Cracked Spark Plug Discovered During Tune-up

cracked spark plug tune up

Cracked Spark Plug Found When Customer Complained Car Was Running Rough


Spark plugs are finger-sized pieces of ceramic and metal that provides the tiny electrical arc that ignites atomized fuel as it enters the combustion chamber. While they have gotten better and better over the years, they’re prone to occasional adjustment, cracking and replacement. While just about every other car repair takes a code reader and an educated mechanic to diagnose and fix, spark plugs remain accessible on most vehicles and easy to understand.

At the top of the spark plug sits the connector, or terminal. This is where the spark plug wire attaches. The terminal connects inside the plug to the copper core of the center electrode, which is surrounded by insulation. The bottom half of the plug is threaded. This is the part that gets screwed, gently yet firmly, into place. And the whole thing is capped off with a ground electrode. The ground electrode is made of metal, with options ranging from stainless steel to titanium. It can come in several shapes as well, from notched or Y-shaped electrodes to triple electrodes with three little arms that seem to reach for the tip of the center electrode.

The spark plug sits at the top of the cylinder head. The piston first travels down the cylinder, drawing in a mixture of fuel and air. The piston then goes back up toward the spark plug, compressing the mixture. At the very last second, when the piston is at its top dead center (TDC), the spark plug sparks and ignites the mixture. The piston is forced back down to create power for the vehicle, then pushed back up again to clear out the exhaust. At that point, the process starts all over again.

A Standard spark plug in modern engines has a copper center electrode core surrounded by a nickel alloy, which you can see at the tip of the plug. Inside the plug, the center electrode is encased in porcelain, which helps transfer heat from the engine to the cooling system. Premium spark plugs make use of precious metals, like platinum or iridium, in place of the nickel alloy. These metals have higher melting points and higher prices to match.

As regards temperature, spark plugs come in two basic varieties: cold and hot. Cold Spark plugs work best in high-compression engines. They have less insulation, so more heat can be transferred away from the combustion chamber to the outside of the engine. If the plug is not cold enough for a particular application, it cannot get enough heat out of the piston chamber. This can lead to pre-ignition, knocking, and permanent engine damage. Hot spark plugs have more insulation and are found in standard engines. The extra insulation keeps the plug’s temperature high enough to burn off carbon deposits, which allows for more time between spark plug changes. Spark plugs’ work status will directly reflect the efficiency of the engine. so, it should not be too cold or too hot.

Spark plugs usually need to be changed every 30,000 miles (48,280 kilometers). Some high-performance plugs can go as long as 100,000 miles (160,934 km) before replacement.

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