An experimental study has been carried out to investigate the effect of the level of fuel pump shaft Torsional Vibration (T.V.) on engine noise. The study was carried out on several 6 cylinder automotive DI heavy duty diesel engines. The level of fuel pump T.V. was changed by fitting torsional dampers to the fuel pump shaft. A strong correlation was found between the T.V. level at 12th order of fuel pump rotation and the overall engine noise. Reducing the 12th order of fuel pump T.V. gave significant reductions in both overall and broad-band engine noise.