Before You Begin:
* Safety First: Disconnect the negative (-) battery terminal. This prevents accidental shorts and protects your electrical system.
* Gather Supplies: You'll need the correct spark plugs (check your owner's manual or a parts store for the correct type and gap), a spark plug socket (usually 5/8" or 13/16" depending on the engine, double-check!), a ratchet, extension(s), possibly a universal joint for easier access, a wire brush (to clean the plug wells), a torque wrench (crucial to avoid damaging the threads), and possibly some penetrating oil (like PB Blaster). Gloves are also recommended.
* Consult a Repair Manual: A Haynes or Chilton repair manual specific to your year and engine is invaluable. It will show you precisely where the plugs are located, the proper torque specifications, and other helpful tips.
General Steps:
1. Locate the Spark Plugs: The location varies by engine. Consult your repair manual for precise locations. Generally, they are on top of the engine, under plastic covers or coil packs.
2. Remove any Covers or Coil Packs: Carefully remove any plastic engine covers or coil packs that might be obstructing access to the spark plugs. These often use clips or bolts. If using coil packs, note their order and position before removing them.
3. Clean the Plug Wells: Use a wire brush to remove any dirt, debris, or oil from around the spark plug wells. This prevents debris from falling into the cylinders.
4. Remove the Spark Plugs: Use the appropriate spark plug socket and ratchet to carefully remove each spark plug. If they're stubborn, apply penetrating oil and let it soak for a while before trying again. Avoid cross-threading! Turn the socket counterclockwise.
5. Inspect the Old Spark Plugs: Examine the old plugs for wear and tear. This can help diagnose potential engine problems.
6. Install the New Spark Plugs: Carefully install the new spark plugs, ensuring they are threaded in straight. Do not overtighten! Use a torque wrench and tighten to the manufacturer's specified torque (found in your repair manual). Overtightening can easily strip the threads.
7. Reinstall Coil Packs/Covers: Carefully reinstall any coil packs or plastic covers in their original positions.
8. Reconnect the Battery Cable: Reconnect the negative (-) battery terminal.
9. Start the Engine: Start the engine and check for any misfires or unusual sounds.
Important Considerations:
* Engine Size: The exact procedure will vary slightly depending on your engine.
* Torque Specifications: Using a torque wrench is crucial. Overtightening can damage the threads in the cylinder head.
* Gap: The gap on your new spark plugs might need to be adjusted to the manufacturer's specifications. You'll need a spark plug gapping tool for this.
* Professional Help: If you're uncomfortable performing this task, it's best to take your vehicle to a qualified mechanic.
This is a general overview. Always refer to a repair manual specific to your 1999 Chevy Silverado 1500 and engine size for detailed instructions and torque specifications. Improperly installed spark plugs can lead to serious engine damage.
