The main causes of cylinder pulling are as follows:
(1) The fit clearance between piston and cylinder is too small.
(2) Poor lubrication between piston and cylinder, improper selection of engine oil.
(3) The piston ring is broken, seized on the piston, or the piston pin circlip is broken or falls off.
(4) The piston and piston ring are tilted to one side and pressed tightly against the cylinder wall.
(5) The engine runs at high speed or under heavy load for a long time without running in after overhaul.
(6) Poor engine cooling, cooling system failure.
(7) The engine oil is not clean and contains a lot of impurities.
(8) Long term overload and low speed driving.
(9) The cylinder produced by informal manufacturers has low hardness and poor quality.
(10) The air filter fails, and air impurities are mixed into the combustion chamber and fall into the cylinder wall.
There are four factors to investigate the causes of engine oil when troubleshooting mechanical faults:
(1) Improper selection of oil viscosity
The vehicle has been used for a long time and the cylinder is worn to a certain extent. The engine oil with slightly higher basic viscosity should be selected, but the oil with too high viscosity should not be selected. It is possible that the lubrication failure of cylinder pulling may be caused by the difficulty of reaching the cylinder wall.
(2) Improper oil grade
Different grades of engine oils contain different additives and have different extreme pressure and wear resistance, which can not be compensated by high viscosity oil alone. Using low-grade oil may cause cylinder pulling due to insufficient wear resistance.
(3) Excessive oil impurities
After using the engine oil for a period of time, the engine oil will deteriorate and produce substances such as oil sludge and carbon deposit. If there is a problem with the filter screen of the engine oil delivery system, such as the filter failure of the machine filter and filter collector, the engine oil mixed with impurities will be pulled out of the cylinder.
(4) Air filter failure
Let the air with impurities enter the engine and the impurities fall into the engine oil, which has a great impact on the vehicles that are easy to burn the engine oil and blow by. It can be seen that cylinder pulling accident, mechanical failure and lubrication system failure may be caused. The possibility of cylinder pulling caused by the quality problem of engine oil is very small, which has little to do with the quality of engine oil.
Many people understand that if the viscosity of engine oil is too low, that is, it is thin, it is easy to turn on the red light and poor lubrication. In order to avoid this bad phenomenon, some people will mistakenly think that the more viscous the engine oil is, the better, and even judge the quality of an engine oil only by viscosity. If the viscosity of engine oil is high, it is considered as good oil, regardless of the grade and brand, Therefore, the phenomenon of misidentification and misuse of engine oil is more common. In fact, for a designated excavator, the engine oil with its applicable grade and viscosity brand is not applicable to every excavator with high viscosity oil. For excavators that have been used for a long time, the parts are worn to a certain extent, and the clearance of friction parts is larger. Using high viscosity oil is conducive to strengthening its sealing performance, and the effect will be better.
