Failure analysis of diesel engine piston in transport utility vehicles

Abstract

Present work deals with the failure analysis of heavy-duty diesel engine piston used in transport utility vehicles. The piston under consideration has failed at 302763 km. Failure mode and effect analysis (FMEA) method is used to identify the engine component having significant contribution in failure. Identification of piston failure has been carried out using FMEA and risk priority number (RPN) for engine components. Experimental analysis of failed piston has been carried out using Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS) and X-Ray Diffraction (XRD) techniques. SEM was employed to speculate the type of failure of piston. Carbon deposition on the piston surface has been observed. EDS of failed piston has also been carried out to identify levels of unnormalized constituent elements contributing to piston failure. From EDS, presence of unnormalized carbon and oxygen is identified and reveal conformability with the failure analysis. Significant percentage of carbon and oxygen at different locations on the piston surface is observed, leading to conclusion of temperature variations inside the cylinder during working. Inferences drawn from piston failure analysis reveal the causes and consequences of failure reasons. The presence of excess carbon on the piston surface indicates the knocking and overheating phenomenon. Remedial measures in addition to periodic maintenance of engine and replacement of worn out gasket to avoid piston failures are presented in this research.