Deglazing (engine mechanics)

Deglazing is a process by which the surface of an engine cylinder is roughened to create friction between the moving parts and allow engine oil to grip the sides of the cylinder.

Use

In a gasoline or diesel engine, the pistons ride up and down within the engine maintaining a tight seal via the piston rings. Over time, the constant rubbing of the rings against the cylinder wall can wear the wall to a smooth finish. This makes it more difficult for lubricating oil in the engine to adhere properly, which in turn increases friction. Additionally, while breaking in newly installed piston rings, a minute amount of wear must occur between rings and cylinder wall in order to seat the rings properly, and ensure a gas-tight seal. If the cylinder walls are too smooth, this wear will not occur, with the rings "skating" over the polished surface.^[1]

Deglazing involves use of an abrasive to create approximately 45 degree angle crosshatching of tiny grooves in the cylinder wall.^[1] Crosshatching that deviates too far^{[clarification needed]} from 45 degrees can cause either unwanted accumulation of oil or inadequate oil adhesion.^[2]