Here's a general guide. Always consult your owner's manual for specifics and torque specifications for your vehicle. Torque is crucial to avoid damaging the threads in the engine block.
Tools You'll Need:
* Spark plug socket: A deep-well socket that fits your spark plugs (usually 5/8" or 13/16"). A quality socket with a rubber insert to grip the plug is highly recommended to prevent rounding off the spark plug.
* Spark plug wrench: A 3/8" drive ratchet or breaker bar is ideal. Extensions might be necessary depending on access.
* Wrench (or pliers): To remove the coil pack wires/boots. Some use a special coil pack tool.
* Torque wrench: Essential to tighten the plugs to the correct specification (found in your owner's manual). Over-tightening is a common mistake.
* New spark plugs: Purchase the correct type and heat range for your engine. Check your owner's manual or a parts store. They may be pre-gapped, but double-check the gap with a feeler gauge.
* Gloves: To keep your hands clean.
* Penetrating oil (like PB Blaster): May help if the plugs are stuck.
* Shop rags: To clean up any spills.
Procedure:
1. Disconnect the battery's negative terminal. This is crucial for safety.
2. Locate the spark plugs: They're located on top of the engine. You'll likely need to remove some plastic covers or shrouds to access them fully. Your owner's manual will show you the location.
3. Remove the coil packs: Most 1999 Explorer Sports have individual coil packs for each spark plug. You'll likely need to unclip or disconnect the electrical connectors and then remove the coil pack itself. These are usually held in place by clips or bolts. Take note of the order of the coil packs before removing them.
4. Clean the area around the spark plugs: Use compressed air or a shop rag to remove any dirt or debris.
5. Remove the old spark plugs: Use your spark plug socket and ratchet to carefully remove the plugs. Be gentle; if a plug is stuck, apply penetrating oil and let it sit for a while before trying again. Turn the socket counter-clockwise.
6. Inspect the old spark plugs: Look for any signs of wear, fouling, or damage. This can indicate issues with your engine.
7. Install the new spark plugs: Carefully install the new spark plugs, ensuring they're seated correctly. Do not force them. Hand-thread them initially then use the socket to tighten them.
8. Tighten the new spark plugs to the correct torque specification: Use your torque wrench to tighten the plugs to the manufacturer's recommended torque. This is VERY important to avoid damaging the threads. Your owner's manual will tell you the correct specification.
9. Reinstall the coil packs: Carefully place the coil packs back in their original positions and secure them. Reconnect the electrical connectors.
10. Reconnect the battery's negative terminal.
11. Start the engine: Listen for any unusual noises.
Important Considerations:
* Gap: If your new spark plugs aren't pre-gapped, you'll need to gap them using a feeler gauge to the manufacturer's specification.
* Torque: Over-tightening spark plugs can strip the threads in the engine block, causing serious damage. Under-tightening can lead to leaks and misfires. Use a torque wrench and follow the specifications in your owner's manual.
* Order: Make sure you install the spark plugs in the correct firing order. Your owner's manual will have this information.
This is a general guide. Always refer to your owner's manual for specific instructions and torque specifications for your 1999 Ford Explorer Sport. If you are unsure about any step, it's best to consult a qualified mechanic.
