The object of the invention is a device for cleaning the core engine of a jet engine, having a supply unit, which provides the cleaning medium, a nozzle unit, which is configured for feeding the cleaning medium into the core engine, and a line connection (10) between the supply unit and the nozzle unit. The invention provides that the nozzle unit has a means for the rotationally fixed connection to the fan shaft of the jet engine, and that a rotary coupling (5) is provided between the nozzle unit and the line connection (10). The object of the invention is further an arrangement of such a device and a turbo fan jet engine, and a method for cleaning the core engine of a jet engine using the device.