Common spark plug faults can be summarized into two types. One is that the spark plug has deposits, and the other is that the spark plug is heavily ablated.
1. There are deposits on the spark plug
Deposits sometimes stick between the top of the spark plug insulator and the electrode. Car owners should not underestimate this type of sediment.
In severe cases, this situation can lead to engine malfunction. After cleaning the spark plugs, the vehicle may operate normally for a while, but a similar situation will soon occur again. Indeed, the presence of deposits on the spark plug is only a superficial phenomenon, which can be a sign of problems with other mechanical components of the vehicle.
Symptom 1: Oily deposits on the spark plug
Diagnosis: When oily deposits appear on the spark pluge, this indicates that lubricating oil has entered the combustion chamber. If there are oily deposits on only a few spark plugs, this may be due to damage to the valve stem oil seal. But if the spark plugs in each cylinder block have this kind of deposit stuck on them, it means there is an oil leak in the cylinder. Generally speaking, when the air filter and ventilation device are clogged, the cylinder is prone to oil leakage.
Symptom 2: Black deposits on the spark plug
Diagnosis: There are black deposits on the spark plug electrode and inside, which usually indicates that the mixture in the cylinder is too rich. Car owners can increase the engine speed for a few minutes to burn off the layer of black soot left on the electrodes.
2. Removal of the spark plug
When the car owner notices scarsRices or damage on the top of the spark plug, or melting or removal of the electrode, this indicates that the spark plug has been damaged and needs to be replaced at this time. During the replacement process, car owners can check for symptoms of spark plug removal and color change.
Symptom 1: The electrode is melted and the insulation is white
Diagnosis: This phenomenon indicates that the temperature in the combustion chamber is too high. This may be due to excessive carbon deposits in the combustion chamber, making the valve clearance too small, further causing the exhaust valve to overheat or the cooling device to malfunction. When the spark plug is not tightened to the specified torque, the electrode will melt and the insulator will appear white.
Symptom 2: The electrodes are rounded and the insulation is scarred
Diagnosis : This indicates that the engine is in pre-ignition. The ignition timing may be too early or the engine may be igniting. The octane rating of the gasoline is too low or the spark plug is hot. The value is too high and for other reasons.
Symptom 3: The top of the insulation is broken
Diagnosis: Generally speaking, detonation combustion is the main cause of insulation failure. Premature ignition timing, low gasoline octane, and excessive combustion chamber temperature can cause engine knocking and burning.
Symptom 4: There are gray and black stripes on the top of the insulator
Diagnosis: The appearance of such stripes indicates that the spark plug has leaked and The car owner must replace it with a new one unconditionally.