Study of the reliability of internal combustion engines by application of a Weibull model in bands

The performance of 1,6 l four-valve Otto cycle engines is examined in this paper from the point of view of excessive consumption of lubricating oil. Three failure bands were recognized, at low, medium, and high distance traveled, each one obtained from a sample of 15 vehicles. A “Weibull model in bands” was applied; we obtained a satisfactory result from the point of view of reliability and applied the method to several types of motor vehicle. FMEA analysis of a sample permitted identification of the principal causes of unevenness in cylinder surfaces and an evaluation of the methods of machining required to correct this unevenness. Finishing of cylinders with a flexible smoothing tool is a low-cost technique for restoring vehicles to a suitable reliability level.