A combustion engine includes a cylinder head including a controllable engine valve configured to open/close a combustion chamber in the combustion engine, a valve actuator operatively connected with and configured to displace the engine valve, and a closed pressure fluid circuit, wherein the valve actuator is arranged in the closed pressure fluid circuit. The combustion engine includes a cylinder head chamber that is included in the closed pressure fluid circuit and that is delimited by the cylinder head and a cylinder head mantle, by the valve actuator including a pneumatic pressure fluid circuit with an outlet opening that is in fluid communication with the cylinder head chamber, and by the cylinder head chamber including a hydraulic liquid drainage valve, wherein a drainage conduit stretches from the hydraulic liquid drainage valve to a hydraulic liquid vessel of the combustion engine for draining hydraulic liquid accumulated in the cylinder head chamber.