— Mercedes M274 engine problems caused a vehicle owner to petition the government in 2022 requesting a formal investigation of alleged problems with the wrist pins.
In 2022, Mr. Sergio Betancourt submitted a petition attributing his 2015 Mercedes-Benz C300 M274 engine failure to “wrong sized wrist-pins.”
The petitioner contends M274 engine problems are widespread on all Mercedes-Benz models equipped with versions of the M274 engines, including the Mercedes Metris, GLC300 and Mercedes C300.
The petition references technical service bulletin (TSB) LI03.10-P-060916 issued for 2015 Mercedes C300 vehicles. The petition alleges the “wrong-sized wrist pin” would allow the piston to “wiggle in the cylinder as it would move up and down.”
"In the incident that prompted the petition, the petitioner reported that the vehicle lost power and shook in response to accelerator application during highway driving, followed by white smoke from the exhaust pipe. The petitioner stated that the subsequent service center visit led to a cracked piston diagnosis." — NHTSA
TSB LI03.10-P-060916 was first released in February 2015 and pertained to engine code 274.920.
“Clattering/rattling or knocking noise from the crank assembly of the engine when cold at oil temperatures up to approximately 50°C mostly heard on engine deceleration” and listed the cause as "under analysis."
Mercedes dealers were told not to replace any components.
Mercedes-Benz responded to NHTSA in November 2022 and said the limited number of potentially affected wrist pins could contribute to an unintended noise, but it was not a risk to vehicle safety.
Safety regulators could find no relationship between wrist-pin conditions mentioned in the TSB and engine failure or loss of motive power. NHTSA also found no trends related to Mercedes M274 engine problems.
In denying the petition to investigate the M274 engines or wrist pins, NHTSA says it will continue to monitor any new incidents submitted to the government.
