Mazda 3 Spark Plug Change

The spark plug change is fast and fairly easy on the Mazda 3 as all the plugs are right on the top of the engine. This job can save you up to $200 over the dealership price.

Get all your tools prepared in advanced
Ensure you have a 14mm spark plug socket. This is very important
The Laser Iridium plugs are recommended, but they are a bit more expensive
The engine cover lifts up in the front and slides forward to remove it from the engine bay
Use compressed air to dust off the top of the engine so that nothing falls into the engine once the plugs are out
There is a bracket secured with 5 x 10mm nuts that needs to be removed
A socket can be used to remove the 10 mm nuts
Once all 5 nuts are off the bracket can be lifted straight off the engine
The ignition coils are secured with a 10 mm bolt that must be removed once the electrical connector to the ignition coil has been removed
With the bolt removed the ignition coil can pull straight out
Insert the 14mm socket on an extention into the spark plug well to remove the spark plug
Plugs may initially be difficult to get moving but should come out without too much difficulty
The spark plug socket has a rubber insert that should hold the spark plug in place. A small magnet can also be inserted into the well to pick up the spark plug
You don't change the gap on the irridium plugs, if they are off you should return them. It is advised that you check the gap before installing. I used a small amount of anti-sieze, but it isn't needed on the NGK iridium plugs
Once again the socket will hold the plug. Don't just toss the plug into the spark plug well
Hand tighten the plug until initially being very careful not to cross thread. I went to 10 foot pounds which is on the low side of the recommended spec because I used anti seize. Without anti-seize I would have gone to 12-14 foot pounds
I used a Q-Tip to apply di-electric grease to the inside of the ignition coil
I reinstalled the coil back onto the spark plug
I re-connected the electrical connector
I secured the ignition coil with the 10mm bolt
And finally I tightened the bolt up. I didn't have a torque spec for this. I then repeated the process for the other 3 spark plugs
With all spark plugs changed out I reinstalled the ignition coil retaining bracket
I then re-installed the bolts that hold the bracket in place
Last step is the secure the engine cover to the engine. Then start the car up and go for a test drive

Tools Used:

14 mm spark plug socket – https://amzn.to/2UB8P6d
NGK Laser Iridium plugs – ILKAR7L11 (94124) – https://amzn.to/3f4A0Q6
Spark plug gap gauge – https://amzn.to/3lCbZ5q
Dielectric grease – https://amzn.to/38Nk3g3
Anti-seize – https://amzn.to/2UvYTef
Torque Wrench – https://amzn.to/2UzoTWc

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