How to Replace Engine Spark Plugs?
2 Answers
Method for replacing engine spark plugs: 1. Prepare the necessary tools for disassembly, including 10mm, 14mm, and 16mm sockets, a long extension bar, a ratchet wrench, a magnetic pickup tool, and a rag; 2. After the engine has completely cooled down, unplug the ignition coil connector, then use a 10mm socket to remove the mounting bolts. Once the ignition coil is removed, you can see the spark plug in the cylinder; 3. Depending on the size of the spark plug nut, use either a 14mm or 16mm socket with a long extension bar to loosen it by turning counterclockwise. Once loosened, use the magnetic pickup tool to remove the spark plug; 4. After removing the spark plug, if you don't install a new one immediately, reinsert the ignition coil or plug the spark plug hole with a rag to prevent dirt from falling in; 5. Use the magnetic pickup tool to hold the new spark plug and insert it into the hole, then reassemble following the reverse steps mentioned above. The torque for tightening the spark plug should not be too high, approximately 20Nm is sufficient; 6. After replacing all spark plugs, start the engine to check if they are functioning properly.
As a seasoned mechanic with ten years of experience, I often help friends replace spark plugs. The whole process starts with tools—a spark plug socket is essential, while other items like a torque wrench and gloves are also important. First, turn off the engine and let it cool for at least half an hour to avoid burns or engine damage, and remember to disconnect the battery's negative terminal to prevent short circuits. Remove the engine cover to locate the spark plugs, usually arranged per cylinder, with each plug connected by a wire—pull gently to avoid breaking it. Use the socket to unscrew the old spark plug counterclockwise, then check the electrode for wear or carbon buildup; black spots indicate incomplete combustion. Before installing a new spark plug, adjust the gap using a gap gauge, typically between 0.8 to 1.1 mm depending on the vehicle model. Choosing the right type, such as iridium plugs, ensures greater durability and longer lifespan. Avoid overtightening during installation to prevent thread damage—I prefer using a torque wrench set to the manufacturer's specification (e.g., 15-20 Nm). After replacement, test-drive to check idle stability. Regular replacement every 40,000 km improves fuel efficiency and boosts performance. Dirty spark plugs can cause delayed ignition, leading to engine vibrations—early maintenance ensures safety first.
