Reliability has always been an important aspect in the assessment of industrial products and/or equipments. Good product design is of course essential for products with high reliability. However, no matter how good the product design is, products deteriorate over time since they are operating under certain stress or load in the real environment, often involving randomness. Maintenance has, thus, been introduced as an efficient way to assure a satisfactory level of reliability during the useful life of a physical asset. The earliest maintenance technique is basically breakdown maintenance (also called unplanned maintenance, or run-to-failure maintenance), which takes place only at breakdowns. A later maintenance technique is time-based preventive maintenance (also called planned maintenance), which sets a periodic interval to perform preventive maintenance regardless of the health status of a physical asset. The vehicle component is judged to be safe depending on its reliability. Consequently, there is a general attention to establish approach by which the failure risk has to be known. To achieve this objective, the present work introduces an approach to establish the vehicle engine risk assessment using the excess air escaped inside the engine crankcase. The results indicate that the excess scalped air mass flow rate corresponding to the failure rate values computed based on the Weibull distribution with assured reliability can be considered to be guide for maintenance regime.