The piston scraping is a common failure to be tightly prevented ,the reason involves:
Unreasonable interval of cylinder sleeve:when the joint interval is overlarge ,the piston is run out during the operation ,it bumps the cylinder sleeve under reciprocating motion and destroy the lubricant film to result in dry rub and scraping;When the joint interval is too small,there is no lubricant film arisen and result in dry rub and scraping of piston skirt.
Abnormal operation of engine cooling system gives rise to over high temperature of engine and too thin or void lubricant escaping from forming lubricant film,then the dry rub results in the scraping of piston skirt.
Improper or bad lubricant fails to form lubricant film or produces easilybroken film to cause by rub abd result in scraping of piston skirt .
Improper mounting ,like reverse mounting of eccentric piston and unclean mounting ,results in the scraping of piston skirt.
Bad or void maintenance of engine filters(air,fuel,and oil filters)makes available for the entrance of strange matters to the cylinder and result in piston scraping.
Overload or improper adjustment of engine result in dieseling of engine and overhiggh temperature in the cylinder and piston-head scraping .
A failure in engine combustion system,invloving bad fuel atomization or improper air-fuel ratio,causes insufficient combustion of engine and produces excess coke to e felled off into the interval between piston and cylinder sleeve .Under seroius circumstance ,it may seize the piston ring and result in piston-head scraping.