What are the reasons for cylinder scoring in the four-matching parts?
2 Answers
Four-matching parts cylinder scoring is related to the fit clearance between the piston and cylinder, the quality of the piston itself, and inadequate cleaning of the piston and cylinder. Excessive tight fit clearance between piston and cylinder: If the fit clearance between the piston and cylinder is too small, or if the outer diameter of the cylinder liner is too tight or too loose in the bore, or if the hardness of the cylinder liner is too low, it can cause piston scoring. Poor quality of the piston itself: Inadequate aging treatment, excessive tight fit between the piston pin and piston pin bore causing axial deformation of the piston, or failure to meet roundness requirements for the piston skirt. Inadequate cleaning of piston and cylinder: If the piston and cylinder are not thoroughly cleaned during assembly, leaving sand particles on the piston or its ring grooves, or if the intake passages are not cleaned properly. The former type of scoring usually occurs randomly around the cylinder circumference, while the latter typically occurs on the side opposite the intake valve.
I've been driving for twenty years and have encountered cylinder scoring issues several times, which is when the cylinder walls get scratched or damaged. The most common cause is insufficient lubrication, such as low oil levels or not changing dirty oil on time. Poor-quality oil can also increase friction. Another reason is cooling system failure, where poor heat dissipation causes the engine to overheat, leading to piston expansion and cylinder wall damage. Additionally, damaged or improperly installed piston rings can't handle the pressure. Excessive engine load or frequent speeding can also trigger this issue. I remember one time I neglected to check the dipstick, and the oil leaked out, nearly causing cylinder scoring—it cost a lot to repair. The key to preventing cylinder scoring is regular maintenance: changing oil and filters on schedule, checking coolant levels, avoiding high-temperature engine operation, and driving gently without slamming the accelerator. If you notice symptoms like weak acceleration, increased noise, or higher fuel consumption, stop and inspect the car immediately to prevent further damage.
