Description Of Engine Om 651 - Mercedes-Benz Series 176 Introduction Into Service Manual

4-cylinder diesel engine OM 651
The familiar 4-cylinder diesel engine OM 651 is
available in the new A-Class in two displacement
and three output variants.
The characteristic features of this engine include:
• 1.8 or 2.2 liter displacement
• Common rail, max. injection pressure 1800 bar
• Solenoid injection valves
• Variable nozzle turbocharger
• Load point offset towards reduced consumption
(downsizing)
• Reduction of emissions through multiway
exhaust gas recirculation
• Volume-controlled oil pump with two pressure
stages
• Switchable coolant pump
• ECO start/stop function
• Compliance with EU5
4-cylinder diesel engine OM 651.901
– This printout will not be recorded by the update service. Status: 06 / 2012 –

Description of engine OM 651

Multiway exhaust gas recirculation
On the OM651 engine with multiway exhaust gas
recirculation (MW-EGR) the drivetrain control unit
actuates and regulates all sensors and actuator in
the multiway exhaust gas recirculation system.
The engine exhaust gas recirculation actuator is
actuated on the basis of a filed characteristics map
with a pulse width modulated signal (PWM signal).
The exhaust gas recirculation actuator increases or
reduces the volume of recirculated exhaust, which
is routed over a mixing tube downstream of the
throttle valve actuator into the charge air manifold.
To enhance the effect of the EGR, the exhaust is
routed and cooled through an exhaust gas recircu-
lation cooler. If the temperature of the recycled
exhaust is too low, the exhaust can be routed
through a bypass duct and past the exhaust gas
recirculation cooler. The switchover valve bypass
for the exhaust gas recirculation cooler is then actu-
ated through a map control using a ground signal
and the bypass in the exhaust gas recirculation
cooler is opened.
Introduction of the New A-Class, Model Series 176
P01.10-3062-00
b 41