How to Replace Car Spark Plugs?
2 Answers
Steps for replacing 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 any external debris like leaves or dust and ensure they are thoroughly cleaned. 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 firing order and secure the cover. If a spark plug is damaged, it can directly cause issues such as leakage in the vehicle's ignition system, increased fuel consumption, reduced power, and most notably, difficulty starting, affecting the vehicle's normal operation. Severe spark plug erosion—such as scarring, damage, or melted electrodes—indicates that the spark plug is ruined and should be replaced. Under normal maintenance conditions, spark plugs should be replaced every 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it's recommended to follow the owner's manual. For reference, the following standards can be used for maintenance replacement: platinum spark plugs at 40,000 km, standard nickel alloy spark plugs at 20,000 km, and iridium spark plugs at 60,000 to 80,000 km.
As an experienced auto mechanic, I'll walk you through replacing a faulty spark plug. First, make sure the engine is completely cool to avoid burns. Gather your tools: a spark plug socket wrench, new spark plugs, and possibly a torque wrench—regular wrenches can damage the threads. Step by step: Turn off the engine and disconnect the battery's negative terminal to prevent shocks. Gently pull off each spark plug wire without breaking it. Use the wrench to unscrew the old plug counterclockwise, then check if the gap is correct (typically 0.7 to 1.0 mm). Before installing the new plug, apply anti-seize compound, then screw it in clockwise by hand before tightening—don’t overtighten to avoid damaging the cylinder head. Reconnect the wires and battery. Test by starting the engine and listening for unusual noises. Common issues include incorrect gap or wrong plug type, which affect ignition and fuel efficiency. Replace plugs every 30,000 miles to prevent rough idling or poor acceleration.
