Tools You'll Need:
* Socket Set: Specifically a deep well socket that fits your spark plugs (likely 5/8" or 13/16", double-check your owner's manual). A spark plug socket with a rubber insert is highly recommended to prevent rounding off the spark plug.
* Wrench: To loosen the coil packs. A 7/16" or 1/2" wrench might be necessary, depending on your vehicle. Again, check your owner's manual.
* Spark Plug Gap Tool: To check and adjust the gap (if needed) on your new spark plugs. Your owner's manual will specify the correct gap.
* Ratchet: To turn the socket.
* Extension: You'll almost certainly need an extension to reach the rear plugs. A flexible extension is very helpful.
* Needle-nose pliers or small pick: To help remove the coil packs if they are stubborn.
* Gloves: To protect your hands.
* Shop Rags: To clean up.
* New Spark Plugs: Make sure to purchase the correct type and heat range for your engine. Your owner's manual or a parts store can help with this.
* Dielectric Grease (Optional): To help prevent corrosion on the spark plug boots.
Procedure:
1. Safety First: Disconnect the negative terminal from your battery. This prevents accidental shorts and electrical shocks.
2. Locate the Rear Spark Plugs: The rear spark plugs are located at the back of the engine, often making access difficult. You'll likely need to work around the intake manifold and other components.
3. Remove the Coil Packs: Each spark plug is covered by a coil pack. You'll need to carefully unbolt the coil pack(s) from the engine using the appropriate wrench. Sometimes, these are stubborn and might require some gentle persuasion. Be careful not to damage the coil pack or the electrical connectors. Once unbolted, carefully disconnect the electrical connector.
4. Access the Spark Plugs: Now you have access to the spark plugs. With the right tools (socket, extension, ratchet), carefully remove the old spark plugs. Go slowly and avoid applying excessive force to prevent damaging the spark plug threads or the engine block. If the spark plug is particularly stubborn, apply penetrating oil and wait a few minutes before trying again.
5. Inspect the Old Spark Plugs: Check the condition of the old plugs. This can give you clues about potential engine issues.
6. Install the New Spark Plugs: Before installing the new spark plugs, check the gap with your spark plug gap tool and adjust if necessary. Carefully screw in the new spark plugs by hand until they are snug. Then, use the socket and ratchet to tighten them to the manufacturer's specified torque (look this up in your owner's manual – don't overtighten!).
7. Reinstall the Coil Packs: Carefully reconnect the electrical connector to each coil pack and rebolt them to the engine.
8. Reconnect the Battery: Reconnect the negative battery terminal.
9. Start the Engine: Start the engine and listen for any unusual noises. Check for any leaks around the spark plug wells.
Important Considerations:
* Access: This job is significantly more difficult than replacing front spark plugs due to limited access. You may need to use a mirror or a flashlight to see what you're doing.
* Torque: Over-tightening spark plugs can damage the threads in the engine block. Under-tightening can lead to leaks and misfires. Consult your owner's manual for the correct torque specification.
* Coil Pack Damage: Be very careful not to damage the coil packs during removal and installation. They are somewhat fragile.
* Photography: Before starting, it's highly recommended to take pictures of the coil pack locations and how they connect. This will help immensely during reassembly.
If you're not comfortable performing this repair yourself, it's best to take your vehicle to a qualified mechanic. Incorrectly installed spark plugs can damage your engine.
