Turbochargers caused significant number of marine diesel engines malfunctions especially when engine is fueled by heavy fuel oil. Vibro-acoustic diagnostic methods which could be used on marine diesel engines with turbochargers are presented in the paper. Vibration signals generated by turbochargers need different signal processing methods to be effective and faultless in turbochargers diagnostics. Diagnostic methods which based on vibration signals analysis are sensitive on engine load and speed changes. Some results of turbocharger tests which were carried out in the Polish Naval Academy Technical Institute of Ship Maintenance laboratory are presented in the paper with special attention given to the practical aspects in processing the vibration signal and diagnostic effectiveness.