Tools You'll Need:
* Spark plug socket: A deep, 5/8" spark plug socket (magnetic is highly recommended to avoid dropping the plug into the engine). A swivel socket extension can be incredibly helpful.
* Wrench or ratchet: A socket wrench or ratchet that fits your spark plug socket.
* Extension(s): You'll need at least one extension, possibly two, to reach the plug. A universal joint will also greatly assist in maneuvering the socket.
* Spark plug wire pliers: To remove and reinstall the spark plug wire.
* Penetrating oil (like PB Blaster): Apply this to the spark plug a few hours before attempting removal to help break any corrosion.
* Shop rags or paper towels: To clean up any oil spills or debris.
* Gloves: Protect your hands from grease and grime.
* Optional: Flex-head ratchet or stubby ratchet: These can make a significant difference in tight spaces.
Procedure:
1. Safety First: Disconnect the negative terminal from your battery. This prevents accidental short circuits.
2. Locate the Spark Plug: The driver's side center spark plug is the most inaccessible. You'll have to maneuver your hand and tools around the intake manifold, exhaust manifolds, and other engine components. A flashlight and possibly a mirror will be helpful.
3. Remove the Spark Plug Wire: Use your spark plug wire pliers to carefully remove the wire from the spark plug. Make sure you don't damage the wire or the boot.
4. Apply Penetrating Oil (if needed): If you haven't already, spray penetrating oil onto the spark plug. Let it sit for at least 15-20 minutes, if not the several hours recommended above.
5. Remove the Spark Plug: This is the most challenging part. Use your spark plug socket, extensions, and potentially a universal joint to carefully reach the plug. Go slowly to avoid stripping the plug. You might need to use a combination of wiggling and turning the socket to get it to break free.
6. Clean the Spark Plug Well: Once removed, inspect the old plug. Clean the area around the plug well before installing the new one.
7. Install the New Spark Plug: Carefully install the new spark plug by hand until it is snug. Then use your socket and ratchet to tighten it to the manufacturer's specified torque. Do not overtighten! Refer to your vehicle's repair manual for the correct torque specification.
8. Reconnect the Spark Plug Wire: Securely attach the spark plug wire back onto the new spark plug.
9. Reconnect the Battery: Reconnect the negative battery terminal.
Important Considerations:
* Repair Manual: A factory service manual for your 1999 Chevy Blazer is highly recommended. It will show you the exact location of the spark plug and provide crucial torque specifications.
* Professional Assistance: If you're uncomfortable working on your vehicle yourself, or if you encounter significant difficulty, consider taking your Blazer to a qualified mechanic. This job is often easier when you have more space and tools.
* Broken Spark Plug: If the spark plug breaks off inside the cylinder head, you'll need to take your Blazer to a mechanic to have it removed. This is a much more serious and expensive repair.
This process is inherently challenging. Take your time, be patient, and don't force anything. If you're unsure about any step, it's always best to err on the side of caution and seek professional help.
