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How to Change Spark Plugs

91preludesi | Mar 10, 2011 |

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To install new spark plugs you will first need to gain access to all of the spark plugs. If you have a four cylinder this should be a fairly easy process. They are located either on top of the valve cover or directly in the side of the cylinder head. If you have a V6 or V8 some or all of them may be more difficult to access. Also with a lot of newer vehicles the manufacturers have decided to hide the engine under plastic covers. On certain models these covers will have to be removed to access the spark plugs.

Depending on the age and type of vehicle you have it may or may not have spark plug wires. Vehicles that have what is called a D.I.S., or Distributor-less Ignition System may not have spark plug wires, although some still have short wires. Instead of spark plug wires they have a separate coil for each spark plug. This is known as a Coil On Plug system.

After you have determined which type of ignition system you have you will need to either remove the spark plug wire, or coil pack. If you have spark plug wires, I strongly suggest that you replace the wires one at a time. If you remove all of the spark plug wires at once, you may put them back in the wrong order, causing the vehicle to run poorly, if it will run at all. You can also use a metallic (silver) Sharpie to write the cylinder number on the spark plug wires so you will know where they go. With the wires, or coil pack removed, use a spark plug socket with an extension and a ratchet to remove the spark plug. If the spark plug does not come out easily, do not force it. Instead, loosen it a little, and then tighten it back a little. Doing this several times while loosening it a little more each time will make the removal process easier.

To install the new spark plug, first insert it into the socket. You do not want to simply drop it into the hole. This could damage the spark plug or change the gap, which will result in poor vehicle performance. Using the socket and extension, lower the spark plug into the hole and begin to thread it by hand. Do not start the it with tools. If you damage the threads that are in the cylinder head it could end up being a costly repair. Once the spark plug is hand tight, use a ratchet to snug it down. It needs to be tight, but not over-tight. If the spark plugs on your vehicle are in a hard to reach location you can use a swivel spark plug socket. I also recommend using a locking extension when installing spark plugs. Spark plug sockets have a rubber insert inside them so that they can hold the spark plug without it falling out. This is great until you try to remove the socket. If you use a regular extension and try to pull it out you may leave the socket behind. Then you will spend the next 10 minutes trying to get the socket out. The spark plug socket will stay connected to the extension until you pull the quick release. This can save you a lot of time and headache. Finish replacing all of the spark plugs. When you are done replace any spark plug wires, covers, etc. that you may have had to remove.