1. Preparation:
* Safety First: Disconnect the negative battery terminal. This prevents accidental shorts and shocks.
* Gather Tools: You'll need a spark plug socket (usually 5/8" or 13mm, deep well is recommended), a ratchet, extension(s) (likely multiple, varying lengths), a swivel socket adapter (highly recommended), possibly a universal joint, and a torque wrench. A magnetic pickup tool will be invaluable for retrieving dropped parts. Gloves are also a good idea.
* Consult a Repair Manual: A Haynes or Chilton manual specific to your year and model will provide detailed diagrams and torque specifications. This is highly recommended, especially for your first time.
* Clean the Area: Use compressed air to blow away any loose debris around the spark plug wells.
2. Accessing the Spark Plugs:
This is the most difficult part. The rear (firewall-side) plugs are notoriously hard to reach.
* Raise the Engine (Optional but Highly Recommended): Consider slightly raising the engine using a jack and jack stands. This provides significantly more room to maneuver your tools. Consult a repair manual for proper lifting points. If you do this, properly secure the engine to prevent it from falling.
* Remove the Upper Intake Manifold (Possibly Necessary): Depending on your comfort level and access, you may need to remove the upper intake manifold. This gives much better access, but it's a more involved process requiring additional tools and time. Consult your repair manual for steps.
* Use Extensions and a Swivel: The key to reaching these plugs is using various extensions to get the correct angle and leverage. The swivel socket adapter is crucial for navigating the tight space and awkward angles. Experiment with different combinations of extensions and the swivel.
3. Removing the Old Spark Plugs:
* Loosen the Plugs: Carefully insert the spark plug socket and loosen each plug by hand (or with a ratchet if your hand is not big enough) BEFORE removing any further. This is the best method to prevent cross-threading. Sometimes a little PB Blaster or similar penetrating lubricant applied earlier will help loosen them.
* Remove the Plugs: Once loosened, carefully remove each plug with the ratchet. Keep the ratchet handle fairly low to prevent interference with the surrounding engine components. Use a magnetic pickup tool to keep track of the spark plugs as you remove them.
4. Installing the New Spark Plugs:
* Gently Install: Hand-thread the new spark plugs into the cylinder head until they are snug. Do not force them!
* Tighten with Torque Wrench: Use your torque wrench to tighten the plugs to the manufacturer's specified torque (consult your repair manual). Over-tightening can damage the threads. Once you reach the correct torque, stop immediately.
5. Reassembly:
* Reconnect Everything: Carefully reattach any components you may have removed (like the upper intake manifold), paying close attention to connections and proper seating.
* Lower the Engine (if applicable): If you raised the engine, carefully lower it back to its original position.
* Reconnect the Battery: Reconnect the negative battery terminal.
Important Considerations:
* Gap: The spark plugs may need to be gapped correctly. Check the specifications in your repair manual.
* Photographs: Take pictures as you disassemble things to help you remember how everything goes back together.
* Patience: This is a challenging job, particularly for beginners. Take your time, and don't rush. If you get frustrated, step away for a bit.
If you're uncomfortable tackling this yourself, consider taking your Impala to a qualified mechanic. The risk of damaging threads or other components outweighs the cost of professional labor in many cases, especially if you don't have the proper tools or experience.
