The presence of oily deposits on the spark plug indicates the entry of lubricating oil, while the cracks on the top of the insulator may be due to the low grade of gasoline. When maintaining a car, more attention should be paid to the condition of the spark plug, as a high-performance spark plug can enhance the vehicle's power performance. Generally, the service life of a spark plug is 15,000 kilometers, and even long-lasting spark plugs do not last longer than 30,000 kilometers. However, many car owners often encounter various problems with their spark plugs, which shorten their normal service life.
In fact, the operating temperature of a spark plug is quite high. During normal engine operation, the temperature of the insulator skirt of the spark plug generally remains between 500 and 600 degrees Celsius. Both excessively high or low temperatures have adverse effects on the spark plug. When the temperature of the spark plug is too low, carbon buildup tends to occur on the insulator of the spark plug, ultimately leading to electrical leakage and misfiring. If the operating temperature of the spark plug is too high, it can easily cause pre-ignition and engine knock. At the Chery Automobile Training Camp, the staff at the dealership summarized the common faults of spark plugs into two types. One is severe erosion of the spark plug, and the other is deposits on the spark plug.
Spark plug erosion
When the car owner discovers scars or damage on the top of the spark plug, or melting or ablation of the electrode, it indicates that the spark plug has been damaged and should be replaced. During the replacement process, the car owner can inspect the symptoms of ablation and changes in color of the spark plug.
Symptom 1: Electrode melting and insulator turning white
Diagnosis: This phenomenon indicates that the temperature inside the combustion chamber is too high. This may be caused by excessive carbon buildup in the combustion chamber, resulting in too small a valve clearance, which in turn leads to overheating of the exhaust valve or poor operation of the cooling system. When the spark plug is not tightened to the specified torque, it can also cause the electrode to melt and the insulator to appear white.
Symptom 2: The electrode becomes rounded and the insulator bears scars
Diagnosis: This indicates that the engine is experiencing pre-ignition, which may be caused by factors such as too early ignition timing, too low gasoline octane rating, or too high heat value of the spark plug.
Symptom 3: Fracture at the top of the insulator
Diagnosis: Generally speaking, knock combustion is the primary cause of insulator cracking. Factors such as premature ignition timing, low gasoline octane rating, and excessively high temperature within the combustion chamber can all lead to engine knock combustion.
Symptom 4: There are grayish-black stripes on the top of the insulator
Diagnosis: The appearance of such stripes indicates that the spark plug has leaked, and the owner needs to replace it with a new one unconditionally.
