Many of the company’s current models, including the W213, W222, and W463, are equipped with the 2.9-liter 6-cylinder Mercedes OM656 diesel engine, which has been in production since 2017. This diesel is made of cast iron that has been plasma sprayed with a Nanoslide coating and an aluminum block.
OM603, OM606, OM613, OM648, and OM656 are members of the diesel R6 family.
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
The Camtronic variable valve timing is the primary cause of these issues.
The controlled camshaft, rocker, and drive electromagnets are replaced in the case of a breakdown.
Bad diesel fuel is not tolerated by the CR Bosch CP4 fuel system with piezo injectors.
Additionally, soot rapidly overgrows valves and cylinder head intake channels due to poor fuel.
As usual, environmental bells and whistles like EGR, SCR, and DPF are very problematic.