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System contamination caused by contaminates or small particles built-in, self-generated, or inhaled from environment presents severe problems. The problems include but are not limited to the malfunctioning of valves, pumps, seals and injectors or lock-up of these components; increased wear of bearings, piston rings, and other friction components; and degradated machine performance. In general, system contamination changes a deterministic system into a stochastic system and shortens machinery service life. In this paper, these contamination problems are discussed in categories and associated analysis, testing and computer modeling methodologies are also discussed.

Radioactive tracer technology is an important tool for measuring component wear on a real-time basis and is especially useful in measuring engine wear as it is affected by combustion system operation and lubricant performance. Combustion system operation including the use of early and/or late fuel injection and EGR for emissions control can have a profound effect on aftertreatment contamination and engine reliability due to wear. Liner wear caused by localized fuel impingement can lead to excessive oil consumption and fuel dilution can cause excessive wear of rings and bearings. To facilitate typical wear measurement, the engine's compression rings and connecting rod bearings are initially exposed to thermal neutrons in a nuclear reactor to produce artificial radioisotopes that are separately characteristic of the ring and bearing wear surfaces.

Systems for controlling automotive exhaust particulates, especially lead particulates, are discussed and a suitable method for determining automotive particulate emission levels during on-the-road vehicle operation is presented. Data is presented for a large number of vehicles. The evaluation system is suited for use with a large variety of vehicles during all modes of vehicle operation. A total emissions control system, capable of meeting the strict 1978 statutory gaseous emissions levels with virtually zero particulate emissions, is also discussed. This emissions control system is compatible with leaded and unleaded fuels. The economic implications of lead additive restriction, as a means of reducing lead airborne particulates, are briefly considered. It is concluded that the reduction of airborne lead, by trapping it in the exhaust system, is more cost effective and energy conservative than is reduction by regulation of the fuel supply.