What is a spark plug socket?
Spark plug sockets are used to fit or remove spark plugs from engines.
They will often have a foam rubber insert that sits inside the socket and serves to help hold the spark plug snugly, and prevent it from being damaged by the socket’s internal walls.
Spark plug sockets are longer than standard sockets and have a larger opening depth and clearance depth (see What socket sizes are available? for more information), to accommodate the top of the spark plug.
How are spark plug sockets used?
Spark plug sockets are used in exactly the same manner as standard sockets (see How to use a socket with a ratchet wrench). They attach to a turning tool with a square drive socket and also have a hex or bi-hex head, just like standard sockets.
When you are fitting a spark plug, you should use a torque wrench with your spark plug socket. This is to ensure that you do not over tighten the spark plug, which could damage it. You should be able to find the correct torque setting for your vehicle’s spark plugs in the user manual.
On some engines, the spark plugs will be recessed and you may have to use an extension bar with the spark plug socket in order to reach them.
For more information, see: How to use an extension bar with a ratchet and socket?
What spark plug socket sizes are available?
Spark plug sockets come in the following sizes: 16mm, 18mm, 21mm, ⅝” and 13/16″.
Make sure you always use the correct size spark plug socket for your car. Using the wrong size or an imperial size spark plug socket on a metric spark plug, or vice versa, is likely to damage the spark plug and could make it impossible to remove.