Spark plugs are among essential components in our car. Poor quality spark plugs could result in poor engine performance and this cause higher fuel consumption. We should be aware that the car may not run smoothly and permanent engine damage could happen. We should know how well our car performs and whether new problems come up. In this case, we should know the condition of normal spark plug and it is important to know the condition of poorly performing plugs. A normal plug could have slightly worn off electrode greyish tan color. It should work well under normal heat range and correct operating condition.
There are conditions of problematic spark plugs that we should know. We should look for possible carbon deposits around the plug. If there are dry, sooty deposits; this could indicate weak ignition and rich mixture. With improper spark plugs, the engine may hesitate, misfire or start rather hardly. In this situation, we should also check for worn ignition points, high float level, sticky choke and clogged air cleaner. If our spark plugs tend to foul easily, due to specific engine characteristics or problems, then we should choose spark plugs with longer core nose.
Ash deposit is another condition that could indicate poor spark plugs and it is different with carbon deposits. If our spark plugs seem to have light brown deposits, then it is a good indication that they have problems. These deposits could be produced by oil or fuel additives. When enough ash deposit accumulates on the spark plug, there could be misfire and engine hesitation. If this problem continues to occur, we would need to replace the valve guide seal. Spark plugs with ash deposits will reduce the overall mileage. Without proper seal, oil will seep into the combustion chamber, causing a wide variety of problems.
Oil deposit is one more condition that we should consider and this is apparent by the oil coating. This could be due to poor oil control, especially when oil has seeped into the combustion chamber. This could be caused by worn valve guides. If there’s hesitation, misfire and hard starting, then it is important to check the valves. Spark plugs could also overheat during operation and this can be indicated by worn electrodes and blisters on insulators. Overheating can cause shorten plug life. In this condition, it is important to make sure that these plugs are appropriate for engine’s temperature range. Mechanics could fix this problem by leaning the fuel mixture, checking the intake manifold vacuum for leaks and over-advancing the ignition timing. In this case, we should be sure that the level of coolant is correct and the radiator is clean. Detonation is another serious problem that we should consider and this could be caused by damaged insulators. Preignition is among the worst conditions that could affect spark plugs. In this case, electrodes could melt with insulators that have turned white in color.