Things to Know About Spark Plugs - information from the the pros at Shingle Springs Subaru

Of all the various parts that are essential for a vehicle's performance, there are maybe none more undervalued than the spark plug. These little parts are found in every gas-powered internal combustion motor and are what ignites the fuel/air mixture in order to turn the piston over and drive the car forward. Despite their importance, they are often neglected during maintenance due to a general lack of understanding regarding exactly what spark plugs are and what they do. To help correct this lack of understanding, here are 5 important things to know about spark plugs.

Spark Plug Image

5. What Are Spark Plugs?

Spark plugs are essentially little electrodes that send a spark that ignites the fuel/air mixture that gets pushed up the cylinder where the plug sits. One side of the plug has threads and actual electrode, and the other side is a terminal that the spark plug wire connects to. Spark plugs are usually screwed into the head of the engine and are connected to a series of wires that tell the plugs when to send the spark. If there is a problem with the spark plug or its wiring, then it won't ignite the fuel and the vehicle will misfire.

Spark plug in housing

4. Are There Different Kinds?

There are essentially three different kinds of spark plugs: copper, platinum, and iridium. These different types of plugs are the same in design and differ only in materials and conductivity/life span with copper having the highest conductivity and the shortest lifespan. Each engine was designed with a specific kind of plug in mind, so it's important to research exactly what your engine's manufacturer suggests.

3. How Long Do They Last?

The lifespan of a spark plug can range depending on its age, the amount it has been used, and the material it's composed of; however, generally speaking spark plugs have a very long lifespan compared to other auto parts. Every manufacturer has a suggested timeframe for replacing spark plugs. For example, Subaru suggests replacing their spark plugs every 60,000 miles.

Worn Spark Plug

2. Should Mine Be Replaced?

There are several indications that it's time for you to change your spark plugs. First and foremost, if you've reached the suggested mileage for your vehicle to change them. After that, if you notice your vehicle has not been running quite right, idling rough, or consistently misfiring, it may be time to change your spark plugs. Before you do, be sure to check their condition. It's possible that there's a different problem causing the malfunctions.

In order to inspect the spark plugs, first make sure your vehicle is turned off and the hood is popped. Then locate the spark plug wires- again, these are usually located on the engine head. Simply remove the wire from the terminal and unscrew the plug- you should use a special spark plug socket for this part. Once you've removed them, inspect the electrode side of the plug. If there is a large amount of discoloration, corrosion, or sediment buildup in the electrode gap, then that spark plug needs to be replaced.

1. Can I Replace Them?

Yes, you can replace your spark plugs by yourself, but it is a serious procedure and it should only be performed by someone with knowledge and experience. When replacing spark plugs, you'll need to remove the wires from each plug. The problem is that each wire is programmed to tell a specific plug when to fire corresponding to the position of the pistons, and if those wires aren't put back on their specific plug position, it could cause harm to the engine- and possibly you. It's also important to note that over-tightening a spark plug upon replacement can damage the cylinder head.

If you're going to change your Subaru's spark plugs, make sure to use OEM parts and use a gap-gauge to measure the gap in the new plug. Or, you can always bring it in to Shingle Springs Subaru and have our team of dedicated professionals do it for you.