Spark plugs come in various sizes, primarily referring to the hexagonal part (the hex) that a socket fits onto for installation or removal. This hex size determines the size of the spark plug socket you will need.
While spark plugs also have different thread diameters and lengths, the provided reference specifically discusses the socket size required, which directly corresponds to the plug's hex size.
Common Spark Plug Hex Sizes
The size of a spark plug hex can vary depending on the vehicle's make, model, and engine type. According to the reference provided, here are some of the common sizes you might encounter:
- Majority of Plugs: Require a 5/8” or 16mm socket. This is the most common size for many vehicles.
- Specific Applications:
- Some Ford vehicles use 9/16″ plugs.
- Some newer European and Asian vehicles use 14mm plugs.
- A few applications utilize 7/8″, 13/16″, ¾” or 18mm plugs.
Here's a quick look at the typical hex sizes:
| Hex Size (SAE) | Hex Size (Metric) | Common Application Notes |
|---|---|---|
| 5/8” | 16mm | Majority of plugs |
| 9/16” | - | Some Ford applications |
| - | 14mm | Some newer European and Asian vehicles |
| 7/8” | - | Less common applications |
| 13/16” | - | Less common applications |
| ¾” | 18mm | Less common applications |
Shape and Construction
Most spark plugs are 6-sided, or hexagonal, which allows a standard socket to grip them securely. However, there are exceptions; for example, some BMW engines use spark plugs that are not 6-sided.
Understanding the hex size is crucial because using the correct spark plug socket size prevents damage to the plug or the engine during installation or removal. Always check your vehicle's service manual for the specific spark plug size required.
