Abnormal noises at the piston ring part of diesel generators mainly include metal knocking noise of the piston ring, air leakage noise of the piston ring and abnormal noise caused by deposit excessive carbon.
(1) Metallic knocking noise from the piston rings. After prolonged operation of the engine, the cylinder wall is worn, but the upper part of the cylinder wall that is not in contact with the piston ring almost retains its original geometric shape and size, which creates a step on the cylinder. wall. If an old cylinder seal is used or a new one is too thin, the working piston ring will collide with the cylinder wall step, producing a dull metallic impact noise. If the engine speed increases, the abnormal noise will also increase. Additionally, if the piston ring is broken or the gap between the piston ring and the spokenure of the segment is too large, it will also cause a loud knocking noise.
(2) The sound of air leaking from the piston rings. The elasticity of the piston ring is weakened, the opening space is too large or the openings overlap, and the cylinder wall has grooves, etc., which will cause the piston ring to leak. The sound is a "drinking" or "hissing" sound, and when there is a large air leak, it will make a "hissing" sound. The diagnostic method is to stall the engine when the water temperature exceeds 80°C. At this time, you can inject some fresh, clean engine oil into the cylinder. After cranking the crankshaft for a few revolutions, restart the engine. this time, if the abnormal noise disappears, it will start again soon. If it appears, it can be concluded that the piston ring is leaking.
(3) Abnormal sounds due to excessive carbon deposits. When there is too much deposite carbon, the abnormal noise coming from the cylinder is a high pitched sound. Because the carbon deposit is burned red, the engine exhibits symptoms of premature ignition and is difficult to stall. The formation of carbon deposits on the piston ring is mainly due to lax sealing between the piston ring and the cylinder wall, excessive opening clearance, reverse installation of the piston ring, overlapping of ring holes, etc., resulting in lubricating oil leakage. exhaust upwards and high temperature and high pressure gases exhaust downwards, causing carbon deposits to build up in the piston. The ring part burns, causing carbon deposits to form and even stick to the piston ring, causing the piston ring to lose its elasticity. sealing effect. Generally, this fault can be eliminated after replacing the piston ring with a suitable specification.