How to Replace Spark Plugs?
2 Answers
Steps to replace spark plugs: Open the hood, lift the plastic cover of the engine, remove the high-voltage ignition wires, and mark each cylinder's position to avoid confusion. Use a spark plug socket to remove the spark plugs one by one. While removing, check for external debris like leaves or dust and ensure they are cleaned thoroughly. Place the new spark plug into the spark plug hole, hand-tighten it a few turns, and then use the socket to tighten it further. Reinstall the high-voltage ignition wires in the correct firing order and secure the cover. How to determine if spark plugs need replacement: Remove the spark plug and inspect its appearance. A normal spark plug's insulator skirt and electrodes should appear grayish-white, grayish-yellow, or light brown. A properly functioning spark plug has a reddish-brown insulator skirt, with an electrode gap between 0.8-0.9mm and no signs of electrode damage. If the spark plug is covered in oil or deposits but not damaged, it can be cleaned and reused. If the spark plug is severely damaged—showing signs of blistering, black streaks, cracks, or melted electrodes—identify the cause of the damage, fix the issue, and replace the spark plug. Additionally, if the spark plug appears blackened as if smoked, it indicates an incorrect heat range selection, a rich fuel mixture, or oil leakage.
I've changed spark plugs myself many times, and it feels quite simple. Having the right tools ready is key—a dedicated spark plug wrench, torque wrench, and new spark plugs. Always ensure the engine is completely cooled before starting—safety first. Gently disconnect the ignition coil wires, avoiding any hard pulling to prevent damage. Use the wrench to unscrew the old spark plugs counterclockwise, and check for signs of wear or carbon buildup, which indicate it's time for a replacement. Install the new spark plugs directly—the gap is usually preset and doesn’t need adjustment, but applying some anti-seize lubricant to the threads is recommended to prevent seizing. Start by hand-tightening the plugs a few turns to align them properly, then gradually tighten with the wrench, being careful not to over-torque and damage them. After replacement, start the car—if the idle stabilizes smoothly, you’ve succeeded. Regular replacement every 30,000–50,000 km keeps the car running with better power and fuel efficiency.
