Liner scuffing is a serious risk that might lead to engine repairs and prolonged downtime. If understanding the causes, we can take preventive measures to reduce the risk of scuffing and ensure optimal engine performance, reliability, and endurance.
Liner scuffing is a form of micro welding or direct contact between the cylinder liner and piston rings or piston, is extreme adhesive wear between lubricated surfaces – liner and piston.
This occurs when the lubricant film breaks down or fails due to various reasons, leading to noticeable friction wear that can be identified by observing a dragged appearance on the liner surface. Liner scuffing can lead to significant damage to the engine, resulting in reduced efficiency, increased maintenance costs, and potentially engine failure.
Figure 1 Adhesive wear
Figure 2 liner scuffing
Liner scuffing can occur due to several reasons, including:
Insufficient lubrication: Insufficient lubrication of the cylinder liner can result in increased friction between the piston rings and the cylinder liner––leading to scuffing, this may lead by low oil level in oil sump, bigger allowed bearing / journal clearance and etc.
Abrasive wear: Is caused by abrasive particles called cat fines, in the fuel oil. Fuels today and especially Low Sulphur Fuels contain abrasive particles in form of cat fines causing a rough scratched cylinder liner and piston rings that prevent the hydrodynamic oil film from working efficiently.
Figure 3 Abrasive wear
Deposit build-up: Build-up of excess deposits on piston crown top land prevents a protective oil film layer to form on the liner surface. Furthermore, deposits can be situated in the piston ring clearance, preventing the rings from moving freely. Typical causes are over lubrication or excessive additives transform into deposits on the piston land and rings during combustion.
Figure 4 Carbon deposit on piston crown
