The bad piston ring may be related to the air leakage caused by its wear or coke connection with the piston ring groove. If after cutting off a cylinder, the exhaust gas no longer from the oil or vent vent, the cylinder piston is not good use.
The cause of piston ring leakage
1. Piston ring groove wear. Piston groove wear is mainly in the ring groove under the wetting surface, resulting in wear of the original fondle is the impact of the gas ring and piston ring in the ring groove of radial sliding, so that the sealing effect of the second sealing surface decreased.
2. Piston ring wear. Because the material of piston ring is not matched with the cylinder wall (the hardness difference between the two is too great), the sealing of the ring becomes worse after the ring is worn
3. The piston ring opening gap is too large or when his mixing is not required, the sealing effect of the face ring becomes bad, throttling effect is reduced, the air leakage channel to increase the opening gap two diesel engines than the gasoline engine, and the first ring is larger than the second, third ring.
4. Improper distribution of piston ring openings. In order to reduce air leakage, strengthen the throttling effect of the ring opening, make the sealing gas route of the ring long, so the opening of the air ring according to the requirements of the operation.
5. When the engine works, when the balance bucket of various forces acting on the ring is in a floating state, it can cause the radial vibration of the ring, make the seal fail, and also may appear the circular rotation of the ring, which will make the opening stagger degree changes during installation, and also cause air leakage.
6. Piston ring fracture, adhesive, stuck in the ring groove, or piston ring installed in reverse, all make the first sealing surface of the ring lose the sealing effect and leak. For example, twisted and broken tapered rings are not installed in the groove of the ring as required.
7. Air leakage due to cylinder wall wear or marks or grooves affecting the seal of the first sealing surface of the air ring.
Piston ring leak check
1. Force in each cylinder (remove spark plug or fuel injector). A small amount of lubrication for the cylinder compression pressure inspection, if the oil is added, the cylinder compression pressure, it is proved that the piston ring seal is not strict.
2. The hardness of the air ring is larger than that of the cylinder. Using a soft piston ring will shorten the ring life. The ring and the cylinder of the hard and soft inspection, can be keng JJ or scraping force test scraping the lower edge of the cylinder and the ring for comparison.
3. Correctly grasp the timing of ring change. Ring change should be done when the cylinder wear is not heavy, the elasticity of the ring is not obvious, and the engine fuel and lubricating oil are not abnormal. If the cylinder wear in the allowable range, and the cylinder clearance is too large, the sound replacement of the piston, or just change the piston ring, "the original piston in the cylinder swing frequently, unable to control the ton plug ring and failure again.
4. The "cylinder shoulder" shall be scraped off with a scraper when changing the ring, and the carbon accumulation in the ring groove shall be removed. The opening of the ring shall be subject to the inspection of the lower part of the cylinder. In case of being broken by "cylinder shoulder", the ring is carbon stuck in the ring groove and due to insufficient ring opening gap and burst.
5. Before the piston ring is installed, the whole ring belt and part of the pin hole of the piston shall be immersed in clean thin lubricating oil to lubricate in advance to prevent the new piston pin from biting dead after the engine starts and the dry friction between the piston ring and the ring groove.
6. Improve engine maintenance quality, make the opening end gap, side gap and back gap of the ring meet the technical requirements, stagger the openings reasonably, strengthen the test of the leakage degree of the ring, and avoid the ring installation anti-o ring end gap as a straight cut, the ring should be flat during the clack repair.