Tools You'll Need:
* Spark plug socket: This is a special socket designed for spark plugs, usually with a rubber insert to grip the plug without damaging it. The size is typically 5/8" (16mm) for a Ford Expedition, but double-check your owner's manual to be sure.
* Spark plug socket extension: This allows you to reach the plugs, especially the rear ones which can be difficult to access.
* Wrench (optional but recommended): A ratchet or breaker bar can provide extra leverage if the plugs are stubborn.
* Needle-nose pliers (optional): Useful for grabbing and removing old spark plug wires.
* Shop rags or paper towels: To keep the engine bay clean.
* Dielectric grease (optional but recommended): For applying to the spark plug threads to help with removal next time and prevent corrosion.
* Torque wrench (highly recommended): To ensure the new spark plugs are tightened to the correct specification. Over-tightening can damage the spark plug and cylinder head. Consult your owner's manual for the correct torque specification.
* Owner's manual: Always consult your owner's manual for specific instructions and torque specifications for your vehicle.
Steps:
1. Safety First: Disconnect the negative (-) battery cable to prevent accidental shorts or damage.
2. Locate the Spark Plugs: The spark plugs are located on top of the engine, one for each cylinder (typically 8 cylinders on a V8 Expedition). They're usually fairly easy to spot, and your owner's manual will show their location.
3. Disconnect the Spark Plug Wires: Carefully remove the spark plug wires, one at a time. Gently pull straight up on the wire boot. If they're difficult to remove, use needle-nose pliers to gently grip the boot and pull it off. Take note of which wire goes to which spark plug so you can reinstall them correctly. Some people like to mark them with masking tape and a number.
4. Remove the Spark Plugs: Using the spark plug socket and extension, carefully remove each spark plug. Turn the socket counter-clockwise to loosen. Be careful not to drop the spark plug into the cylinder. If a plug is particularly stubborn, use a wrench on the socket for extra leverage. Avoid using excessive force, as you could damage the threads. If you're really struggling, consider using penetrating oil (like PB Blaster) and letting it sit for a while before trying again.
5. Inspect the Old Spark Plugs: Examine the old spark plugs for signs of wear, fouling, or damage. This can help diagnose potential engine problems.
6. Install New Spark Plugs (if replacing): Before installing new spark plugs, carefully clean the threads in the cylinder head with a clean brush or compressed air, making sure no debris is left behind. Then, apply a small amount of dielectric grease to the threads of the new spark plug. Screw the new spark plugs in by hand, until snug. Then, using the spark plug socket and a torque wrench, tighten the plugs to the manufacturer's specified torque. Do not over-tighten.
7. Reconnect the Spark Plug Wires: Reattach the spark plug wires to their respective plugs, ensuring a secure connection.
8. Reconnect the Battery Cable: Reconnect the negative (-) battery cable.
Important Considerations:
* Access: Access to the rear spark plugs can be challenging. You may need to use a flexible extension or swivel socket to reach them.
* Cross-threading: Be extremely careful not to cross-thread the spark plugs when installing them. If you feel resistance, stop and re-align the plug before continuing.
* Cleanliness: Keep the engine bay clean to prevent debris from falling into the cylinders.
If you're uncomfortable performing this task yourself, it's best to take your Expedition to a qualified mechanic. Improper installation can cause significant engine damage.
