Gather your tools and materials. You will need:
- New spark plugs (check your owner's manual for the correct type)
- Spark plug wrench
- Socket wrench
- 5/8-inch spark plug socket
- Wire brush
Locate the spark plugs. The spark plugs are located in the cylinder head of the engine. On the Mazda 323, they are located on the front side of the engine, towards the top.
Remove the spark plug wires. Use your hands to remove the spark plug wires from the spark plugs. Be careful not to pull too hard on the wires, as they can be easily damaged.
Remove the old spark plugs. Use the spark plug wrench to loosen and remove the old spark plugs. Be careful not to drop the old spark plugs into the engine.
Clean the spark plug wells. Use the wire brush to clean the spark plug wells. This will help to ensure a good seal for the new spark plugs.
Install the new spark plugs. Hand-tighten the new spark plugs into the spark plug wells until they are snug.
Use the socket wrench to tighten the spark plugs. Tighten the spark plugs to 18 ft-lb (24 Nm).
Reattach the spark plug wires. Push the spark plug wires onto the new spark plugs until they are seated securely.
Start the engine and check for leaks. Start the engine and let it run for a few minutes. Look for any leaks around the spark plugs. If you see any leaks, turn off the engine and retighten the spark plugs.
