Depending on the actual operating situation and the composition of the fuels used for driving the internal combustion engine, contamination of the moving blades, of the guide device and of the turbine casing parts occurs sooner or later in the exhaust gas turbine. According to the invention, a small quantity of cleaning fluid is fed continuously or cyclically into the exhaust gas flow of an exhaust gas turbine and is directed onto the components to be cleaned. The small quantity of cleaning fluid can be fed in with unchanged operation of the internal combustion engine, such that the exhaust gas turbine can be cleaned or kept clean within the entire operating range of the internal combustion engine. Fluctuations in the power output of the internal combustion engine on account of requisite cleaning of the exhaust gas turbine therefore do not occur. Furthermore, the formation of thermostress cracks in the critical turbine casing parts is largely avoided.