A Case Study of Cylinder-Liner Wear in Relation to “Varnish” Films in a Large Long-Stroke Marine Diesel Engine

Results of a case study in which an unusual liner wear pattern is seen to form within the cylinders of a large marine diesel engine are presented. Analysis of the wear patterns and the wear surfaces are also presented which reveal that the maximum wear corresponds to regions on the liner where “varnish” or “lacquer” films appear to build up from decomposition products of the fuel and lubricants employed.

Possible reasons for such wear and film formation are discussed, and compared with frictional and thermal analyses of the ring-liner contacts under operating conditions, with and without the presence of lacquer films.

Preliminary results suggest that such films can act as insulation layers to frictionally generated heat between rings and liner, and if allowed to become thick enough can lead to scuffing.