanol, while the Brazilian manual indicated 27% (E27).
The NHTSA, the US government safety agency, received complaints about this fault and issued an official statement:
Warranty Extension
Mercedes-Benz recognized the defect and granted a warranty extension covering the engine cylinder head for up to 15 years or 150,000 miles on affected vehicles, such as the A-Class, CLA, GLA, and GLB models. To check specific coverage, one must contact a local dealership providing the chassis number (VIN).