How to Determine Faults by Spark Plug Color?
2 Answers
Spark plugs turning black is a fault signal; the blackening is due to an overly rich air-fuel mixture, requiring timely cleaning or direct replacement of the spark plugs. Steps for replacing spark plugs: Open the engine 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. When removing, check for any external debris like leaves or dust and ensure thorough cleaning. Place the new spark plug into the spark plug hole, hand-tighten it a few turns, then use the socket to tighten it further. Reinstall the high-voltage ignition wires according to the firing order and secure the cover. Spark plug replacement intervals: Under normal maintenance conditions, replace spark plugs every 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it's advisable to follow the user manual. The following standards can be referenced for maintenance replacement: Replace platinum spark plugs at 40,000 kilometers, standard nickel alloy spark plugs at 20,000 kilometers, and iridium spark plugs at 60,000 to 80,000 kilometers.
Last time when changing the spark plugs, the mechanic taught me that their color is like a health check-up report. Normal color should be grayish-brown or light brown, indicating proper combustion. If they appear black and sticky, it's likely due to an overly rich fuel mixture or oil burning - my car had this issue last time, which turned out to be caused by aging valve stem seals. If they turn pure white or even develop bubbles, it might indicate incorrect ignition timing or cooling system problems, which often happens during long summer drives. The most alarming is seeing brick-red coloration, which means you've used substandard gasoline with metal additives deposited on the electrodes. It's recommended to check them every 20,000 kilometers and address any discoloration early to prevent engine damage. Always refuel at reputable gas stations - this isn't an area where you should cut corners.
