The influence of oil refilling strategy on the amount of oil in trunk piston marine diesel engine lubricating system

The issues connected with the amount of lube oil in engine oil system are real problems in marine diesel engines maintenance process. The amount of lube oil in circulation influences its quality and consequently the wear of lubricated parts. That amount still changes and is connected with lubricating oil refilling strategy. The results of simulation carried out for SULZER 8S20U and PIELSTICK 12PC2-5V engines allowed to determine the influence of lubricating oil refilling strategy on the amount of lube oil in circulation. Frequent topping-up at regular intervals can be arranged to maintain the sump working capacity at the chosen percentage of the design maximum (for example 90 per cent), while a significantly delayed topping-up might allow the working capacity to be reduced to as low as about 50 per cent of the maximum. Thus a significantly reduced lubricant amount may have a disadvantageous influence on engine elements wear (i.e. piston rings, cylinder liners) and consequently cause the growth of the engine overhaul costs, although in far perspective, it would be difficult to connect that fact with the amount of oil in circulation. On the other hand in small output trunk piston engines without sump tanks, delayed topping-up and operation with minimum oil level could give some economic and ecological advantages resulting from reduced oil consumption. But in marine conditions (rolling and trim changes) it would be very hazardous for the engine safety operation.