The Mercedes-Benz OM629 is a 4.0 litres (3,996 cc) diesel-fuelled, 4-stroke, compression-ignition internal combustion 75° 32-valve V8 engine used in the 2000s.

[1] The consequence of this specific angle is free inertial forces of the first order.

To ensure even firing intervals the crankshaft uses split crank pins.

The engine uses dual overhead camshafts on each bank (‘quad-cam’) with four valves per cylinder, operated by hydraulic tappets.

Compared to the OM628, the OM629 engine has an improved common-rail system,[2] and higher boost from the turbochargers.