* Tools and Supplies:
* New spark plugs (NGK Iridium IX spark plugs are highly recommended)
* Spark plug wrench (16mm)
* Socket wrench (10mm)
* Gapping tool (if necessary)
* Dielectric grease
* Anti-seize lubricant
Step 1: Prepare the vehicle.
- Turn off the engine.
- Allow it to cool down for at least 30 minutes.
- Disconnect the negative terminal of the battery. (optional, but recommended)
- Remove the engine cover.
Step 2: Remove the ignition coils.
- Use a 10mm socket wrench to loosen the bolts holding the ignition coils in place.
- Remove the bolts and carefully lift the ignition coils out of the spark plug wells.
Step 3: Clean the spark plug wells.
- Use a vacuum cleaner or compressed air to remove debris from the spark plug wells.
Step 4: Check the spark plugs.
- Inspect the old spark plugs for wear, damage, or deposits.
- Replace any spark plug that shows signs of wear or damage.
Step 5: Gap the spark plugs (optional).
- Some spark plugs may require gapping to ensure the proper air gap.
- Use a spark plug gapping tool to check the air gap and adjust it if necessary.
Step 6: Apply anti-seize lubricant to the spark plugs.
- Apply a small amount of anti-seize lubricant to the threads of the new spark plugs.
- This will help prevent the spark plugs from seizing in the cylinder head.
Step 7: Install the new spark plugs.
- Screw the new spark plugs into the cylinder heads by hand until finger-tight.
- Use the spark plug wrench to tighten the spark plugs to 18-21 ft-lb (25-28 Nm).
- Be careful not to overtighten the spark plugs, as this can damage the cylinder heads.
Step 8: Reinstall the ignition coils.
- Carefully put the ignition coils back into the spark plug wells.
- Secure them in place with the bolts you removed earlier.
- Tighten the bolts to 10-11 ft-lb (13-15 Nm).
Step 9: Reconnect the battery.
(if you disconnected it earlier)
Step 10: Start the engine and check for misfires
- Start the engine.
- Listen for misfires or any unusual noises.
Step 11: Replace the engine cover.
Note: If you experience any misfires or other problems after replacing the spark plugs, you may need to have the vehicle's computer reset or reprogrammed.
Changing the spark plugs on a Subaru Outback is a relatively simple task that can be completed in approximately 30-45 minutes.
