Fault Diagnosis and Removal of Cylinder Wear
Cylinder wear failure phenomenon
①There is an obvious rattling sound during cold start, the temperature rises, and the sound weakens or disappears.
②The cylinder pressure is lowered.
③Sometimes the exhaust pipe emits blue smoke, and blue smoke emerges from the oil inlet.
④ The power of the engine decreases.
⑤ Fuel consumption increases.
Wearing Law of Cylinder and Its Reason
(1) Cylinder wear law
Viewed from the longitudinal section of the cylinder (in the direction of the cylinder axis): an irregular "cone" or "cone" with a large top and a small bottom. The most worn part: when the piston is at the top dead center, the cylinder wall corresponding to the first piston ring, and the upper port that the piston ring cannot contact has no wear, forming a "cylinder step". In special cases, the most worn part of the cylinder is in the middle (waist drum). On the same engine, the wear conditions of different cylinders are different. Generally, the front wall of the first cylinder and the rear wall of the last cylinder of a water-cooled engine wear more seriously.
From the cross section of the cylinder: uneven wear, wear into an irregular oval. The largest wear part of each cylinder in the circumferential direction: generally, the cylinder wall near the opposite side of the intake valve wears the most.
(2) Causes of cylinder wear
Under normal circumstances, the wear of the cylinder along the working surface in the movement area of the piston ring is an irregular cone shape up and down in the height direction. The most worn part is the cylinder wall corresponding to the first piston ring when the piston is at the top dead center position. On the other hand, the upper port where the piston ring does not contact the cylinder wall hardly wears and forms an obvious cylinder shoulder.
Reasons for big and small:
①Mechanical wear:
When the piston is at the top dead center, the burst pressure of the high-temperature gas is the largest, which causes the positive pressure of the piston ring to the cylinder wall to increase, the friction force also increases, the lubricating oil film is destroyed, and the cylinder wall corresponding to the first piston ring wears the most seriously.
②Corrosion wear:
Organic acids and acidic oxides (dissolved in water to generate mineral acids) generated by the combustion of the gas mixture. It has a corrosive effect on the surface of the cylinder, causing corrosion wear. The upper part of the cylinder block cannot be completely covered by the lubricating oil film, and the corrosion effect is more serious.
③Abrasive wear:
The dust in the air, the mechanical impurities in the lubricating oil, the wear debris in the engine, etc. enter the cylinder walls to cause abrasive wear. The dust in the air is sucked into the upper part of the cylinder, and its edges and corners are sharp, so the upper part of the cylinder wears the most. The reason for the shape of the waist drum: In areas with severe sandstorms, after a large amount of dust enters the cylinder, since the piston moves at the highest speed in the middle of the cylinder, the abrasive wear is the most serious.
Cylinder Wear Fault Diagnosis Method
①Detect the pressure of the faulty cylinder.
②Detect the cylinder diameter and cylindricity.
Cylinder Wear Technical Standard
The main indicators to measure the cylinder wear inspection are roundness and cylindricity. After the cylinder wears, the cylindricity error reaches 0.175-0.250mm. The circularity error reaches 0.050~0.063mm (whichever is the most worn-out cylinder), the cylinder The difference between the wear size and the standard size (the difference between the wear size of the Santana automobile cylinder and the standard size is greater than 0.08mm, and the difference between the wear size of the Toyota 8A automobile cylinder and the standard size is greater than 0.20mm), as one of the main basis for the overhaul of the automobile engine .
