The decoupling, i. e the elastic support of the engine block in an external housing (skeleton engine), was applied to a watercooled 1.5 1 4-cylinder gasoline production engine. Rubber elements used for the elastic support caused low frequency vibration problems. The rigid mounting of the supporting brackets in the external housing, however, ensured the necessary stiffness without incurring significant losses in noise reduction. The noise above 500 Hz was considerably reduced to the expense of some increase in low frequency noise. The noise emissions of the skeleton engine are similar to those achieved by total engine enclosures which were developed in earlier projects.