A numerical model of the piston skirt taking into account its lateral, reciprocating and rotatory motion has been presented in order to investigate the lateral motion of piston skirt assembly and resulting vibrations induced as a result of these motions in the engine block. Various parameters of modal analysis were obtained using mobility analysis. The presented methodology was validated by data obtained from a diesel engine test set up. The predicted results matched well with those of measured data, hence validating the presented scheme.