1. The piston pin is broken. The piston pin has insufficient strength or cracks; the gap between the piston pin and the piston and the connecting rod bushing is too large, resulting in greater impact; the center line of the piston pin hole is skewed and not perpendicular to the center line of the piston ; Missing installation of the piston pin snap ring or snap ring groove is worn, the piston pin leaps out, etc., will cause the piston pin to break.
2. The connecting rod splits or breaks due to the speed of the car, the connecting rod is overloaded or the connecting rod is bent or twisted, there are blisters, etc., which cause the connecting rod to split or break.
3. If the connecting rod bolt is broken, the torsion moment of the connecting rod bolt is too large, and the bolt is stretched and deformed; the torsion moment is too small, and the bearing gap becomes larger, resulting in impact load; the material of the connecting rod bolt is not good or the material of the connecting rod is reversed, slippery, and the carrying capacity is poor. Waiting to cause the connecting rod bolt to break.
4. When the valve falls into the cylinder, the valve stem breaks; the valve lock flap falls off, and the circlip loses its effect; the valve spring breaks and the valve falls into the cylinder.
5. Cylinder liner shoulder is broken. The rounded corner of the cylinder liner shoulder and the cylinder body is too small or there is no rounded corner. Under the action of the alternating load of the engine, the stress concentrates at this place and breaks; because the water blocking ring is not suitable, install When the cylinder liner needs to be beaten hard, the uneven force causes cracks in the weakened cylinder liner; due to various reasons, the cylinder liner tilts after installation, and the cylinder liner swings slightly in the longitudinal direction under the pressure of the piston side. The sleeve is broken.
6. Piston pin hole is broken. The gap between the piston and the cylinder liner is too small, and the piston is broken after sticking to the cylinder; the gap between the piston and the cylinder liner is too large, and the piston swings in the cylinder liner and is broken; the connecting rod is bent and twisted, causing the piston to suffer Large additional stress; excessive tightness of the piston and piston pin or improper assembly method, causing deformation or cracking of the piston; bad piston material, etc., causing the piston pin hole to break
7. Improper operation of stalling, starting or working, often banging the throttle, causing the speed to suddenly increase and decrease frequently, and the relevant parts are subjected to impact loads several times larger than that during normal operation, and fatigue damage causes the cylinder to be rammed.
8. Broken camshaft, runaway and forced start of the whole machine after a certain cylinder burns tiles, etc., it is also easy to cause cylinder ramming accidents.