What is Engine Cylinder Scoring?
3 Answers
Engine cylinder scoring refers to the phenomenon where the piston and piston rings, during their reciprocating motion within the cylinder, forcibly scrape and create noticeable scratches and grooves on the cylinder wall due to poor lubrication or excessively small clearance between components. Below is an introduction to engine cylinder scoring: 1. Symptoms and sounds of engine cylinder scoring: (1) The engine temperature rises, the RPM becomes unstable, there are signs of stalling, and a "clicking" sound is emitted simultaneously. (2) When the engine experiences cylinder scoring, the main symptoms while driving include weak acceleration and abnormal jerking. 2. Causes of engine cylinder scoring: (1) Overheating engine: Overheating is one of the most common causes of cylinder scoring. When the engine temperature is too high, it disrupts the balance of clearance between the piston, piston rings, and cylinder, leading to cylinder scoring. In severe cases, it may even cause the piston to seize directly within the cylinder. (2) Poor oil lubrication: Generally, engine cylinders are lubricated through splash lubrication, and some engines may also be equipped with dedicated cylinder lubrication injectors. If the oil level is too low, the injector is clogged, or the oil pressure is too low, it is highly likely to result in cylinder scoring. (3) Carbon buildup issue: When carbon deposits accumulated in the cylinder fall into the gap between the piston and cylinder, the reciprocating motion of the piston can forcibly cause scratches and marks on the cylinder wall.
Over the past decade of repairing cars, I've encountered quite a few cases of cylinder scoring. Simply put, it's when the inner walls of the engine cylinders get scratched by the pistons or piston rings. Scratches appear on the cylinder surface, causing the pistons to move less smoothly. The car feels sluggish and breathes heavily when driven, and in severe cases, blue smoke may appear while engine oil consumption increases rapidly. Common causes are usually poor maintenance: insufficient or low-quality engine oil leading to poor lubrication, cooling system issues causing engine overheating, or prolonged high-load operation. Last time, I even saw a case where newly replaced piston rings were installed too tightly, causing cylinder scoring after just a few hundred kilometers. The key is to regularly check engine oil and coolant. Don't wait until the engine needs a major overhaul to regret it—the cost is at least several thousand, and you might as well buy a used engine for that price.
As an old car enthusiast who loves studying engines, cylinder scoring refers to the appearance of grooves on the inner walls of the cylinders. Imagine the piston moving at high speed inside the cylinder, relying solely on a thin layer of oil film for protection. Once the oil film breaks and metal directly rubs against metal, the instantaneous high temperature will carve deep grooves into the cylinder walls. The most common cause is oil-related issues: either insufficient oil quantity, sludge buildup from not changing the oil for tens of thousands of kilometers, or even using counterfeit oil. Secondly, excessively high water temperature is a factor; continuing to drive when the dashboard's coolant temperature warning light is on due to cooling system problems can easily lead to cylinder scoring. Additionally, those who frequently make short trips should be cautious—revving the engine aggressively when the oil hasn't properly lubricated the engine during cold starts can be very damaging. If you notice abnormal engine vibration or a drop in power, get it repaired immediately, or the entire engine could be ruined.
