So how do we change a spark plug? Let’s first look at what a spark plug is and what exactly the spark does to get a better understanding of just how vital this component is.

What is a spark plug for?

The spark plug is a vital part of your engine without it you wouldn’t be able to start the vehicle through ignition. The plug is a high voltage bridge that conducts an electric current, which creates a “spark” when electricity is passing through this bridge inside the engine and ignites the vapours beginning the process of combustion.

How long do spark plugs last?

The life of a spark plug really depends on several factors

  • The condition of your engine
  • The type of fuel
  • How well maintained the vehicle is
  • Even driving habits!
  • How the spark pluds were originally fitted
  • How long they have been in the vehicle

They are often relatively cheap and it is simple job so if you do need to change them often don’t worry you won’t break the bank. You will definitely save some money doing this maintenance yourself rather than taking the vehicle to a garage. In a large majority of vehicles this is a simple a quick job to do, for most people a simple mix up slows the process down you will see what I mean later.

Before you begin check your spark plug cables to see if you need to replace these or they could even be the reason you think you need to change you spark plugs. See our guide on checking your spark plug wires HERE

Replacing the spark plugs

Ok, let’s start. First gather as much knowledge you can about the vehicle make and model, not just for the type of spark plug but also to find out

Which tools you will need

  • How many spark plugs you need
  • The position and where the plugs are located
  • The recommended torque or “tightness” level of the spark plugs
  • Any procedures that may need to be carried out

You will need these tools

  • Ratchet Socket Wrench
  • 12 inch socket extension or recommended length
  • The correct or recommended spark plugs for your vehicle

Locating the Spark Plugs

The best suggestion of visually locating the Spark Plugs is to follow a thick rubber wire and you find them. With a four cylinder you will have four spark plugs and will normally be located towards the top of the engine and in a row. With a V8 normally you will have to locate the plugs on both sides of the engine, there will be four on the right and four on the left. Six cylinder engines can be either-or.

Removing the Spark Plugs

Once you have located the plugs get some making tape or anything else suitable for marking up these wires leading to the spark plugs. These wires are in a certain order and MUST be replaced back in the order they were originally positioned do not mix them up!
Begin at one end and pull the wire out off and up away from the plug with a firm hold, label it and repeat. Do not just vaguely take hold of the wire take hold at the nearest point you can toward the spark plug, damaging these wires can cause costs.

Once you have the plug wires removed and labelled in the correct order it is time to get you plug socket wrench and extension. Look inside the plugs housing and you will see exactly where you need to slot the extension down into. There may be some foam or rubber on the inside end this is to hold onto the spark plug while you remove it.

Set the wrench counter clockwise position it in to the gap and BEFORE turning the wrench make sure it is sat over the end of the plug as far down as it can go and remove the plug.

How Check A Spark Plug

With you old Spark plugs out take the chance to have a look. They will more than likely be dirty maybe a little black soot or if oily or white this could be the key indicator of other problems so take note of their appearance

Replacing the Spark Plug

Place the plug in the wrench socket and gently position down into the gap making sire the threaded ends lines up neatly with the female socket in the engine, push it all the down and carefully guide the plug into the hole. Try not to exert any force it should just sit into place, begin turning and screw the plug into position carefully by hand if possible to avoid cross threading.

When you can no longer turn by hand use the wrench again and tighten, if you do have a torque wrench use the recommended setting of torque level to avoid any over tightening or being too loose. Do not pull too hard.

Repeat these steps one plug at a time until you have replaced them all

  • Replace all of the wires back on to the plugs and any casing etc you have removed.
  • Make sure you put the wires back on correctly and on the right spark plug.
  • Make sure you do not have any tools or items left in the engine bay.

You can now start the engine and listen for any noises, if it runs rough stop the engine and check the plugs and connections again.

Take a break. You now know how to change your spark plugs, complete preventative maintenance and saved money in a few minutes!