To improve the quality of air, regulations for emissions from diesel engines have become stringent over the decade. International maritime organization (IMO) and the United Nations for climate change have joined hands to ensure that the environment is free from air pollution. This calls for engine designers to come up with more environmentally friendly engines. Meanwhile, for the already existing engines, proper repair, and maintenance of engine components is very important to improve the engine efficiency, reduce emissions and improve durability. In this study, we analyze the effect of the turbocharger overhaul on the engine performance and the emission formation both experimentally and numerically. Experiments and combustion simulations were conducted before and after the turbocharger overhaul. As a result, higher engine SFOC was evidenced at all loads before the turbocharger overhaul. After the turbocharger overhaul, the in-cylinder pressure was increased by 2.165%, 1.627%, 2.91% and 0.231% at 75%, 50%, 25% and idle load, respectively. Similarly, SFOC was reduced by 2.39%, 3.04% and 3.02% at 75%, 50% and 25% load, respectively. The exhaust gas temperatures and emissions were slightly reduced after the turbocharger overhaul. Although the emission reduction as a result of the turbocharger overhaul does not achieve the emission regulation limits, combination with other emission reduction devices and technologies can reduce emissions from diesel engines significantly.