DeVille, Eldorado, Seville 1999-2005

Spark Plugs

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Inspection & Gapping



  1. Ensure that the correct spark plug is installed; an incorrect spark plug causes driveability conditions.
  2.  
  3. Ensure that the spark plug has the correct heat range. An incorrect heat range causes the following conditions:

    Colder plugs will result in spark plug fouling.
     
    Hotter plugs can result in pre-ignition and subsequent spark plug or engine damage.
     

  4.  
  5. Inspect for a bent or broken terminal post.
  6.  
  7. Test for a loose terminal post by twisting and pulling the post. The terminal post should NOT move.
  8.  
  9. Inspect the insulator for flashover or carbon tracking, soot. This is caused by the electrical charge traveling across the insulator between the terminal post and ground.
  10.  
  11. Inspect the spark plug boot for damage.
  12.  
  13. Inspect the spark plug recess area of the cylinder head for moisture, such as oil, coolant, or water. A spark plug boot that is saturated results in arcing to ground
  14.  
  15. Inspect the insulator for cracks. All or part of the electrical charge may arc through the crack instead of the electrodes.
  16.  
  17. Inspect side electrode for evidence of improper arcing.
  18.  
  19. Measure the gap between the center electrode and the side electrode terminals. An excessively wide electrode gap can prevent correct spark plug operation.
  20.  
  21. Inspect for the correct spark plug torque. Insufficient torque can prevent correct spark plug operation; an over-torqued spark plug causes the insulator to crack.
  22.  
  23. Inspect for signs of tracking that occurred near the insulator tip instead of the center electrode.
  24.  
  25. Inspect for a broken or worn side electrode.
  26.  
  27. Inspect for a broken, worn, or loose center electrode by shaking the spark plug; a rattling sound indicates internal damage.
  28.  
  29. Inspect for bridged electrodes.
  30.  
  31. Inspect for worn or missing platinum pads on the electrodes, if equipped.
  32.  
  33. Inspect for excessive fouling.
  34.  
  35. Inspect the spark plug recess area of the cylinder head for debris. Dirty or damaged threads can cause the spark plug not to seat correctly during installation.
  36.  
  37. Visually inspect spark plug to determine:

    Normal operation-Brown to grayish-tan with small amounts of white powdery deposits are normal combustion by-products from fuels with additives
     
    Carbon fouled-Dry, fluffy black carbon, or soot
     
    Deposit fouling-Oil, coolant, or additives that include substances such as silicone, very white coating, reduces the spark intensity. Most powdery deposits will not effect spark intensity unless they form into a glazing over the electrode.

    Click image to see an enlarged view

    Fig. Spark plug components identified.

     

  38.  

Removal & Installation



  1. Remove the intake manifold cover (injector sight shield).
    NOTE
    Use care when removing the spark plug boots from the spark plugs. Twist the boot 1 / 2 turn before removing. Pull on the boot only. Do not pull on the wire as this may cause damage to the spark plug wire.

  2.  
  3. Remove the spark plug wire from the spark plug.
  4.  
  5. Remove the spark plug from the cylinder head.
  6.  

To install:


NOTE
Make sure the spark plug is properly gapped before installation.

  1. Install the spark plug into the cylinder head and tighten to 11 ft. lbs. (15 Nm).
  2.  
  3. Install the spark plug boot onto the spark plug.
  4.  
  5. Install the intake manifold cover.
  6.  

  1. Turn the ignition OFF .
  2.  
  3. Remove the ignition coil assembly.
  4.  
  5. Use a Spark Plug Boot Puller in order to remove the spark plug boots from the spark plugs.
    WARNING
     Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.


    NOTE
    Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

  6.  
  7. Remove the spark plugs from the engine.
  8.  

To install:


WARNING
 Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.


WARNING
 Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.


NOTE
Make sure the spark plug is properly gapped before installation.

  1. Install the spark plugs and tighten to 15 ft. lbs. (20 Nm).
  2.  
  3. Install the spark plug boots to the ignition coil assembly.
  4.  

  1. Turn the ignition switch OFF .
  2.  
  3. Remove the ignition coils.
    WARNING
     Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.


    NOTE
    Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

  4.  
  5. Remove the spark plugs from the engine.
  6.  
  7. Inspect the spark plugs.
  8.  

To install:


WARNING
 Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.


WARNING
 Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.


NOTE
Make sure the spark plug is properly gapped before installation.

  1. Install the spark plugs to the engine and tighten to 13-17 ft. lbs. (17-23 Nm).
  2.  
  3. Install the ignition coils.
  4.  

 
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