Predicted and Actual Effect of Cylinder Liner Wear on the Blowby in a Truck Diesel Engine

The paper investigates the cylinder liner wear and its influence on the engine blowby. The course of cylinder liner wear was established on the basis of investigation, which was carried out using 5 diesel engines during long-lasting operation in motor trucks. Cylinder diameters were periodically measured in two perpendicular planes at four depths of the liner. During service of the trucks the blowby rate was also measured, which enabled evaluating of the changes of the blowby rate as a function of truck mileage. The effect of cylinder wear on the blowby was also predicted with the use of a mathematical model of a gas flow through the ring pack. The results of the numerical simulations and empirical investigations are compared and discussed.