Tools You'll Need:
* Socket set: Specifically, you'll need a socket that fits your spark plugs (likely 5/8" but double-check your owner's manual). A deep well socket is highly recommended to avoid rounding the spark plug.
* Spark plug socket extension: This will give you the reach needed to access the plugs.
* Wrench (optional): To loosen the coil packs (some people can do this by hand).
* Ratchet: To turn the socket.
* New spark plugs: Make sure you get the correct type and heat range for your engine. Consult your owner's manual or a parts store for the correct specification.
* Gloves: To protect your hands.
* Penetrating oil (optional): If you suspect the plugs might be stuck. Apply this several hours before starting the job.
* Torque wrench (highly recommended): To ensure the new plugs are tightened to the correct specification. Over-tightening can damage the threads. Your owner's manual should specify the torque value.
* Shop towels or rags: To keep things clean.
Procedure:
1. Safety First: Disconnect the negative terminal of your battery. This prevents accidental shorts and protects you from electrical shock.
2. Access the Engine: Locate the spark plugs. They're typically on the top of the engine, but access might be somewhat restricted. You may need to remove parts to get good access, this varies based on equipment. Consult a repair manual for diagrams or videos showing exactly where the plugs are located relative to other components. Some models have the coil packs mounted directly over the plugs.
3. Remove the Coil Packs (if applicable): Many 3.5L V6 Chryslers have coil packs secured over each spark plug. Usually, they're held in place by clips or bolts. Carefully disconnect the electrical connector from each coil pack before removing it. This usually involves a simple push and release on the connector. Then gently remove the coil pack.
4. Remove the Spark Plugs: Carefully use the spark plug socket and ratchet to remove the old spark plugs. Go slow and steady to avoid stripping the threads. If a plug is stuck, apply penetrating oil and let it sit for a few minutes before trying again. A gentle back-and-forth rocking motion can help break loose a stuck plug.
5. Inspect the Old Spark Plugs: Examine the old spark plugs for wear and tear. The condition can indicate potential problems with your ignition system.
6. Install the New Spark Plugs: Carefully install the new spark plugs by hand until they're snug. Do not overtighten by hand. Use the spark plug socket and ratchet to tighten them to the correct torque specification (found in your owner's manual or a repair manual). Over-tightening can easily damage the aluminum engine block threads. A torque wrench is essential here.
7. Replace the Coil Packs (if applicable): Reinstall the coil packs, ensuring the electrical connectors are securely attached.
8. Reconnect the Battery: Reconnect the negative battery terminal.
9. Start the Engine: Start your engine and listen for any unusual noises. If everything is okay, let the engine run for a few minutes to allow it to warm up.
10. Check for Leaks: Inspect around the spark plug boots and the coil packs for any signs of leaks or loose connections.
Important Considerations:
* Repair Manual: A repair manual specific to your 1999 Chrysler LHS 3.5L V6 is highly recommended. It will provide detailed diagrams and torque specifications. Online resources like Haynes or Chilton offer these.
* Gap: Sometimes the gap on new spark plugs needs to be adjusted. Check your owner's manual or the spark plug packaging for the correct gap. Use a spark plug gapping tool if necessary.
* Cleanliness: Keep the area around the spark plugs clean to avoid dropping debris into the engine.
If you're not comfortable performing this task yourself, it's best to take your car to a qualified mechanic. Damaging the spark plug threads can lead to costly repairs.
