The surface temperature of cylinder liner is one of the factors which affect to the lubrication between cylinder liner and piston rings. Although many works has been conducted with experimental apparatus, few experiments studied with practical diesel engines in pre-running period.
In the pre-running period, engine frequently have metal contacts of cylinder liner and piston rings. It is think that the rise of temperature by metal contacts affect to the state of liner-ring lubrication. So the cylinder liner temperature of a marine diesel engine was measured in pre-running period.
From experimental results, it was found that the liner temperature of few measurement points changed irregularly at the first glance, but almost were arranged statistically in few forms, and maximum temperature and mode-value ratein the form were more important than mean temperature to estimate the state of the liner-rings lubrication.

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The carbonaceous particulate or soot emission from diesel engines has become one of serious environmental problems in the world. There is no regulation on particulate emission from marine diesel engine at present. In the present report, experimental investigation was conducted with a two-stroke marine diesel engine to know the characteristics of particulate emission. Concentration of particulate emission was measured by three kinds of method, such as direct sampling method, partial-flow dilution tunnel method and Bosch type smoke meter method. The effects of engine load ratio and cylinder oil feed rate have been examined. The experimental results show that the particulate concentration measured by the dilution tunnel method increases with an increase in cylinder oil feed rate. The data points obtained by the direct sampling method and the smoke meter are somewhat scattered and the general tendency is not evident within the limits of this experiment.

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Thermal sprayed coatings are applied to lubricated sliding surfaces of engine components recently.
Small size peelings were observed on the ceramic coated test pieces tested with a pin on disk wear tester. The mechanism of peelings was investigated.
A test in which a ball was rolled on the coated surface was carried out. The test was considered to be appropriate for evaluating the peeling property of coatings for the correlation to wear test results. The rolling test results show that the peeling was not affected by the change of temperature but was strongly affected by the existence of lubricating oil. The same tendency was also observed in a cyclic loading test. Cross sectional view of tested surface shows a Hertz crack connected to a horizontal crack. Peelings can be caused by the formation of these cracks. Crack propagation is accelerated by the existence of lubricating oil. It is considered that the oil enclosed in the crack is pressurized by load and it expands the crack.

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