The abnormal noises in the engine cylinder can be summarized as piston knocking, piston pin knocking, piston top striking the cylinder head, piston top striking, piston ring striking, valve striking, and cylinder knock.
1.The impact sound of piston top and cylinder head
The abnormal sound of the piston crown hitting the cylinder head is a continuous metal tapping sound, especially at high speeds. The abnormal sound source is in the upper part of the cylinder, its sound is solid and powerful, and the cylinder head has vibration.
If you encounter such a situation during driving, the first aid is to remove the cylinder head and add a cylinder pad to raise the cylinder head without collision. However, when repair conditions are available, repairs should be carried out immediately to restore their good technical condition.
2.The abnormal sound of the piston ring
The abnormal sounds at the piston ring mainly include the metal knocking sound of the piston ring, the air leakage sound of the piston ring and the abnormal sound caused by excessive carbon deposit.
Cylinder knock refers to the "dangdang" or "click" of the piston at the moment when the piston starts working, or the piston swings in the cylinder when the piston moves upward, and its head and skirt collide with the cylinder wall Unusual sound. If it is a "dangdang" sound, it is mostly caused by poor lubrication of the cylinder wall. At this time, a little oil can be dripped into the cylinder, and then the engine is started. If the abnormal noise is reduced or disappeared, the abnormal noise is indeed caused by poor lubrication. If it is a "click" sound while the exhaust pipe emits blue smoke, it is generally due to the excessive gap between the piston and the cylinder wall.
4.The knocking sound of the piston pin
If the gap between the piston pin and the piston pin hole, the piston pin and the connecting rod small head bushing (or bearing) is too large, a sharp, crisp, high-pitched "click" metal percussion sound will be issued, similar to the use of a small hand The sound of the hammer striking the iron drill. The rule is that the engine does not sound when the cold car starts, and it sounds when the temperature increases, and the higher the temperature, the louder. If the ignition time is adjusted forward, the sound will speed up and increase. If the spark plug is cut off, the sound will weaken or disappear.