The importance of oil and particle flow for exhaust valve wear – An experimental study

Oil residue particles have a large impact in protecting the sealing surfaces of heavy duty exhaust valves. To increase the understanding of the mechanism behind this, the wear behavior of exhaust valves subjected to a flow of hot air with controlled amounts of oil particles of three different compositions has been investigated. Air flow without addition of oil was used as a reference. gree and mechanisms of surface damage proved to be sensitive to the test parameters. Residues from the oils containing additives proved to form protective tribofilms, while the oil without additives promoted agglomeration of wear debris on the sealing surfaces. The dry reference showed severe wear with debris scattered over the surfaces.