Engine Mercedes OM647

Engine Mercedes OM647

The OM647 engine is a 5-cylinder in-line diesel engine manufactured by Mercedes-Benz. Displacement 2.7 liters, 4 valves per cylinder, DOHC, common rail direct injection, turbocharging. Cast iron block and aluminum cylinder head. Model 647.961 was installed on Mercedes 211 W211 S211 and other models.

It was produced only in two versions – 647.961 (installed on 211.016 / 216) and 647.981. The cars bore the trade designation E270 CDI. The internal designation of the engine is OM 647 DE 27 LA. Displacement – 2685 cc, cylinder bore – 88.0 mm, piston stroke – 88.3 mm.


Displacement, cc 2685
Power, hp (kW) at rpm 177 (130) / 4200
Torque output, Nm (kg-m) at rpm 400 (41) / 2600
425 (43) / 2000
425 (43) / 2600
Fuel type diesel fuel
Fuel consumption, L/100 km 6.8 – 7.2
Configuration inline, five-cylinder
Cylinder head DOHC
CO2 emission, g/km 180
Cylinder bore, mm 88
Valves per cylinder 4
Supercharger Turbine
Compression ratio 18
Piston stroke, mm 88.3

Features of OM 647

OM647 uses five cylinders. The engine is operated with a VGT or VNT turbocharger. The boost pressure is up to 1600 bar. There are 2 camshafts on the motor, the drive is carried out using a timing chain. There are 4 valves per cylinder, adjustable by pushers. There is an electronically controlled EGR valve. The control unit also controls the fuel pump, and the fuel is supplied metered.
Engine Mercedes OM647 under the hood
Pre-injection, which means that a small portion of the fuel is burned before the main process. This makes it possible to heat the chamber, which contributes to a quick start and warm-up of the motor. Of course, the temperature regime and the pressure parameter are better maintained. Some modifications of these engines are equipped with a balance shaft rotating opposite the crankshaft at a higher speed.

Typical faults and modifications

  • the fuel system fails frequently;
  • crankshaft bearings rotate;
  • particulate filters are deteriorating;
  • Intake manifold flaps wear out prematurely.

OM647 has two modifications: 961 with 163 hp. at 4200 rpm and 981 with 156 hp. at 4200 rpm.

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