Diesel engine is critical equipment because its failure has high consequences on cost. Therefore, developing a sensitive condition monitoring system capable of detecting a fault in its early stages before break-down happens is very essential. In combustion chamber the pressure carries very useful information on combustion process. However flame front pressure sensors are very expensive and intrusive in nature, which make this another impractical to use.On the other hand engine body vibration signatures are rich in information about its operating parameters and physical condition and could be measured by attaching an accelerometer to the engine block. Study is focused on ways to extract useful information about the diesel engine operating conditions and health from the vibration signals in untreated laboratory environment. The diesel engine vibration sources were reviewed, time domain method and frequency domain method was applied to the engine body vibration to extract the useful information and thus determine the condition of the diesel engine under different speeds and loads.