Spark Plug Failure: 3 Major Symptoms

Did you know that whatever happens to your spark plugs can serve as a huge clue to what ails your car? It's almost like an x-ray, a urine exam, or a blood test for cars in a sense!

With that said, whenever your spark plugs undergo lead fouling or the appearance of yellow-brown deposits on the plug's insulator nose, it probably means you're using a car that runs on leaded gas such as race cars.

Lead fouling is dangerous because it causes engine misfires hard accelerations or at high RPM. If the gasoline contains too much lead, lead fouling is likelier to occur. However, because in leaded gas cars, spark plugs are changed constantly, this problem has become less of an issue.

Spark Plug Destruction and What It Means

• Plug Breakage

Breakage happens when the insulator on the center electrode is bent or broken. This naturally results in power loss. There are many potential causes for this. It can be because of detonation caused by an extremely lean mixture of air and fuel. It can also be because of extreme temperatures/temperature changes leading to thermal expansion or thermal shock.

It can even be a broken insulator that's thermally triggered if cold fuel is sprayed on a hot insulator as well as drastically advanced timing. Electrode damage can also be because of excessive vibration or collision with internal engine components. Improper installation can lead to vibration and breakage. Meanwhile, collision is possible for spark plugs with too long of a reach.

• Melting Spark Plug

What could've happened if you find yourself with a melted spark plug? The melting could be partial or whole, with the ground or center electrode torched or melted like wax. This can naturally result in engine power loss. In any case, the melting of a spark plug is usually because of loose installation that keeps it from proper heat transference from its tip.

A spark plug melting within your engine is also indicative of hot spots or unusual heat spikes within your combustion chamber. Such intense temperatures might be caused by pre-ignition through an overly lean condition between your air and fuel mix. An improper heat range that's too low or improperly advanced timing can also cause melting shenanigans.

• Lead Erosion

What if your spark plug instead suffers from lead erosion, such that the spark plug surface may be thinning and the ground electrode's tip looks chipped? Obviously, the cause of the erosion is lead from leaded gasoline, which might compel you to use unleaded gasoline or a car that doesn't deal with lead fuel in the first place.

To be more specific, this spark plug condition is caused by lead compounds that, when under high temperatures, react to the electrodes chemically. Thusly, the plug's electrode material of nickel alloy becomes brittle and weak. This is caused by too much lead in your petroleum. Switch to unleaded unless you're driving a race car.