On a 4-cylinder engine, spark plugs will be located on the top or side of the engine in a row. On an inline 6-cylinder, they are located on the top or side of the engine head. On V6 and V8-cylinder engines, plugs should be separated evenly on each side of the engine. Some cars have engine covers you’ll have to remove to see the spark plug wires, tracing them back to find the plugs themselves. You should always check your owner’s manual and look up where your spark plugs are, how many you have, the correct “gap” and the size socket needed to remove them. You should also number the corresponding leads to the cylinder so as not to confuse which lead goes where when replacing with new plugs. At this point, it is good practice to inspect the leads for any damage or cracks as replacement leads may also be required.
A ratchet socket drive wrench An extension bar Spark plug socket, usually included in most ratchet socket sets A spark gap gauge or feeler gauge, available at any auto parts store
When checking to see if the plugs need replacing, simply remove one spark plug and check the gap. If contacts are burnt out, refit the plug and lead to the correct torque setting then go to the auto parts store and get new plugs before removing any more. You will need to remove the plugs one at a time, keeping track of the order. Spark plugs fire in a specific order, and crossing a wire to the wrong plug will make the engine run rough or not at all and can cause damage to your engine. Remember: If you take out more than one spark plug at a time, keep track of your leads and the corresponding plugs by marking them with small pieces of masking tape. Label each wire numerically, then give the corresponding plug the same number.
If the distance of the spark plug gap is higher than it should be, but the plug is still of a relatively high quality and is an adjustable-gap plug, you can either try to change the gap by gently tapping the plug on a wooden surface with the gauge in between the plug gap until the desired measure is set at the correct measurement, or you can simply buy new plugs. It’s usually recommended that you replace the plugs after every 20,000 Km or 12,000 miles or as indicated in your vehicle owners manual. Spark plugs are not overly expensive, and it’s a good idea to replace them at regular intervals for trouble free motoring and a proper spark. [5] X Research source If you’re going to start changing your own plugs, invest in proper tools and equipment, such as a fine gap checker. It’s basically a metal ring you can use to see if the electrodes are close enough to fire properly. Feeler gauges are even more precise and give a wider range of applications. The same goes for parts: aways buy quality and or genuine parts, it is worth a few dollars more for peace of mind and reliability.
If the plugs are bent, black, or broken, you may have a mechanical problem with your engine and should consult a qualified mechanic or your local car dealer repair shop without undue delay. [7] X Expert Source Hovig ManouchekianAuto Repair & Design Specialist Expert Interview. 23 February 2021.
A good rule of the thumb is to get the same plugs you have in the car currently. Never downgrade to a less expensive plug and don’t think too hard about fixing something that works already. The manufacturer installed those plugs for a very good reason, so simplify the process and get the same ones when possible, provided they were the correct ones fitted! Check your manual or with your local dealer. [9] X Expert Source Hovig ManouchekianAuto Repair & Design Specialist Expert Interview. 23 February 2021. You can typically buy fixed gap or adjustable gap spark plugs, so it’s up to you if you want to check your plugs regularly and make minute adjustments. If you do, get adjustable plugs. Above all, you need to make sure the gap measurement is the correct measurement for your car. If you check it yourself, you’ll know for sure. Remove it from the package and do a quick check to verify the measurement.
