Engines

Mercedes-Benz M104 engine (1989-98)



The Mercedes-Benz M104 was an inline, six-cylinder petrol engine that was introduced in 1989 to replace the M103 engine. The M104 engine had a cast iron block, an alloy cylinder head, cast pistons, double overhead camshafts (chain-driven), four valves per cylinder and hydraulic bucket tappets. Furthermore, all M104 engines had camshafts adjusters on the intake camshaft. Of these,

  • 104.98 engines advanced the camshaft 34 degrees on activation; and,
  • 104.99 and 104.94 engines advanced the camshaft 32 degrees.

Production of the M104 engine ended in 1998, having been superseded by the M112 engine.

CIS-E, LH-SFI and HFM-SFI injection systems

Initially, the M104 engine had the electronically-controlled CIS-E (Bosch KE-Jetronic) mechanical injection system. The CIS-E system provided knock control and could advance camshaft timing, while ignition was controlled by a separate EZL (‘Elektronische Zündanlage’) i.e. ignition control module. M104 engines with the CIS-E system also had an exhaust camshaft-driven distributor.

From March 1991 to September 1993, the W140 E 300 and S 320 models with the M104.99 engine had Bosch LH-Jetronic (LH 4.1) sequential fuel injection (SFI). Commonly abbreviated as LH-SFI, these engines had exhaust camshaft-driven distributors and a separate EZL. The M104.99 engines were also distinguished by their aluminium intakes and round port cylinder heads.

From 1993, the M104 engines had fully electronic HFM (Hot Film Mass Airflow Sensor) ignition systems with integrated electronic ignition and sequential fuel injection. These HFM-SFI systems used coils that were mounted directly on the spark plugs, replacing the distributor at the front of the engine. Each coil pack provided spark to two spark plugs simultaneously: one connected directly to one plug and the other with a short high tension lead to the next spark plug. As a result, there were three coil wires and three high tension lead wires. The HFM-SFI system had adaptive technology that could compensate for conditions such as engine wear and u Nmeasured intake air to maintain driveability as the engine aged. Furthermore, the HFM-SFI system could retard spark timing to prevent knocking in affected cylinders, unlike EZL which would retard spark timing for all cylinders.

3.6-litre M104.941 AMG engine

The M104.941 AMG engine powered the W124 E 36 AMG, W202 C 36 AMG and W210 E 36 AMG models. With a 92.4 mm stroke and 91.0 mm bore, the 3606 cc displacement of this engine was achieved by increasing the bore of the 2.8-litre block by 2.1 mm and using a modified crankshaft from the 3.5-litre OM603 engine to increase throw by 18.9 mm. Other changes for the M104.941 AMG engine included:

  • Aluminium-forged pistons (with shorter skirts) which were cooled by additional oil jets;
  • A finely balanced crankshaft;
  • A larger intake crossover pipe;
  • A free-flowing exhaust;
  • A unique intake camshaft;
  • Minor cylinder head changes;
  • Modified HFM-SFI engine management system (Motronic M 3.4.2); and,
  • Sodium-cooled exhaust valves.


Code Injection Model Peak power Peak torque Capacity
104.941 HFM-SFI W202 C 280 142 kW at 5500 rpm 270 Nm at 3750 rpm 2799 cc
104.941 HFM-SFI W202 C 36 AMG 206 kW at 5750 rpm 385 Nm at 4000-4750 rpm 3606 cc
104.942 HFM-SFI W124 E 280 142 kW at 5500 rpm 270 Nm at 3750 rpm 2799 cc
104.943 HFM-SFI W140 S 280 142 kW at 5500 rpm 270 Nm at 3750 rpm 2799 cc
104.945 HFM-SFI W210 E 280 142 kW at 5500 rpm 270 Nm at 3750 rpm 2799 cc
104.980 CFI W124 30 E-24 162 kW at 6400 rpm 265 Nm at 4600 rpm 2960 cc
104.980 CFI W124 E 3.4 AMG 200 kW at 6500 rpm 330 Nm at 4500 rpm 3314 cc
104.981 CFI R129 300 SL 24 170 kW at 6300 rpm 272 Nm at 4600rp 2960 cc
104.990 LH-SFI W140 300 SE,
V140 300 SEL
170 kW at 5800 rpm 310 Nm at 4100 rpm 3199 cc
104.991 LH-SFI R129 SL 320 170 kW at 5600 rpm 315 Nm at 3750 rpm 3199 cc
104.992 LH-SFI W124 E 320 162 kW at 5500 rpm 315 Nm at 3850 rpm 3199 cc
104.992 LH-SFI W124 E 36 AMG 200 kW at 5750 rpm 385 Nm at 3750-4500 rpm 3606 cc
104.992 HFM-SFI W124 E 320 162 kW at 5500 rpm 315 Nm at 3850 rpm 3199 cc
104.992 LH-SFI W124 E 36 AMG 200 kW at 5750 rpm 385 Nm at 3750-4500 rpm 3606 cc
104.994 HFM-SFI W140 S 320 170 kW at 5600 rpm 315 Nm at 3750 rpm 3199 cc
104.995 HFM-SFI W210 E 320 162 kW at 5500 rpm 315 Nm at 3850 rpm 3199 cc


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