A tunnel-type machine to wash objects comprises a containing structure which internally delimits a work volume and is provided with at least an entrance door to feed the objects in a loading direction. The work volume comprises at least two processing chambers contiguous in the loading direction, a single separation door is provided between the two processing chambers, and is mobile through a passage aperture of the containing structure. At least a front packing is provided between the two processing chambers, and at least an upper packing is provided at the passage aperture, and the separation door is configured to contact, in a closed and separated position of the two chambers, both the front packing and the upper packing.