The noise and vibration analysis plays a major role for determining the root cause for various faults in a diesel engine. The components of I.C engine produce noise and vibrations due to variation in loads and unbalanced forces which reduce the life of machine. So, it is essential to identify the major sources of vibration and its location and also to reduce the noise to avoid failures in the system. In the present study, experimental modal analysis is carried out for various 3-cylinder engine components to determine resonant frequencies in the system, which have been performed by using roving excitation technique. Then the results of experimental modal analysis are verified by using FEA. The experimental vibration analysis has been carried out at the speed near to the resonance conditions to find out the amplitude of vibrations. A structural borne noise mapping is carried out to know the exact locations of the noise sources. So, based on the results of noise and vibration analysis, structural modifications have been made in the corresponding components of an engine and the improved results have shown that amplitudes of vibration have been reduced by 35 to 40% and the structural borne noise level also reduced by 3 to 4 dB (A).