What is the tube above the spark plug?
3 Answers
The long component above the spark plug is called the ignition wire, also known as the spark plug wire, distributor wire, or high-voltage ignition wire. The spark plug mainly consists of a terminal nut, insulator, terminal stud, center electrode, side electrode, and shell. The main types of spark plugs include: standard spark plugs, extended insulator spark plugs, electrode-type spark plugs, seat-type spark plugs, surface-gap spark plugs, and surface-discharge spark plugs. Spark plugs are installed on the side or top of the engine. In early designs, spark plugs were connected to the distributor via ignition wires. Over the past decade, most car engines have switched to direct connection between the ignition coil and the spark plug. Spark plug working principle: The spark plug's ground electrode is connected to the metal shell, which is threaded into the engine block via the cylinder head. The insulator primarily isolates the metal shell from the center electrode. The terminal nut is the part of the spark plug that contacts the high-voltage coil. Current passes through the terminal nut and center electrode, then ionizes the medium between the center electrode and ground electrode to generate a spark, thereby igniting the air-fuel mixture in the cylinder.
I'm an auto mechanic. The tube on top of the spark plug is usually a high-voltage wire, responsible for transmitting high-voltage electricity from the ignition coil to ignite the gasoline in the engine. If this wire becomes aged, cracked, corroded, or has poor contact, the car may experience difficulty starting, shaking, increased fuel consumption, and in severe cases, complete breakdown. When repairing cars, I often advise car owners: first, turn off the engine, gently pull off the wire to check if the rubber layer has cracks; or use a multimeter to measure the resistance value—if it's too high, it needs replacement. Don’t overlook this small component during routine maintenance; its lifespan is generally 5-10 years, and it’s advisable to inspect it more frequently in urban driving conditions with more dirt. Delaying replacement may lead to additional damage to the spark plug, doubling the repair cost. Remember, regular maintenance can save you from major troubles—safety first. When buying parts, choose reputable brands and avoid cheap, low-quality products, as ignition system issues can be dangerous, especially on highways.
As an automotive engineer, let me explain the tube on the spark plug: This is actually the high-voltage wire of the ignition system. Its core function is to conduct tens of thousands of volts of high-voltage electricity, enabling the spark plug to ignite the air-fuel mixture smoothly. In terms of design, it features inner insulating material and a heat-resistant outer sheath to prevent electrical leakage or aging. The modern automotive trend is to reduce such wires, with some vehicles integrating the coil directly onto the spark plug for higher efficiency. If the tube fails and its resistance increases, it can lead to ignition delay, excessive emissions, or even trigger the engine warning light. From a technical perspective, I recommend: Choose silicone-material wires for better durability, and ensure the connectors are tightly secured during installation. The overall health of the system is crucial, as it affects the vehicle's power response and fuel consumption. Regularly check the resistance and physical condition to detect issues early and avoid a chain reaction.
