103.943 engine — Mercedes-Benz 2.6 (2.6L)
2.6L · 160-166 hp
Engine overview
Vehicles with this engine
Factory specifications
Values from the manufacturer documentation for this engine.
Engine (general)
| Engine code | 103.943 |
| Capacity | 2597 cc |
| Idle speed | 650 - 750 rpm |
| Inlet | 0.10 - 0.20 mm |
| Exhaust | 0.25 - 0.35 mm |
| Normal | 10.0 - 12.0 bar |
| Minimum | 8.5 bar |
| Oil pressure | 3.0 / 3000 bar/rpm |
| Capacity | 2599 cc |
| Idle speed | 600 - 800 rpm |
| Normal | 9 - 12 bar |
| Minimum | 7.5 bar |
| Oil pressure | 3/3000 bar/rpm |
Engine (petrol)
| Fuel system (make and type) | Bosch KE-Jetronic |
| Number of cylinders | 6 |
| Firing order | 1-5-3-6-2-4 |
| Timing stroboscopic (before TDC) | 19 - 23 / 3200 °/rpm |
| Timing stroboscopic (vacuum hose connected) | 40 - 44 / 3200 °/rpm |
| Ignition coil resistance, primary | 0.3 - 0.6 ohms |
| Ignition coil resistance, secondary | 8000 - 13000 ohms |
| Spark plugs (make and type) | Beru 14 K 7 DUO Bosch H 7 DCO |
| Spark plug gap | 0.8 mm |
| Injection pressure/system pressure | 5.3 - 5.5 bar |
| CO exhaust gas | < 0.5 % |
| CO2 | 13.0 - 16.0 % |
| HC | 300 ppm |
| O2 | 0.5 - 2.0 % |
| Lambda | 0.97 - 1.03 |
| Lambda change (Delta Lambda) | 0.02 |
| Oil temperature during test | 60 °C |
| Fast-idle speed | 2200 - 2800 rpm |
| CO at fast-idle speed | < 0.3 % |
| Closed-loop test at: | 500 - 1100 rpm |
| Idle speed adjustment screw | A |
| CO adjustment screw | B |
| Timing stroboscopic (before TDC) | 7 - 11 °/rpm |
| Spark plugs (make and type) | Beru 14K8DUO Bosch H8DCO |
| CO exhaust gas | 1.0 ± 0.5 % |
| Catalytic converter | < 0.5 % |
| Catalytic converter | 14.5 - 16.0 % |
| Catalytic converter | 100 |
| Catalytic converter | 0.1 - 0.5 % |
| CO at fast-idle speed | 0.3 % |
| Fast-idle speed | 2200-2800 rpm |
| Closed-loop test at: | 500-1100 rpm |
| Alternative method (Germany only) | Nr. G2 |
| Alternative method (Germany only) | Nr. 1b, ± 10 |
Cooling system
| Cap pressure | 120: 1.2 ± 0.1 140: 1.4 ± 0.1 bar |
| Thermostat opens at | 87 ± 2 °C |
| Cap pressure | 1.3 - 1.5 bar |
| Thermostat opens at | 85 - 89 °C |
Electrical
| Battery | 62 Ah |
| Alternator | 80 A |
| Battery | 55 Ah |
| Alternator | 70 A |
Capacities
| Engine sump, incl. filter | 6.0 l |
| Gearbox refill | 1.5 l |
| Differential | 1.0 l |
| Gearbox refill | 6.2 l |
| Cooling system | 8.0 l |
Torque settings
| Cylinder head bolts — Stage 1 | 70 Nm |
| Cylinder head bolts — Stage 2 | 90 ° |
| Cylinder head bolts — Stage 3 | 90 ° |
| Spark plugs | 20 Nm |
| Wheel nuts | 110 Nm |
| Rear hub | 30 Nm |
| Rear hub | 90 Nm |
Workshop procedures for this engine
Step-by-step procedures from the workshop database.
Got a 103.943 problem? Ask for free.
Describe the symptoms — TorqFix replies with a diagnosis cited from verified workshop data.
Get free diagnosis →Who makes these pages, and how
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.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 22 Aug 2026.