Marine diesel engine valve gear mechanism diagnostics problems

Marine diesel engines have changed their construction last years because of electronic control implementation in fuelling process. Electronic control implementation could be also important in valve gear mechanism which is main part of the engine gas es exchange system. In this paper problems connected with of valve gear mechanisms operation and diagnostics have been presented. the diagnostic methods and processes which could impact diagnostic process will be shown together with examples from test bed and real vessels. diagnostic methods which based on vibration signals analysis are sensitive on engine load and speed change. separate engine cylinder 's loads generale differences in so called "dynamic valve gear diagrams " which will be shown for some marine engine types. opening and closing of inlet and exhaust valves generale vibration signals in entire engine structure. There are some tools available in signal analysis which gives opportunity to trace changes in signal patterns in real time monitoring systems. special diagnostic method based on vibration signal analysis worked out in the polish naval academy, gives opportunity to change engine maintenance philosophy from scheduled planed maintenance system to condition based maintenance system without fear about real operating engine conditions