When should you change the spark plugs in a petrol engine?

Your vehicle is comprised of myriad intricate mechanical components that require regular maintenance to ensure your car’s longevity. The savvy motorist can save time and money by performing a number of repairs at home – such as changing spark plugs.

change the spark plugs

Don’t wait for a problem to surface before changing your spark plugs – engine damage such as this can cost you dearly. Most vehicles require spark-plug maintenance every 30,000 miles or so to ensure the motor continues running smoothly. If you are new to do-it-yourself automotive maintenance, the task of changing your spark plugs may seem daunting at first, so here are some helpful guidelines to ensure everything goes without a hitch.

Always be prepared

Before getting started on changing your vehicle’s spark plugs, you will need some basic tools. The most important tool is your vehicle’s user manual, which will tell you exactly what type of replacement plugs you need, where the plugs are located, and how to remove them. You will also need a torque wrench, ratchet, and plug socket attachment (an extender can also be useful for some engines), as well as cleaning materials such as a compressed-air canister and clean cloth. A little penetrating oil will also come in handy should the plugs prove difficult to remove. It is also a good idea to pick up a spark- plug gap gauge to calculate the correct gap size.

Removing the old plugs

Be sure to allow your engine to cool for 3 to 4 hours before changing your vehicle’s spark plugs, both to protect the cylinder head threads from stripping, and yourself from potential burns. Atop the plugs are a series of plug wires. Grasp the wires by their boots or caps and gently twist them back and forth to remove them. It is very important that you label the wires so you can reattach them in the proper order. Once the wires are removed, thoroughly clean the plug recess to ensure no dirt or debris enters the cylinder head. Attach the plug socket to the head of the spark plug and apply firm pressure. Do not jerk the ratchet to remove stubborn plugs as this can damage the cylinder head threads. Instead, use a penetrating lubricant to loosen the threads, and then try again.

Installing your new hardware

Double-check the recommended spark-plug gap for your vehicle (the space between the metal electrodes at the plug’s tip), and use your gap gauge to ensure each new plug is configured to the correct gap. Screw each plug into the cylinder head and tighten it with the torque wrench as specified in your user manual. Then, reattach the plug wires in the proper order. If the wires appear worn or damaged in any way, now is a good time to replace those as well. Your vehicle’s user manual will provide detailed instructions on how to perform these repairs.

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