How Long Does It Take to Replace 4 Spark Plugs?
4 Answers
Replacing one spark plug generally takes about half an hour, while replacing four takes approximately 2 hours. Function of Spark Plugs: Commonly known as spark plugs or "fire nozzles," their role is to discharge the high-voltage pulses delivered by the high-voltage wires (spark plug wires), breaking down the air between the two electrodes to generate an electric spark, which ignites the air-fuel mixture in the cylinder. Main Types of Spark Plugs: There are mainly standard spark plugs, insulator-protruding spark plugs, electrode-type spark plugs, seat-type spark plugs, pole-type spark plugs, surface-gap spark plugs, etc. Spark plugs, in coordination with the ignition system and fuel supply system, enable the engine to perform work, collectively determining the engine's performance to a large extent.
Replacing 4 spark plugs is actually quite quick. I just helped a friend with it last month. For regular family cars, a skilled mechanic can usually finish in about 40 minutes. Tasks like removing ignition coils and unscrewing old spark plugs require careful attention, and difficult-to-access positions might add an extra 10 minutes. The key is applying the correct torque during installation, as requirements vary by car model—German cars generally demand higher torque than Japanese models, for example. Last time, when replacing NGK spark plugs on a 100,000-km Golf, I also checked the cylinder compression and found slight carbon buildup in the third cylinder. After inspecting with a borescope, I recommended a follow-up cleaning. The whole process, including carbon cleaning, took 60 minutes. I recommend using spark plugs with the factory-specified heat range to avoid triggering the check engine light.
Over the years of repairing cars, I've replaced tens of thousands of spark plugs. Changing four in a four-cylinder car is basic skill. A skilled worker can finish in half an hour, while an apprentice takes about 45 minutes. The key is having the right tools - the spark plug socket must be the magnetic type. I once encountered a special case: when replacing spark plugs on a classic Focus last time, the ignition coil rubber had aged and got stuck, taking 20 minutes to remove it without damage. Actually, it's important to check the ignition coil condition during disassembly. Some shops charge extra labor fees precisely for this reason. I recommend choosing iridium spark plugs for better durability, as ordinary nickel alloy ones need replacement every 30,000-40,000 kilometers.
Last week, it was quite interesting watching my cousin change spark plugs at his shop. First, he removed the engine cover and blew off the dust with compressed air. When removing the ignition coils, they need to be pulled straight up—pulling at an angle can easily break the clips. It took 35 minutes to replace all four spark plugs on my Civic, mainly because each cylinder had to be handled individually. My cousin said naturally aspirated engines are simpler, while turbocharged cars require more disassembly and take about an hour. He chose NGK ILZKAR7B spark plugs, a resistor-type model that matches the ECU data. Remember to set the torque wrench to 25N·m—overtightening can cause thread stripping. The electrode gap on the old spark plugs had widened to 1.5mm, no wonder it was consuming more fuel. Next time, I plan to replace the ignition coils along with the spark plugs.
