In the article further continued investigation mathematical model of the carters side walls vibrations of tractors air cooled engines. There is shown, that greatest amplitudes of vibrations are in the middle of the bottom of carter's side wall. By introducing additional connections it is possible significantly decrease the amplitude of the vibrations. Experimentally established the stiffening of the carter bottom in two places by the special stips the power of the side walls noise decreased by 2 dBA.