Mercedes-Benz M103 engine

The Mercedes-Benz M103 is a straight-six petrol engine with a crossflow cylinder head, built from 1984 to 1997. It is a single overhead camshaft design with two valves per cylinder and the cylinders inclined at 15 degrees, and it was offered in 2.6 litre and 3.0 litre forms of 2,599 cc and 2,962 cc. The M104 replaced it from 1989, and over its life it received several updates, among them a change from a heart-shaped to a hemispherical combustion chamber. The M102, the M103 and the 3.0 litre M104 share a piston stroke of 80.25 mm, and the CIS-E injection components of the 2.6 and 3.0 variants are shared for any given model year, so an engine swap from the smaller to the larger version is almost bolt-in.