Embodiments for mass balancing an engine are provided. In one example, an internal combustion engine having at least one cylinder which is associated with a crank drive comprises at least one mechanically driven balancing unit for balancing the mass forces, the balancing unit including at least one balancing weight which serves as an unbalance by initially rotating a first mass about a rotational axis relative to a second mass when the balancing unit is operational, and an interrupter unit to disconnect the at least one balancing unit from the mechanical drive in a switched off state and connect it to the mechanical drive in a switched on state.