A study has been carried out to investigate the influence of soot contaminated automotive lubricants in the wear process of a simulated engine valve train contact. Previous research on this topic has been mainly performed from a chemical point of view in fundamental studies, with insufficient relevance to real engine conditions i.e. load and geometry. This study investigates the conditions under which wear occurs through specimen testing. The objective of the work was to understand the wear mechanisms that occur within the contaminated contact zone, to help in future development of a predictive wear model to assist in the valvetrain design process.The effects of soot in lubricants have been tested using a reciprocating test-rig specifically designed for this application, where a steel disc is held in a bath of oil and a steel ball (replicating a valve train contact) is attached to a reciprocating arm. The materials, contact geometry and loading conditions are all related to specific conditions experienced within an engine's valve-train. The testing was carried out under various contact conditions, using carbon black as a soot simulant. Wear measurements were taken during the tests and wear scar morphology was studied.The results have revealed how varying lubrication conditions changes the wear rate of engine components and determines the wear mechanism that dominates for specific situations. Draft copy of paper submitted to IMechE, Part J, Journal of Tribology KEYWORDS INTRODUCTIONAs internal combustion engine technology advances due to demands for improved fuel economy and performance, and lower oil consumption the many component contacts within an engine are operating under higher loads with thinner oil films to provide lubrication. This combined with the desire for increased service and oil drain intervals means that more wear problems are arising, which engine manufacturers are having to address as a matter of urgency so that their engines can meet all these requirements. There is currently a lack of wear models for lubricated engine components, leaving the understanding of the problem at a basic level that cannot be applied by engine designers. As part of a long term approach, wear models and design tools for engine components are required to increase understanding and reduce wear. The work detailed in this paper is part of a wider project to develop such models and tools for application by industry.

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