Piston Ring is a metal ring inserted into the piston groove. There are two kinds of piston rings, compression rings and oil rings.
The compression ring can be used to seal the combustible mixture gas in the combustion chamber. The oil ring is used to scrape excess oil from the cylinder.
✔The method of judging the abnormal sound of piston ring
01）The metallic tap of the plug ring
▶When the piston ring is broken, or the gap between the piston ring and the piston ring groove is too large, it will cause a certain knocking sound.
▶The upper part of the cylinder wear, the piston ring and the cylinder can not contact the place almost no wear to form the step, such as improper repair of the piston ring and the cylinder step will issue a pure dumb "poof, poof" metal percussion sound, with the increase of the speed, the sound also increases.
02）There is a sound of leakage in the piston ring
▶Causes and characteristics: the piston ring elasticity is weakened so that the piston ring and the cylinder wall are not tightly sealed, the opening clearance of the piston ring is too large or the opening overlap, and the cylinder wall is scratch with grooves, which will cause the piston ring to leak.
▶Method of fault check: Inject a little lubricating oil into the cylinder, if the sound reduces or disappears, but soon appears, that is, the piston ring leakage.
03）Abnormal noise caused by excessive carbon accumulation in piston rings
▶Characteristics of sound: carbon accumulation too much sound, is a sharp "treble, treble". Sound, the engine sometimes not easy to stop.
▶The cause of carbon accumulation: the main reason is that the piston ring and the cylinder wall seal is not strict, the opening clearance is large, the piston ring is installed backwards, the opening is overlapped, the lubricating oil is caused by the combustion chamber, or because the gasoline label does not meet the requirements, the mixture is too strong, the air cleaner is too dirty.
▶Single cylinder fire break test, the sound decreases, but does not disappear, put the screwdriver on the spark plug or nozzle to listen, such as a "snap, snap" sound can be determined as the piston ring broken.
▶Careful observation, such as a "poof, poof" sound, and no change after fire break, can be determined as the piston ring collision cylinder shoulder.
▶When the engine cold car starts, it makes a "boom, boom" sound. Blue smoke can be seen at the oil filling port, and its frequency is consistent with the sound frequency. When the fire break test is performed, the sound disappears, and the smoke at the oil filling port decreases or disappears.
▶The engine temperature rises, if there is still an obvious gas channeling sound, and then the fire break test, but there is still an obvious gas leakage phenomenon at the oil filling port, it can be determined that the piston ring and cylinder wall seal is poor.
✔Cause analysis of abnormal ring sound of piston ring
▶The piston ring is broken.
▶Piston ring and groove wear, resulting in excessive back and end clearance, piston and cylinder wall sealing reduced.
▶After the cylinder wall is worn, the top shoulder appears. After readjusting the connecting rod bearing, the piston ring and the cylinder wall shoulder collide.
▶The clearance of piston ring ports is too large or the ports of each ring coincide with the opposite port.
▶The elasticity of the piston ring is too weak or the cylinder wall has grooves.
▶The piston ring sticks to the piston ring groove.
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