Here's a general overview:
Tools You'll Need:
* Spark plug socket: A deep well socket, typically 5/8" (16mm), specifically designed for spark plugs. A universal joint is highly recommended to make access easier.
* Wrench: To fit the spark plug socket. A ratchet is best, but a breaker bar might be needed for stubborn plugs.
* Spark plug gap tool: To check and adjust the gap if necessary (though pre-gapped plugs are common).
* Gloves: To protect your hands.
* New spark plugs: Use the correct type and heat range specified in your owner's manual. Don't use the wrong ones!
* Penetrating oil (like PB Blaster): Highly recommended to spray on the plugs before attempting to remove them. Let it sit for at least 15-20 minutes to work.
* Jack and jack stands: Essential for safe and convenient access to the engine compartment. Never work under a car supported only by a jack.
* Wheel chocks: For added safety.
* Shop rags or paper towels: To clean up oil or debris.
Procedure:
1. Safety First: Disconnect the negative (-) terminal from the battery. Place the car on a level surface, engage the parking brake firmly, and use wheel chocks. Jack up the car safely and securely using jack stands.
2. Locate Spark Plugs: The spark plugs are located on top of the engine. Access will be somewhat limited, so using a jack to slightly raise the front of the car may provide better access.
3. Remove the Coil Packs (if applicable): The 1999 Chrysler LHS likely uses coil-on-plug ignition. You'll need to carefully remove the coil packs that sit on top of the spark plugs. These are usually held in place by bolts or clips. Be careful not to damage the coil packs or their electrical connections. Sometimes a gentle twisting motion can free them.
4. Apply Penetrating Oil: Generously spray penetrating oil onto each spark plug. Let it sit for at least 15-20 minutes (longer is better). This helps loosen the plugs and prevents breakage.
5. Remove the Spark Plugs: Use the spark plug socket and wrench to carefully remove each spark plug. Go slowly and steadily; don't force it. If a plug is extremely difficult to remove, you may need to use a breaker bar, but be very cautious not to strip the threads.
6. Inspect the Old Spark Plugs: Note the condition of the old spark plugs. This can help diagnose any engine problems.
7. Check and/or Adjust the Gap (if necessary): If your new plugs aren't pre-gapped, use the spark plug gap tool to set the gap to the manufacturer's specification found in your owner's manual.
8. Install the New Spark Plugs: Carefully thread the new spark plugs into place by hand, being sure to not cross-thread them. Once they're snug, use the spark plug socket and wrench to tighten them to the proper torque specification. Do not overtighten.
9. Replace Coil Packs: Reinstall the coil packs, ensuring they are securely fastened.
10. Reconnect the Battery: Reconnect the negative (-) battery terminal.
11. Lower the Vehicle: Carefully lower the car using the jack.
12. Start the Engine: Start the engine and listen for any unusual noises. Check for any leaks.
Important Considerations:
* Torque Specifications: The torque specifications for your spark plugs are critical. Over-tightening can damage the engine block, while under-tightening can lead to misfires. Consult your owner's manual or a reliable repair manual for the correct torque.
* Thread Damage: If you strip the threads in the cylinder head while removing or installing the spark plugs, it's a serious problem that requires professional attention.
* Coil Pack Damage: Be extremely careful with the coil packs as they are somewhat delicate.
This is a general guide. If you are unsure about any part of this process, it's best to seek professional help from a qualified mechanic. Improperly installed spark plugs can cause significant engine damage.
