What happens to a piston when it is out of round?

When a piston is out of round, it refers to a condition where the piston does not maintain a uniform circular shape throughout its entire circumference. This irregularity can lead to uneven contact against the cylinder walls. As a result, an out-of-round piston may not fit properly in the cylinder, causing additional friction and movement. This misalignment leads to increased wear on both the piston and the cylinder bore because the surfaces are not able to slide against each other smoothly.

Furthermore, the abnormal motion of the piston can create inconsistencies in combustion, increase the risk of piston slap, and can result in a loss of power due to inefficient movement. Thus, the increased wear caused by an out-of-round piston can significantly shorten the lifespan of engine components and lead to more frequent repairs and maintenance needs. This understanding emphasizes the importance of proper piston shape and fit to ensure optimal engine performance and longevity.