Before You Begin:
* Safety First: Disconnect the negative battery terminal to prevent accidental shorts or shocks.
* Gather Tools: You'll need a socket wrench (likely 5/8" or 13mm), a spark plug socket with a rubber insert (to prevent damaging the plugs), extensions, possibly a universal joint or wobble extension to reach the plugs at an angle, and a torque wrench.
* Protective Gear: Wear safety glasses to protect your eyes from potential debris.
General Steps (Consult your repair manual for specifics):
1. Access: This is the most challenging part. You likely need to remove parts to get a clear shot at the rear plugs. This might include:
* Intake Manifold: In many cases, at least part of the intake manifold may need to be removed or loosened to gain sufficient access. This involves disconnecting various hoses and sensors.
* Fuel Injectors: You might need to disconnect and possibly remove the fuel injectors on the rear bank of the engine to get enough clearance. Be extremely careful working around fuel injectors and fuel lines.
* Other Components: Various other components like wiring harnesses, vacuum lines, and possibly even the engine's upper engine cover may need to be moved aside.
2. Remove the Spark Plugs: Once you have sufficient access, carefully remove the spark plug wires (one at a time, noting which cylinder each wire connects to). Use the spark plug socket to remove the spark plugs.
3. Install New Spark Plugs: Install the new spark plugs, making sure to hand-tighten them first before using the socket wrench. Use the torque wrench to tighten them to the manufacturer's specified torque (consult your repair manual for the correct torque value). Over-tightening can damage the engine block.
4. Reassembly: Carefully reinstall all the components you removed in the reverse order. Double-check that all hoses, wires, and sensors are properly connected. Reconnect the spark plug wires, making sure each wire is securely connected to the correct cylinder.
5. Reconnect Battery: Connect the negative battery terminal.
6. Start Engine: Start the engine and listen for any unusual sounds or rough running. If there are issues, double-check all your connections.
Important Considerations:
* Gap: New spark plugs may need to be gapped correctly. Consult your repair manual or the spark plug packaging for the proper gap.
* Torque: Use a torque wrench to tighten the spark plugs to the manufacturer's specification. This prevents damage to the spark plug threads and the cylinder head.
* Repair Manual: A repair manual specific to your 1999 Pontiac Grand Am GT V6 is crucial. It will provide detailed instructions, diagrams, and torque specifications to ensure you do the job correctly and avoid damage.
If you're not comfortable performing this task yourself, it's best to take your vehicle to a qualified mechanic. This is a more involved job than changing spark plugs on many vehicles, and improper execution can lead to engine damage.
