The service life of a spark plug is usually 15000km, and the service life of a long-acting spark plug is 30,000km. When the engine is running, the temperature of the spark plug insulator should be maintained at 500-600 ° C. If the temperature is too low, the insulator is easy to accumulate carbon, which may cause leakage and cause fire shortage; if the temperature is too high, it may cause premature ignition and knock.
The common failure phenomena of spark plugs in use are as follows:
First, the spark plug was severely ablated. Scarring, damage to the tip of the spark plug, or melting or ablation of the electrode indicates that the spark plug has been damaged and should be replaced. When replacing, the symptoms of ablation and the change of color should be checked in order to analyze the cause of the failure. (1) The electrode is melted and the insulator is white. It indicates that the temperature in the combustion chamber is too high. This may be due to excessive carbon deposits in the combustion chamber, excessive valve clearance, or excessive cooling of the cooling device, or the spark plug may not be tightened to the specified torque. (2) The electrode is rounded and the insulator is scarred. It indicates that the engine is prematurely burning, which may be due to premature ignition time, low gasoline octane number, and high spark plug heat value. (3) The top of the insulator is chipped. Knocking combustion is the main cause of insulator rupture. Too early ignition time, low gasoline octane number, and too high temperature in the combustion chamber may cause engine knocking combustion. (4) There are gray-black stripes on the top of the insulator. This stripe indicates that the spark plug has leaked and should be replaced with a new one.
Second, the spark plug has deposits. There are sometimes deposits between the tip of the spark plug insulator and the electrode, which can cause the engine to stop working in severe cases, such as cleaning the spark plug can be temporarily remedied. To maintain good performance, the root cause of the failure must be identified. (1) Oily sediment. Oily deposits on the spark plugs indicate that the lubricant has entered the combustion chamber. If it is only an individual spark plug, the valve stem oil seal may be damaged. If this deposit is stuck to the spark plug of each cylinder, it indicates that the cylinder has oil leakage. Check the air filter and ventilation device for blockage. (2) Black sediment. There are black deposits inside the spark plug electrode and inside, indicating that the mixed gas is too rich, which can increase the engine running speed, and last for a few minutes, and a layer of black soot remaining on the electrode can be burned.