Here's a general outline. Specifics may vary slightly depending on the exact engine (3.1L or 3.8L). Consult a repair manual specific to your vehicle's year and engine for detailed instructions and torque specifications. A Haynes or Chilton manual is a good investment.
Tools You'll Need:
* Socket wrench set: You'll need a socket that fits the spark plug (likely 5/8" or 13/16", check your manual). A ratchet and extension will be helpful for access.
* Spark plug socket: This has a rubber insert to grip the spark plug without damaging the ceramic insulator. A magnetic spark plug socket makes retrieval much easier.
* Wrench for coil wire connectors: Some 1994 Cutlass Supremes used a retaining clip or screw to secure the coil wire connectors.
* New spark plugs: Use the correct type and heat range recommended by the manufacturer (check your owner's manual or a parts store).
* Gloves: To protect your hands from grease and dirt.
* Penetrating oil (optional): If the plugs are stubborn, applying penetrating oil beforehand can help.
* Shop rags: To clean up any spills.
Steps:
1. Locate the Spark Plugs: The spark plugs are located on the top of the engine. You'll need to access them from the engine bay.
2. Disconnect the Coil Wires: Carefully disconnect the spark plug wires from the spark plugs. Take note of which wire goes to which plug so you can reconnect them correctly. Some connectors just pull off, others may have a retaining clip or screw.
3. Remove the Spark Plugs: Using the spark plug socket, carefully loosen and remove each spark plug. Turn counter-clockwise to loosen. If a plug is particularly difficult to remove, use penetrating oil and let it sit for a while before trying again. Don't force it, as you could damage the plug or the threads in the cylinder head.
4. Inspect the Old Spark Plugs: Check the condition of the old plugs. Look for signs of wear, fouling, or damage. This can help diagnose potential engine problems.
5. Install the New Spark Plugs: Screw the new spark plugs into the cylinder head by hand, until they are snug. Then use the spark plug socket and ratchet to tighten them to the correct torque specification. Over-tightening can damage the threads. Again, consult your repair manual for the correct torque specification.
6. Reconnect the Coil Wires: Carefully reconnect the spark plug wires to the new spark plugs, ensuring each wire is securely connected to the correct plug.
7. Reconnect the Battery: Reconnect the negative battery terminal.
8. Start the Engine: Start the engine and check for any misfires or unusual sounds.
Important Considerations:
* Repair Manual: This is highly recommended. Pictures and diagrams will help significantly.
* Torque Specification: Using the correct torque is crucial to prevent damage.
* Gap: Some spark plugs may require a specific gap. Check your new plugs and adjust if necessary using a spark plug gapping tool. This step is usually unnecessary with pre-gapped plugs.
If you're not comfortable performing this task yourself, it's best to take your vehicle to a qualified mechanic. Improperly installed spark plugs can cause engine damage.
