M274 Engine

[cumblechook22]

Does it exhibit issues with the timing chain? Is it a dual-row chain?

[bvlenci]

It is a dual chain, and it is not an established cause of issues.

The problem with the timing gear of the M271 engine was mostly related to the camshaft sprocket wheels and the hydraulic tensioner, rather than the single row chain.

The main issue with the M274 engine is a malfunctioning thermostat, which incurs significant repair expenses relative to thermostat replacement rates for comparable engines.

[cumblechook22]

Isn't that engine electric? hence, the increased cost

[bvlenci]

Indeed, the placement (almost) under the engine block necessitates payment for three hours of labour.

[cumblechook22]

Issues and Dependability of the Mercedes M274/M270 EngineThe M274/M270 engine series have many deficient components throughout. The first component is the camshaft actuators (solenoids). Typically, after 60,000 to 70,000 miles, these engines begin to emit a certain noise when cold. This indicates deterioration inside the camshaft adjusters. In 2014, engines were equipped with upgraded actuators (part no. A2700501147) that provide extended retention.

The second issue pertains to the accelerated deterioration of the timing chain. The expected lifetime is roughly 80,000 miles, with a variance of plus or minus 20,000 miles. The subsequent issue you may face at the same mileage is turbocharger failure. The issue with the turbocharger is uncommon, although it remains relevant.

The long-term reliability of the M274/M270 is contingent upon several variables. As is customary, Mercedes vehicles require diligent care and maintenance, often more frequently than the manufacturer's prescribed timetable.

That is where I encountered the issues related to the timing chain.

[bvlenci]

While I am uncertain about the author, I can assert with some confidence that, having participated in this forum for the last 16 years, problems with the M274 engine (except the thermostat) are seldom. I own a vehicle equipped with the M274 engine for five years, and the only problem encountered was the thermostat; nonetheless, this is a singular case.

In summary, except from the thermostat, I anticipate no problems with the M274 engine.

[cumblechook22]

Thank you. I hope the thermostat has already been replaced in the Mercedes I purchase.
I drove my vehicle to a Mercedes independent garage in Chelmsford today for a thermostat replacement. They cost me £436, which is excessive for a task involving just three bolts, especially because it is easily accessible on the OM646 engine.

[bvlenci]

I am unaware of the expense associated with changing the thermostat on the OM646 engine; but, for the M274 engine, anticipate a cost of around £350 at an independent garage (including parts and work), or twice that amount at a dealership.