A piston ring is an expandable split ring used to provide a seal between the piston an the cylinder wall. The pressurized gases travel through the gap between the cylinder wall and the piston and into the piston ring groove. Combustion gas pressure forces the piston ring against the cylinder wall to form a seal.Click to see full answer. Regarding this, what causes piston rings to fail?The cause of failure would be the ring not being sufficiently compressed and was damaged during installation. Rings not installed correctly allow a combustion path to the crankcase causing high crankcase pressure “blow by” and loss of power.Also, how are piston rings made? Piston rings of marine engines are made with the help of pot casting method. In this method a short cylinder of oval cross section is made and the piston rings are then cut and machined from the cylinder. With this method a homogeneous and balanced casting is formed around the entire circumference of the ring. In respect to this, what are the symptoms of bad piston rings? Piston rings eventually start to wear and the seal between the piston and cylinder is no longer air tight. As a result, oil makes its way from the crankcase past the piston and into the firing chamber. Symptoms of this are white smoke coming from the tailpipe and a drop in engine oil level.How do I know if I need new piston rings? Signs your piston rings need replacing Excessive smoke. If the smoke coming out of your engine is grey in colour and particularly thick, then it could mean your piston rings need replacing. Using more oil than usual. If your oil consumption seems to have increased all of a sudden, then old piston rings could be the culprit. Lacking power. Decreased performance.