646.986 engine — Mercedes-Benz 2.1 CDI (2.1L)
2.1L · 150 hp
Engine overview
Vehicles with this engine
Factory specifications
Values from the manufacturer documentation for this engine.
Engine (general)
| Engine code | 646.986 (OM646 DE 22 LA) |
| Capacity | 2148 cc |
| Normal | 29.0 - 35.0 bar |
| Minimum | 18.0 bar |
| Differential limit between cylinders | < 3.0 bar |
| Max. compression loss between cylinders | 25 % |
| Oil pressure | > 0.7 bar/rpm |
| Oil pressure | > 2.5 / 3200 bar/rpm |
Engine (diesel)
| System (make and type) | CDI 3 |
| Number of cylinders | 4 |
| Injector firing order | 1 - 3 - 4 - 2 |
| High-pressure pump: | Bosch |
| Pressure | < 1600 bar |
| Pressure | 4.0 - 4.5 bar |
| Injector pressure | 1600 bar |
| Coolant temperature during test | 80 °C |
Cooling system
| Cap pressure | 1.4 ± 0.1 bar |
Electrical
| Alternator | 90 / 180 / 200 / 220 A |
Capacities
| Engine sump, incl. filter | 11.0 l |
| Manual transmission | 711.651 |
| Gearbox refill | 1.5 l |
| Gearbox refill | 1.75 l |
| Gearbox refill | 2.5 l |
| Manual transmission | 711.660 |
| Gearbox refill | 2.0 l |
| Gearbox refill | 3.25 l |
| Automatic transmission | 722.683/684/685 |
| Initial filling | 7.1 l |
| Differential, rear | 741.412/413/414/416 l |
| Gearbox refill | 2.6 l |
| Differential, rear | 741.415 l |
| Gearbox refill | 1.6 l |
| Differential, rear | 741.417 l |
| Transfer box | 1.0 l |
| Differential, 4WD front | 0.65 l |
| Differential, 4WD front after overhaul | 0.85 l |
| Cooling system | 9.5 l |
| Air-conditioner refrigerant | 1000 (H08) 1190 (HH7) 800 (HH9) g |
| Air-conditioner compressor oil | 160 (H08) 190 (HH7, HH9) ml |
Torque settings
| Cylinder head (M12 bolts) — Stage 1 | 15 Nm |
| Cylinder head (M12 bolts) — Stage 2 | 60 Nm |
| Cylinder head (M12 bolts) — Stage 3 | 90 ° |
| Cylinder head (M12 bolts) — Stage 4 | 90 ° |
| Cylinder head (M8 bolts) — Stage 1 | 20 Nm |
| Glow plugs | 19 Nm |
| Main bearing cap — Stage 1 | 50 Nm |
| Main bearing cap — Stage 2 | 95 ° |
| Big-end bearing cap — Stage 1 | 5 Nm |
| Big-end bearing cap — Stage 2 | 25 Nm |
| Big-end bearing cap — Stage 3 | 90 ° |
| Oil plug | 30 Nm |
| Manual transmission drain plug | 60 Nm |
| Manual transmission filler plug | 50 Nm |
| Transfer box drain plug | 35 Nm |
| Transfer box filler plug | 35 Nm |
| Differential drain plug | 50 Nm |
| Wheel bolts | 240 Nm |
| Wheel bolts | 180 Nm |
| Wheel nuts | 180 Nm |
Workshop procedures for this engine
Step-by-step procedures from the workshop database.
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TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
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The story behind TorqFix →Workshop data on this page last updated 22 Aug 2026.