Taking an Auto Mechanic Course? Explore This Guide to Changing Spark Plugs

Spark plugs play an essential role in the function and performance of a vehicle’s engine. In an internal combustion engine, fuel is turned into a source of energy by compressing a mixture of air and fuel within its cylinders, igniting the mixture to produce an explosion. This creates the power that propels a vehicle forward. In this process, spark plugs are responsible for the ignition of the air and fuel mixture itself. Without these components, there would be no explosion, and the engine would not be able to obtain the power needed to move a vehicle. 

Given the importance of spark plugs to an engine’s ignition system, it’s important to know when these components need to be changed, as well as how to change them. If you’re launching a career as a mechanic, explore an introductory guide to changing spark plugs below.

When Spark Plugs Need to be Changed: An Overview for Those in an Auto Mechanic Course

While spark plugs are made from resistant, long lasting materials, even these hardy components have an expiration date. After sustaining millions of explosions, they’ll eventually become worn out, at which point a weaker spark will be produced as the metal wears out and the gap between the two electrodes widens. 

When a weaker spark is produced, the engine’s performance is negatively impacted, creating problems such as low gas mileage, reduced acceleration capabilities, misfiring, or even an inability to start. In terms of expected lifespan, a vehicle’s owner manual will typically include an estimated spark plug lifespan. For “extended-life” spark plugs, which are more durable, the expected lifespan is around 160,000 km. Regular spark plugs may last for as little as around 50,000 km. After completing your auto mechanic training program, you can use this information to gauge when it’s time for a vehicle’s spark plugs to be replaced.

After many explosions, spark plugs can lose their ability to ignite the engine’s air/fuel mixture

Removing Spark Plugs from a Vehicle

Once you’ve determined that a vehicle’s spark plugs need replacing, you can begin by removing them. In order to avoid damaging the vehicle and ensure your safety throughout the removal process, make sure that the engine battery is disconnected and all dirt and debris is removed from the engine. Next, the spark plug wire can be removed. This rubber wire is responsible for delivering firepower from the ignition coils to the spark plugs, and will need to be removed before the spark plugs can be accessed. If the spark plugs have more than 160,000 km of use, it’s likely that this wire will need to be replaced too. 

Next, the coils which attach to the spark plug end can be removed, and should also be replaced with age. These coils contain a high voltage of charge, and must be handled with care to ensure that no voltage leaks and damages other engine components. Once the coils have been safely removed, the spark plugs can be unscrewed using a spark plug socket. 

Begin the spark plug removal process by taking out the spark plug wire

Installing New Spark Plugs

After completing your auto mechanic course, it will be important to verify that the spark plugs you’re installing as replacements are compatible with the vehicle in question. Check the manufacturer’s recommendations in order to ensure that you have the correct part numbers, and conduct a thorough inspection of the new spark plugs themselves in order to confirm that they aren’t damaged, bent, cracked, or chipped. Next, install the spark plugs, making sure to tighten them with the amount of torque specified in the owner’s manual. Once the spark plugs are in, you can reinstall the spark plug wires and the ignition coils, reattaching all electrical connectors and ensuring that the right wires are attached to the right spark plugs. After the battery is connected once again, you can start the engine to make sure that the replacement went smoothly. 

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