CDI engines are diesel engines that use a common rail direct injection system, which various Mercedes-Benz models are equipped with. The engines came on the market in 1997. They have four, five, six or eight cylinders. They have a chain drive and a turbocharger, usually with an intercooler. The two-stage turbocharger is installed in modern versions; an AdBlue injection system is also used, which reduces harmful emissions in the exhaust gases.
CDI engines consume relatively little fuel, are environmentally friendly, deliver higher power and higher torque. Well-known manufacturers such as Bosch and Delphi supply the injection systems for these engines.
Popular CDI engines
| Index | Number and arrangement of cylinders | Number of valves | Displacement, L | Power, HP | Torque, Nm | Manufacture period | <Mercedes-Benz models |
| OM612 | 5, in-line engine | 20 | 2.7 | 156-170 | 330-400 | 1999-2007 | C Class W203; CLK C209; E class W210; ML W163; G Class W463; Sprinter W901. |
| ОМ651 | 4, in-line engine | 16 | 2.8 and 2.2 | 109‒204 | 250-500 | 2008 to date | A-Class W176; CLS W218; S Class W222; SLK R172; GLA 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 engine | 24 | 3.0 | 286-340 | 600-700 | 2017 to date | CLS C257; S Class W222; E class W213; G-Class W463. |
| ОМ642 | V6 | 24 | 3.0 | 184–265 | 400-620 | 2005 to date | C-Class W204; CLS W219; E class W211; E class W213; CLK C209; CLS W218; E class W212; R Class W251; S Class W222; GL X164; GLC Class X253; ML W166; Sprinter W906; V Class W639; GLK X204; G Class W463; S-Class W221. |
| ОМ629 | V8 | 32 | 4.0 | 306-320 | 700-730 | 2005-2010 | E class W211; GL X164; S Class W221; ML W164. |
| OM640 | 4, in-line engine | 16 | 2.0 | 82-140 | 180-300 | 2004-2012 | A-Class W169; B-Class W245. |
| ОМ646 | 4, in-line engine | 16 | 2.2 | 102-170 | 235-400 | 2002-2010 | C-Class W203; C class W204; CLK C209; E class W211; Sprinter W906; V-Class W639. |
| ОМ647 | 5, in-line engine | 20 | 2.7 | 177 | 400 | 2002-2005 | E Class W211. |
| ОМ613 | 6, in-line engine | 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 W163. |
| OM654 | 4, in-line engine | 16 | 2.0 | 150–245 | 360-500 | 2016 to date | C-Class W205; E-Class W213; |
Frequent defects of CDI-Motoren
| Defects | Engines |
| Premature wear of the Camshafts, which is determined by the engine design. | OM612. |
| Frequent burnout of the electrical wiring that supplies power to the injectors and pressure sensor. | OM612, ОМ647. |
| Burn out of refractory rings under the injectors, causing sludge on them arises. | OM612, ОМ647, ОМ613. |
| Early failure of piezo injectors. | OM651. |
| Crankshaft bearing misalignment can be caused by an oil pump malfunction. | OM651. |
| The intake manifold can crack and Lose airtightness because it is made of plastic. | OM651. |
| Coolant leakage often occurs near the thermostat housing and water pump. | OM651. |
| Oil cooler leaks are usually due to a bad Gasket. | ОМ642. |
| Due to the bursting of the exhaust manifold and the penetration of wear residues into the turbine, the latter fails prematurely. | ОМ642. |
| The engine is extremely prone to overheating, which leads to cracks and breakage. | ОМ629, ОМ628. |
| Spilling fuel through the injectors, fuel pump failure. | ОМ629, ОМ628. |
| The EGR valve is relatively fast contaminated, as well as the intake valve. | OM640. |
| The position sensors for the crankshaft and camshaft often fail. | ОМ646, ОМ647 , ОМ613. |
| The formation of air in the fuel system due to drying out of the connectors. | ОМ646, ОМ647, ОМ613. |