How to Determine if Spark Plugs Are Damaged?

[DelEsther]

Methods to determine if spark plugs are damaged: 1. Start the engine and let it idle, then touch the insulating ceramic part of the spark plug with your hand. If the temperature rises quickly and significantly, the spark plug is normal; otherwise, it is abnormal. 2. Remove the spark plug and observe its color. If it is reddish-brown or rust-colored, the spark plug is normal. 3. If the spark plug is oily, it indicates a misadjusted spark plug gap, excessive fuel supply, or a short or open circuit in the high-voltage wire. 4. If the spark plug is covered in soot, it suggests the wrong heat range was selected for the spark plug, the air-fuel mixture is too rich, or there is oil leakage. 5. If the spark plug has black deposits, it indicates carbon buildup. 6. If the spark plug shows severe erosion, with the top scarred, black cracks, or melted electrodes, it means the spark plug is damaged.

[BarrettRose]

When the vehicle has difficulty starting, I know it's time to check the spark plugs. Recently, my old car requires turning the key twice to start, and the engine idles roughly, consuming a lot more fuel when driving. Last week, upon inspection, I found that the electrodes of the middle cylinder's spark plug were completely worn out, and there was a crack in the ceramic body. Actually, you can also spot clues from the exhaust—black smoke from the tailpipe is particularly noticeable. I recommend checking them every 30,000 kilometers; if the electrode gap is too wide or the ceramic body is cracked, they need to be replaced. I usually replace the entire set to avoid imbalance in ignition, as replacing just one new spark plug might affect the overall performance when others are nearing the end of their lifespan.

[DiGriffin]

During a sudden acceleration, I once felt the car jerking forward as if being tugged. Experience told me it was likely a spark plug issue. Upon opening the hood, the ignition coils were scalding hot, and after unplugging them, obvious yellow leakage marks were visible on the ceramic bodies. Difficulty starting a cold engine is the most common symptom, along with backfiring from the exhaust. Now, I regularly use a borescope to inspect the combustion chamber—if the spark plugs are blackened with carbon deposits, they should be cleaned or replaced. Pay special attention to damaged ignition wires, as they can also affect the spark plugs. If the engine warning light flashes, it's crucial to investigate promptly.

[LeNova]

The most obvious sign of a bad spark plug is engine shaking. Last week while driving, I suddenly felt the steering wheel vibrating violently, and the engine warning light came on. Inspection revealed cylinder 2 wasn't firing, and the removed spark plug was completely soaked in gasoline. You might also notice heavier exhaust smell and poor acceleration under normal conditions. I always keep spare spark plugs in my car, especially checking before long trips. Remember - if the ceramic insulator shows cracks or the electrode is melted, it means they're done. Never try to make do with damaged ones.

[AubreeRose]

To determine the condition of spark plugs, I mainly focus on three aspects: whether cold starts are smooth, whether fuel consumption has increased significantly, and whether there's hesitation during acceleration. Last time I noticed my car lacked power when climbing hills, so I removed the spark plugs and found severe erosion on the center electrode with a gap nearly reaching 1.5mm. Here's a handy tip: reinsert the spark plug into the ignition coil and ground it against the engine casing to observe the spark - if it's weak or intermittent, the plug is faulty. Factory spark plugs typically need replacement at 40,000 km, but if you frequently take short trips, it's advisable to inspect them earlier.