How to Check Spark Plugs for Detonation Damage

You should know how to inspect spark plugs and identify the symptoms that tell you when it's time to repair or replace your car parts. Even if you're already adept at checking your spark plug condition, you might miss something and fail to diagnose what's wrong.

You should do the following during inspection in order to prevent misdiagnosis or think that everything's fine when it's not. One sure sign of a faulty spark plug is if it has a crack or multiple cracks all over the surface of its porcelain cover.

There are also times wherein you'll come across a red coating on the ceramic insulation. Usually, it's from the low-quality unleaded fuel in the form of additive buildup, but still be on the lookout for it.

Spark Plugs and Detonation Damage

  • Detonation Damage on The Plug: Detonation, knocking, or pinging damage on your spark plug can be attributed to off-balance timing from your engine. Apart from knocks, the same consequence can be caused by poor-octane-rating gasoline. To prevent this, you might want to switch to higher-octane fuel and have your vehicle's spark plugs checked out by a pro mechanic just to be sure. He might identify other reasons for the pinging such as fuel injector failure, ignition delay, or a change in engine temperature. Check your OBD error message console for more details on what could be wrong with your engine.
  • Spark Plug Diagnosis: When inspecting your spark plug, take it off from where it's housed but keep it plugged into the cable. Afterwards, ground it unto the frame before starting your motor. It should produce blue sparks if it's working properly. However, if it doesn't produce sparks or if it produces yellow sparks then that's an indication of you needing to replace these plugs. There are issues with this testing method though. The spark plugs don't undergo the same pressure inside the chamber compared to the outside, so you have no guarantee they'll work even if they produce blue sparks. It provides a quick rule of thumb on the health of your plugs though.
  • The Consequences of Detonation: Allowing knocking to persist over many engine cycles or under extreme conditions can result in the destruction or significant damage of your engine. You may face particle wear from moderate detonation alone. This wear-down can then further worsen and travel through other car parts to the point of affecting your engine's oil system and getting trapped in the oil filter. This wear-down gives the appearance of your engine getting sandblasted or filled with abrasions or erosions. It can also come in the form of cavities all over your hydraulics. Meanwhile, detonation that's severe can lead to catastrophic events like a ruptured combustion chamber or melted holes on the cylinder head or piston.

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