CDI engines: operating characteristics

CDI engines: operating characteristics

CDI are diesel engines with the Common Rail direct injection system, installed on different models of Mercedes-Benz cars. These engines appeared in 1997. They feature 4, 5, 6 or 8 cylinders. They are equipped with chain drive, turbocharger, mostly with intercooler. 2-stage turbocharger is installed on modern versions; AdBlue agent injection system is also met – it serves for reduction of harmful emissions in exhaust gases.

CDI engines consume relatively low amount of fuel, are eco-friendly, offer more power and higher torque. Such renowned manufacturers, as Bosch and Delphi, produce injection systems for such motors.

Popular CDI engines

Index Quantity and arrangement of cylinders Quantity of valves Capacity, l Output, hp Torque, Nm Production years Mercedes-Benz models
OM612 5, in-line 20 2.7 156–170 330–400 1999–2007 C-Class W203; CLK-Class C209; E-Class W210; ML-Class W163; G-Class W463; Sprinter W901.
ОМ651 4, in-line 16 1.8 and 2.2  109‒204 250–500 2008 till present A-Class W176; CLS-Class W218; S-Class W222; SLK-Class R172; GLA-Class X156; M-Class W166; Sprinter W906; V-Class W639; E-Class W212; C-Class W204; C-Class W205; B-Class W246.
ОМ656 6, in-line 24 3.0 286–340 600‒700 2017 till present CLS-Class C257; S-Class W222; E-Class W213; G-Class W463.
ОМ642 V6 24 3.0 184–265 400–620 2005 till present C-Class W204; CLS-Class W219; E-Class W211; E-Class W213; CLK-Class C209; CLS-Class W218; E-Class W212; R-Class W251; S-Class W222; GL-Class X164; GLC-Class X253; ML-Class W166; Sprinter W906; V-Class W639; GLK-Class X204; G-Class W463; S-Class W221.
ОМ629 V8 32 4.0  306–320  700–730 2005–2010 E-Class W211; GL-Class X164; S-Class W221; ML-Class W164.
OM640 4, in-line 16 2.0 82–140 180–300 2004–2012 A-Class W169; B-Class W245.
ОМ646 4, in-line 16 2.2 102–170 235–400 2002–2010 C-Class W203; C-Class W204; CLK-Class C209; E-Class W211; Sprinter W906; V-Class W639.
ОМ647 5, in-line 20 2.7 177 400 2002–2005 E-Class W211.
ОМ613 6, in-line 24 3.2 197 470 1999–2013 E-Class W210; S-Class W220.
ОМ628 V8 32 4.0 250–260 560 1999–2005 E-Class W211; G-Class W463; S-Class W220; ML-Class W163.
OM654 4, in-line 16 2.0 150–245 360‒500 2016 till present C-Class W205; E-Class W213;

Common malfunctions of CDI engines

Malfunctions Engines
Premature wear-out of camshafts, which is determined by the engine construction. OM612.
Often burning of electric wires supplying current to fuel injectors and a boost pressure sensor. OM612, ОМ647.
Burning-out of fire-resistant washers under injectors, which leads to formation of sludge on them. OM612, ОМ647, ОМ613.
Premature breakdown of piezo injectors. OM651.
Misalignment of the crankshaft bearings can occur due to oil pump malfunctions. OM651.
Intake manifold is apt to crack and loss of air-tightness as it is made of plastics. OM651.
Leaks of coolant often occur near the thermostat casing and water pump. OM651.
Oil cooler leaks are often due to unreliability of its gasket. ОМ642.
Due to cracking of the exhaust manifold and ingress of its wear products into the turbine, the latter breaks down prematurely. ОМ642.
The engine is very sensitive to overheating, it results in the appearance of cracks and scoring. ОМ629, ОМ628.
Spilling of fuel by injectors, breakdown of the fuel pump. ОМ629, ОМ628.
The EGR valve gets soiled relatively soon, as well as intake throttle. OM640.
Crankshaft and camshaft position sensors break down often. ОМ646, ОМ647, ОМ613.
Appearance of airlocks in the fuel system due to drying out of quick connectors. ОМ646, ОМ647, ОМ613.

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