Does Minor Cylinder Scoring Require an Overhaul?
2 Answers
Minor cylinder scoring requires an overhaul. The main cause of cylinder scoring in cars is insufficient engine oil, which leads to excessively high temperatures during continuous operation. This can cause certain damage to the bearings and pistons, and the high temperatures may also lead to cracking of the cylinder block, severely affecting vehicle performance. Cylinder scoring refers to the 'welding' and damage of the piston, piston rings, and cylinder liner surfaces due to high temperatures. This occurs when the oil film between the piston and cylinder liner is interrupted, leading to dry friction. The intense frictional heat causes microscopic melting and adhesion of the metal, tearing nearby metal particles. To meet gas sealing requirements, the gap between the piston rings and the cylinder liner should be small, which makes lubrication conditions particularly unfavorable. Preventive Measures for Cylinder Scoring: For new engines or those that have undergone major repairs, a proper running-in period is essential. This involves operating under good lubrication conditions, gradually increasing engine speed from low to high and load from small to large, strictly following the running-in procedures before putting the engine into full load operation. Correctly select the clearance between the piston skirt and cylinder liner, as well as the end gap and side gap of the piston rings, according to the specifications in the user manual. Maintain the coolant temperature within the normal range of 70-95°C to prevent engine overheating. Preheating measures should be taken before starting the engine in winter.
I've seen quite a few engine issues, and minor cylinder scoring depends on the specific situation. If there are just small scratches on the cylinder walls and the engine can still start and run normally, it may not necessarily require an immediate overhaul. A simple disassembly for inspection, cylinder honing, or replacing piston rings might suffice—these are low-cost fixes. However, if the damage is deeper, causing oil leaks, blue smoke, or power loss, then it becomes a serious problem, possibly requiring a full engine rebuild. It's best to have a professional technician diagnose it with a compression tester and not delay too long to avoid worsening the damage to the point of scrapping the engine. Regular attention to oil quality and the cooling system, along with scheduled maintenance, can prevent such issues. Safety first—even minor problems should be addressed early.
