Tuning method for high-speed marine diesel engine MB820 Type

Checking and tuning of the fuel injection valves opening pressures, fuel valves timing and exhaust or inlet valves clearances is a common practice in high-speed marine diesel engines maintenance. Cost lowering tendency in engine maintenance schedules and unmanned vessel's propulsion plants need new approach to these old and reliable procedures. Conventional maintenance methods for engine valve gear mechanism depend on valve clearances checks between valve stem and rocker arm and valve timing diagram checks on crankshaft flywheel. But how to observe valves' timing diagram on working engine and what is the difference between static and dynamic valves timing diagram and in the end how engine load and speed changes disturb observed parameters? Answers for these and other questions for high-speed marine diesel engines MB820 type are given in this paper. Dynamic valve gear timing diagrams are indispensable to perform an accurate engine tuning. A new original diagnostic and tuning method for high-speed marine diesel engine MB820 is presented in the paper. In the principle this method based on measurements of: internal cylinder pressure curves and on vibration signals. Typical diagnostic methods which based on vibration signals analysis are sensitive to engine load and speed changes. Researches presented in this paper were focused on the possibilities and differences of the dynamic timing diagram assessing at engine rated load and when idling.