Old piston: the piston skirt if the deformation or serious wear and tear must be replaced with a new piston; piston with a washer if the gasket is loose to be replaced; cleaning piston top, piston ring groove and oil return hole, etc. deposition of carbon deposition, cleaning process should be The wear of the clearance on the side of the top groove must be carefully examined, the limit axial clearance between the new ring and the piston ring groove can not exceed 0.13mm.
Detection of cylinder and piston, connecting rod surface roughness and shape and position tolerance, should replace the defective components.
Please pay attention to the installation：
The piston rings must be loaded in sequence into the piston ring groove, starting with the bottom oil ring. With the piston ring pliers open the ring into the piston ring groove, but can not distend too much, otherwise it will cause ring fracture or permanent deformation.
The first ring is a barrel ring, the outer surface of hard chrome plating or spray molybdenum processing and fine work.
The second ring is usually a conical ring, with the marked side facing towards the top of the piston; the unmarked ring will have an inner or inner chamfer side facing up and the outer step facing down.
The third ring ring is generally spiral spring oil ring, install the first spiral spring spring into the piston ring groove, then the ring into the body, the spring support joint to be in the opposite position of the opening.
Assembly, the ring openings should be staggered in a "labyrinthine" structure, staggered angle of 90 degrees, respectively, 120 degrees, 180 degrees and do not put the opening on the piston pin; piston ring into the piston , Ring and ring groove should be applied to meet the requirements of the lubricating oil.
Crankcase ventilation should be good; the use of prescribed fuel, adjust the ignition time, to prevent the normal work of knocking; strictly control the engine, the engine should be properly controlled; Water temperature. At the beginning of the run-in, in particular, only the replacement of the piston ring and not replace the cylinder and piston, allowing a small amount of light blue smoke. Replacement of the new piston ring of the engine should be the appropriate specifications for cold run and low speed operation, is not allowed to run the engine running at high speed and high load to prevent the quality problems such as cylinder.
Piston is one of the most important parts of the engine, because it is always in the high temperature and pressure conditions, often prone to cylinder, fracture, damage or even pound and so on. In addition to the cause of the piston itself, other parts associated with any failure may lead to damage to the piston caused the engine failure. Here on the piston common faults to be analyzed.
First, the piston-related reasons tamper
The so-called pound cylinder is due to damage to a part of the engine and the impact of the engine body, resulting in engine cylinder liner and other important parts of the phenomenon of serious damage. Piston cylinder is one of the biggest fault of the engine, with great destructive force Piston strength is low, in addition to the chemical composition of the piston contains unqualified or unqualified microstructure, poor quality of the piston can not withstand high temperature and pressure high load working environment, Triggering crushing cylinder accident, the other there are the following reasons:
1, due to the valve into the cylinder causing the piston top surface damage, serious when the piston broken, resulting in crushing cylinder accident;
2, due to the piston pin fracture, the broken piston pin in the process of continuing the movement of the piston pin hole torque, piston pin broken, with the link after the continuous movement without further damage to the piston caused by crushing cylinder accident; Br /> 3, due to damage to the cylinder, the piston in the course of the movement due to resistance and broken, causing tamping cylinder;
4, due to lubrication system failure caused axle phenomenon, the piston is running beyond the normal load range caused by pound cylinder;
5, crankshaft fracture, connecting rod after the impact of piston and cylinder caused by pound cylinder;
6, the connecting rod can also lead to the loss of the piston screw damage caused by pound cylinder;
7, the engine after a serious pull cylinder piston and cylinder liner lock, the piston can not be reciprocated up and down under the circumstances by external force to break; Second, the reasons for piston cylinder Piston cylinder is a common failure, a slight case is due to dry friction to the piston surface of the hair; when you hear the engine with a slight knock on the cylinder sound, the piston surface has produced a metal melt, at this time if not timely maintenance will A piston and cylinder liner lock phenomenon. The reason is as follows:
1, lubricating oil is too thin to achieve effective lubrication or lubrication system (such as oil pump) failure causes the piston and the cylinder liner friction coefficient increases, resulting in cylinder;
2, improper adjustment of the engine ignition time, causing the engine knock, deflagration, the engine temperature is too high damage to the oil protective film, resulting in cylinder;
3, the engine air filter, lubricating oil filter, fuel filter is not timely replacement, cleaning, pollution of the cylinder working environment, resulting in cylinder;
4, the engine overload operation, cooling system problems caused by damage to the oil film cylinder;
5, the engine too much carbon, falling carbon into the cylinder block lead cylinder;
6, piston ring stuck, piston ring broken lead cylinder;
7, connecting rod bending to change the direction of the piston lead cylinder;
8, improper installation of the piston or piston and cylinder liner is not complete, the gap is too large or too small can also lead to cylinder.