The oil deposit on the plug is lubricating oil, and the top of the insulator may be broken down by low gasoline label. When maintaining the car, more attention should be paid to the condition of the spark plug. The spark plug with good performance can improve the power performance of the vehicle. Usually, the service life of spark plug is 15,000 kilometers, and the service life of long-acting spark plug is not more than 30,000 kilometers. However, many owners of spark plugs often have such problems, which can not reach their normal service life.
In fact, the working temperature of spark plug is quite high. When the engine is in normal operation, the spark plug insulator skirt temperature is generally maintained between 500 and 600 degrees Celsius. Too high or too low temperature has a bad effect on spark plug. When the spark plug temperature is too low, the insulator on the spark plug is easy to deposit carbon, which eventually leads to leakage of electricity and lack of fire. If the working temperature of spark plug is too high, it is easy to cause premature combustion and engine knock. At Chery's car training camp, staff at the store categorized the common faults of spark plugs into two categories. One is that the spark plug is severely ablated, the other is that the spark plug has sediment.
Spark plug ablation
When the owner finds that the spark plug has scars or damages on the top, the electrodes melt and ablate, they all indicate that the spark plug has been destroyed. At this time, the spark plug should be replaced. During the replacement process, the owner can check the symptoms of spark plug ablation and the change of color.
Symptom 1: Electrode melting and insulator white
Diagnosis: This phenomenon indicates that the combustion chamber temperature is too high. This may be due to excessive carbon deposition in the combustion chamber, resulting in too small valve clearance, which further leads to overheating of the exhaust valve or poor work of the cooling device. When the spark plug is not tightened according to the prescribed moment, the electrode will melt and the insulator will appear white.
Symptom 2: Circled electrodes and scarred insulators
Diagnosis: This indicates that engine premature combustion may be caused by premature ignition time or low octane number of gasoline and high calorific value of spark plug.
Symptom 3: Top breakage of insulator
Diagnosis: Generally speaking, detonation combustion is the main cause of insulator rupture. Early ignition time, low octane number of gasoline and high temperature in combustion chamber may lead to engine detonation combustion.
Symptom 4: Grey-black stripes on top of insulator
Diagnosis: The appearance of this stripe indicates that the spark plug has leaked and the owner needs to replace the new parts unconditionally.