GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 39358 Spark Plug Socket

Service Precautions

    • Allow the engine to cool before removing the spark plugs. Attempting to remove the plugs from a hot engine may cause the plug to seize, causing damage to the cylinder head threads.
    • Clean the spark plug recess area before removing the plug. Failure to do so can result in engine damage due to dirt or foreign material entering the cylinder head or contamination of the cylinder head threads. Contaminated threads may prevent proper seating of a new plug.
    • Do not install the plugs that are either "hotter" or "colder" than the heat range specified. Using plugs of the wrong heat range can severely damage the engine. Refer to Maintenance Items in Maintenance and Lubrication.

Removal Procedure

  1. Turn OFF the ignition switch.
  2. Notice: Twist the spark plug boot one-half turn in order to release the boot. Pull on the spark plug boot only. Do not pull on the spark plug wire or the wire could be damaged.

  3. Remove the spark plug wires and boots. Label the spark plug wires.
  4. Notice: Use the J 39358 or the equivalent. Failure to do so could cause cracking of the insulator and arcing inside the plug, resulting in engine misfire.

  5. Remove the spark plugs using the J 39358 .
  6. Inspect each plug for wear and for gap.

Installation Procedure

    Notice: Be sure plug threads smoothly into cylinder head and is fully seated. Use a thread chaser if necessary to clean threads in cylinder head. Cross-threading or failing to fully seat spark plug can cause overheating of plug, exhaust blow-by, or thread damage. Follow the recommended torque specifications carefully. Over or under-tightening can also cause severe damage to engine or spark plug.

  1. Install the spark plugs.
  2. Tighten
    Tighten the spark plugs to 30 N·m (22 lb ft) in a new cylinder head and 20 N·m (14 lb ft) in a used head.

  3. Install the wire and the boot assemblies.