Spark Plugs Reveal Your Engine’s Condition

Spark Plugs Reveal Your Engine’s Condition

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With electronic devices managing the engine so well nowadays, motorists have less direct involvement with their engines. Where the motorist of the 1960s and earlier may have spent weekends taking spark plugs out to clean, engine management systems help to keep them cleaner so maintenance is less necessary.

However, for mechanics who are not dependent on those electronic diagnostic machines, a spark plug’s condition can tell a great deal about what’s happening inside the engine. Old hands can look at the spark plug’s colour and know if the mixture is too rich or lean, or if the ignition timing is way off.

If the combustion process is proper and tuning is right, a spark plug will have a grayish-white or grayish-yellow colour or perhaps be slightly brown at the insulator nose. There may be deposits but very minimal.

The presence of soot or oil mean that the mixture setting is off – perhaps too rich – or the air filter could be much too dirty. If there is a lot of oil especially, it could suggest that the piston rings are worn out and oil from underneath the pistons is getting into the combustion chambers. The usual solution to try is a hotter spark plug which can burn off the deposits. This type of spark plug heat range is usually recommended for those who do extensive town driving at very slow speeds.

There can also be extremely worn out spark plugs where the centre electrode is melted. This will result in misfiring and certainly loss of power. These indicate that the tuning is completely wrong or the ignition timing is far too advanced, or some other problems in the electrical system. The wrong heat range might also be used.

Thus the spark plugs can help with early detection of problems in the engine and save you money. Of course, there are also computerised machines to help provide diagnosis which can be accurate but it’s nice to know that when you are stranded in some remote place with a ‘cherry tree’ workshop, it may be possible to still figure out what is wrong with the engine by pulling out the spark plugs!

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