Common Faults Of Gasoline Engines Of Outboard Motors: Cylinder Scuffing

The gasoline engine is one of the important components of the outboard engine. During its use, various failures will occur, and cylinder scuffing is one of them. Regarding this kind of failure, the relevant person from the outboard engine manufacturer said this :
Cylinder scuffing is the phenomenon of upper and lower scratch marks in the area where the inner surface of the cylinder liner is in contact with the reciprocating motion of the piston. Generally, the cylinder scuffing phenomenon often occurs during the break-in period after the engine overhaul; some also occur during normal operation. . When the cylinder is pulled, there are generally mild trace-like pull marks on the inner surface of the cylinder liner, and severe sheet-like pull marks rarely appear. Most of the strained parts are on the two sides of the cylinder liner perpendicular to the axis of the piston pin. Most of the damaged parts of the cylinder are cylinder liner (inner surface), piston (outer surface) and piston ring (outer contact surface).
The basic reason for cylinder damage is that local dry friction occurs between the cylinder liner and the piston friction ring. As a result, the asperities on the metal surface contact each other. Under the action of high load, the asperities deform, and during mutual motion, a large amount of frictional heat is generated, which melts and fuses the asperities, and then pulls them apart, forming scraping marks and generating wear debris. Metal wear debris is embedded on the surface of the piston (there is no lubricating oil to wash them away), scratching the cylinder wall.
There are many factors that affect cylinder pulling, and the situation is more complicated. It is mainly related to the working conditions of the engine (temperature and load), the cooperation between the piston and the cylinder liner, and the matching materials. However, the running-in condition of the engine during the running-in period is the key to affecting cylinder scuffing.