The 2.9-liter 6-cylinder Mercedes OM656 diesel engine has been produced since 2017 and is installed on many modern models of the concern, such as the W213, W222 or W463. This diesel has an aluminum block and plasma sprayed cast iron with Nanoslide coating.
The diesel R6-family includes: OM603, OM606, OM613, OM648, OM656.
Specifications
| Production years | since 2017 |
| Displacement, cc | 2927 |
| Fuel system | Common Rail |
| Power output, hp | 272 – 286 (OM656 D29 R SCR or 350 d) 330 – 340 (OM 656 D29 SCR or 400 d) |
| Torque output, Nm | 600 (OM656 D29 R SCR or 350 d) 700 (OM 656 D29 SCR or 400 d) |
| Cylinder block | aluminum R6 |
| Block head | aluminum 24v |
| Cylinder bore, mm | 82 |
| Piston stroke, mm | 92.4 |
| Compression ratio | 15.5 |
| Features | AdBlue |
| Hydraulic lifters | yes |
| Timing drive | chain |
| Phase regulator | Camtronic |
| Turbocharging | BorgWarner R2S |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 8.5 |
| Fuel type | diesel |
| Euro standards | EURO 6 |
| Fuel consumption, L/100 km (for Mercedes-Benz S 400 d 2018) — city — highway — combined |
6.8 4.8 5.6 |
| Engine lifespan, km | ~250 000 |
The engine was installed on:
- Mercedes CLS-Class C257 since 2018;
- Mercedes GLC-Class X253 since 2019;
- Mercedes GLE-Class W187 since 2018;
- Mercedes GLS-Class X167 since 2019;
- Mercedes G-Class W463 since 2019;
- Mercedes E-Class W213 since 2018;
- Mercedes S-Class W222 in 2017 – 2020; S-Class W223 since 2020.
Disadvantages of the OM656 engine
- Most of the problems here are related to the Camtronic variable valve timing.
- In the event of a breakdown, the drive electromagnets, controlled camshaft and rocker change.
- The CR Bosch CP4 fuel system with piezo injectors does not tolerate bad diesel fuel.
- Also, from bad fuel, valves and cylinder head intake channels are quickly overgrown with soot.
- Environmental bells and whistles like EGR, SCR and DPF, as always, cause a lot of trouble.
