Updated diesel engine above board: Mercedes

MERCEDES-BENZ says that the 2.0-litre OM654 unit in the updated C-Class mid-sizer will not attract the attention of its 2.2-litre predecessor, following the mandatory recall of 774,000 turbo-diesel engines in Europe due to the alleged fitment of illegal emissions defeat software.

As GoAuto has reported, Germany’s transport ministry ordered Mercedes-Benz to recall its passenger vehicles and vans fitted with its 1.6- and 2.2-litre engines, the latter of which is offered in Australian examples of the C220d mid-sizer and GLC220d SUV.

Mercedes-Benz Australia/Pacific is still awaiting instruction from Germany as to whether it needs to take action.

Benz has denied any wrongdoing, but has agreed to apply a software fix to affected German-spec vehicles.

However at the launch of the updated C-Class in Germany, one senior powertrain official told GoAuto that the new 220d variant should not require any software updates.

The 2.0-litre engine powering the new 220d – which is also found in the current 250d – has been revised to include a new exhaust after-treatment system that is now mounted closer to the engine block, allowing the system to reach its optimal operating temperature quicker from a cold start, which makes for lower engine emissions.

Other advancements to the new engine include a stepped-bowl combustion process, an aluminium engine block replacing the old cast-iron block, resulting in a 35-40kg weight reduction, and improved cylinder wall coating and air ducting on the intake and exhaust sides.

While the 2.0-litre engine in 220d guise outputs 143kW/400Nm, Mercedes says the changes have allowed for power outputs of up to 180kW, comparable to most six-cylinder diesel engines.

As a result of the changes, the OM654 engine is certified for Euro 6D-Temp emissions standards, the highest currently achievable.

The new donk continues to use the AdBlue additive system to help reduce emissions, which was the cause of concern for the old OM651 diesel mill.

The allegations levelled against Mercedes claim that the engine software fault caused the amount of AdBlue – which helps reduce levels of nitrous oxide in the exhaust gases – to drop after a certain amount of time.

The number of Australian vehicles affected by the recall is expected to be relatively small, as local customers have shown a preference for petrol-powered C-Class variants. The C220d and C250d are the only diesel variants in the outgoing C-Class range.