What Causes Spark Plug Failure?
3 Answers
Common causes of spark plug failure include the following: Incorrect spark plug gap adjustment. If the gap is too small, it not only limits the contact area between the spark and the air-fuel mixture but also suppresses flame kernel growth due to the flame-quenching effect of the electrodes. Although a spark occurs, it is weak, making it difficult to ignite the mixture. If the gap is too large, the ignition voltage provided by the ignition system may be insufficient to create a spark between the electrodes. Cracked spark plug skirt. High-voltage current leaks through the crack, preventing sparking at the electrodes. Electrode carbon buildup. Carbon deposits on the center electrode cause leakage to the surroundings instead of sparking to the side electrode. Excessive carbon buildup can short-circuit the spark plug, preventing it from sparking and eventually burning out the insulator, damaging the spark plug. Electrode damage. Prolonged electrical erosion from sparks or chemical corrosion from combustion gases can cause the electrodes to break or detach, preventing sparking. Low spark plug insulation resistance. This weakens the ignition voltage applied to the spark gap, resulting in weak sparks or a complete loss of ignition function. Short circuit in high-voltage wires. If the high-voltage ignition wire from the ignition coil to the distributor leaks, the entire engine may fail to start. If the wire from the distributor to the spark plug leaks, the spark plug in one cylinder may not spark. Burnt platinum contacts. This can cause all spark plugs to fail to spark, preventing the engine from starting or running normally. Symptoms of spark plug failure include: Difficulty starting the car, whether cold or hot, often requiring multiple attempts. Engine shaking, noticeable while driving. Reduced power, with a noticeable lack of acceleration compared to normal conditions. Increased fuel consumption. Engine stalling. Failed emissions tests. Faulty spark plugs should be replaced promptly. The replacement steps are as follows: Open the hood and remove the engine's plastic cover. Disconnect the high-voltage wires, marking each cylinder's position to avoid confusion. Use a spark plug socket to remove the spark plugs one by one. Check for debris like leaves or dust around the area and clean it thoroughly. Place the new spark plug into the spark plug hole and hand-tighten it a few turns before using the socket wrench. Reinstall the high-voltage wires in the correct firing order and reattach the cover. Spark plug replacement interval: Typically, spark plugs should be replaced every 40,000–60,000 km under normal maintenance conditions. However, this may vary depending on the brand and engine type, so refer to the owner's manual for specific recommendations.
I've been driving for over twenty years and have seen many spark plug failures. The most common cause is natural wear of the electrodes after prolonged use, causing the gap to widen and reducing ignition strength. Another issue is poor engine combustion leading to severe carbon buildup covering the electrode surface, preventing spark generation. There's also the problem of mismatched spark plug heat range with the engine, such as using a low-temperature type that's prone to electrode erosion at high temperatures. Improper installation torque can damage the threads if too tight or cause air leaks and oil ingress if too loose. Poor fuel quality, like using substandard gasoline, accelerates carbon buildup. Problems in the entire ignition system, such as aging coils, can also affect spark plug performance. I remember after my last spark plug replacement, the car started much faster and fuel consumption decreased. So, it's best to replace them every 20,000 kilometers during routine checks rather than waiting for a failure that could compromise driving safety.
As a car enthusiast, I often research spark plug issues. The main causes are: excessive electrode gap is common due to natural aging from prolonged driving; oil or carbon deposits contaminating electrodes, which easily accumulate with incomplete engine combustion; incorrect heat range for the engine, causing overheating erosion or cold carbon buildup; improper installation like incorrect torque damaging seals; and ignition coil failures damaging spark plugs. Choosing the right spark plug model and using high-quality fuel can extend their lifespan. I make it a habit to check my spark plugs every six months, cleaning carbon deposits with a small brush - it makes the car run much smoother. Never overlook these small details, as engine performance depends on them.
