The Mercedes OM628 engine is an 8-cylinder diesel engine in a V-configuration with direct injection and turbocharger, developed and produced by Daimler-Benz for use in Mercedes-Benz mid-range passenger cars. OM 628 debuted in the summer of 2000 in the Mercedes S 400 CDI S-Class (220 series).
The diesel V8-family includes: OM628, OM629.
Also used in the E-Class (W 211) and in the G-Class and M-Class SUVs (W 163). The OM628 engine was Daimler-Chrysler’s answer to the rival’s Audi A8 and BMW 740d with their 8-cylinder diesels. The engine block and cylinder heads are made of aluminum alloy by sand casting.
Specifications
| Production years | 1999-2005 |
| Displacement, cc | 3996 |
| Fuel system | Common Rail |
| Power output, hp | 250 – 260 |
| Torque output, Nm | 560 |
| Cylinder block | aluminum V8 |
| Block head | aluminum 32v |
| Cylinder bore, mm | 86 |
| Piston stroke, mm | 86 |
| Compression ratio | 18.5 |
| Features | intercooler |
| Hydraulic lifters | yes |
| Timing drive | chain |
| Phase regulator | no |
| Turbocharging | GT1749V |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 10.5 |
| Fuel type | diesel |
| Euro standards | EURO 4 |
| Fuel consumption, L/100 km (for Mercedes ML 400 CDI 2003) — city — highway — combined |
14.7 8.8 10.9 |
| Engine lifespan, km | ~300 000 |
| Weight, kg | 275 |
The engine was installed on:
- Mercedes E-Class W211 in 2002 – 2005;
- Mercedes G-Class W463 in 2001 – 2005;
- Mercedes ML-Class W163 in 2001 – 2005;
- Mercedes S-Class W220 in 1999 – 2005.
Disadvantages of the OM628 engine
The OM628 engine is famous for its many problems and the difficulty in fixing them:
- the main troubles are caused by constantly pouring injectors, as well as fuel injection pump failures;
- the motor tends to coke very quickly, especially the EGR;
- prolonged overheating can lead to scuffing in the cylinder liners;
- on runs of 150+ thousand km, many owners have encountered cylinder head cracks.
