Montana, Silhouette, Venture 2000-2005

Spark Plugs

Print

Inspection & Gapping



  1. Inspect the terminal post for damage
  2.  
  3. Inspect for a bent or broken terminal post
  4.  
  5. Test for a loose terminal post by twisting and pulling the post. The terminal post should NOT move.
  6.  
  7. 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.
  8.  
  9. Inspect for the following conditions:
  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 causes 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 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.
  28.  
  29. A rattling sound indicates internal damage
  30.  
  31. A loose center electrode reduces the spark intensity.
  32.  
  33. Inspect for bridged electrodes. Deposits on the electrodes reduce or eliminates the gap.
  34.  
  35. Inspect for worn or missing platinum pads on the electrodes if equipped
  36.  
  37. Inspect for excess fouling
  38.  
  39. 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
  40.  
  41. Normal operation--Brown to grayish-tan with small amounts of white powdery deposits are normal combustion by-products from fuels with additives.
  42.  
  43. Carbon fouled--Dry, fluffy, black carbon, or soot caused by the following conditions:

    Rich fuel mixtures
     
    Leaking fuel injectors
     
    Excessive fuel pressure
     
    Restricted air filter element
     
    Incorrect combustion
     
    Reduced ignition system voltage output
     
    Weak coils
     
    Worn ignition wires
     
    Incorrect spark plug gap
     

  44.  
  45. Excessive idling or slow speeds under light loads can keep spark plug temperatures so low that normal combustion deposits may not burn off.
  46.  
  47. 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.
  48.  

Check the plugs for deposits and wear. If they are not going to be replaced, clean the plugs thoroughly. Remember that any kind of deposit will decrease the efficiency of the plug. Plugs can be cleaned on a spark plug cleaning machine, which can sometimes be found in service stations, or you can do an acceptable job of cleaning with a stiff brush. If the plugs are cleaned, the electrodes must be filed flat. Use an ignition points file, not an emery board or the like, which will leave deposits. The electrodes must be filed perfectly flat with sharp edges; rounded edges reduce the spark plug voltage by as much as 50%.

Check spark plug gap before installation. The ground electrode (the L-shaped one connected to the body of the plug) must be parallel to the center electrode and the specified size wire gauge (please refer to the Tune-Up Specifications chart for details) must pass between the electrodes with a slight drag.


NOTE
NEVER adjust the gap on a used platinum type spark plug.

Always check the gap on new plugs as they are not always set correctly at the factory. Do not use a flat feeler gauge when measuring the gap on a used plug, because the reading may be inaccurate. A round-wire type gapping tool is the best way to check the gap. The correct gauge should pass through the electrode gap with a slight drag. If you're in doubt, try one size smaller and one larger. The smaller gauge should go through easily, while the larger one shouldn't go through at all. Wire gapping tools usually have a bending tool attached. Use that to adjust the side electrode until the proper distance is obtained. Absolutely never attempt to bend the center electrode. Also, be careful not to bend the side electrode too far or too often as it may weaken and break off within the engine, requiring removal of the cylinder head to retrieve it.

Click image to see an enlarged view

Fig. Inspect the spark plug to determine engine running conditions



Click image to see an enlarged view

Fig. A variety of tools and gauges are needed for spark plug service



Click image to see an enlarged view

Fig. Checking the spark plug gap with a feeler gauge



Click image to see an enlarged view

Fig. Adjusting the spark plug gap



Click image to see an enlarged view

Fig. If the standard plug is in good condition, the electrode may be filed flat-WARNING: do not file platinum plugs

Removal & Installation




NOTE
Observe the following service precautions:



Allow the engine to cool before removing the spark plugs. Attempting to remove spark plugs from a hot engine can cause the spark plugs to seize. This can damage the cylinder head threads.
 
Clean the spark plug recess area before removing the spark plug. Failure to do so can result in engine damage due to dirt or foreign material entering the cylinder head, or in contamination of the cylinder head threads. Contaminated threads may prevent proper seating of the new spark plug.
 
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.
 

  1. Turn the ignition OFF.
  2.  
  3. If you are replacing the engine right bank (rear) spark plugs, rotate the engine for service access
  4.  
  5. Remove the spark plug wires from the spark plugs.
  6.  
  7. Remove the spark plugs from the engine.
  8.  

To install:


NOTE
It is important to check the gap of all new and reconditioned spark plugs before installation. Pre-set gaps may have changed during handling. Use a round wire feeler gauge to be sure of an accurate check, particularly on used plugs. Installing plugs with the wrong gap can cause poor engine performance and may even damage the engine. Gap the spark plugs to the specifications.


NOTE
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.


NOTE
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  1. Install the spark plugs.
  2.  
  3. If the spark plugs are installed into a new cylinder head, tighten the spark plugs to 15 lb-ft (20 Nm). If the spark plugs are installed into an existing cylinder head, tighten the spark plugs to 11 lb-ft (15 Nm).
  4.  
  5. Install the spark plug wires to the spark plugs.
  6.  

3.5L Engine
  1. Replacing the engine left bank spark plugs requires, rotating the engine for access as follows:
    1. Remove the throttle body air inlet duct.
    2.  
    3. Set the park brake.
    4.  
    5. Shift the transaxle into Neutral.
    6.  
    7. Remove the engine mount strut bolts. Swing the engine mount struts aside.
    8.  
    9. Install the Engine Tilt Strap J-41131.
    10.  
    11. Pull on the engine in order to rotate the engine forward.
    12.  
    13. Tighten the strap.
    14.  

  2.  
  3. Remove the spark plug wires from the spark plugs.
  4.  
  5. Remove the spark plugs from the engine.
  6.  

To install:

  1. Install the spark plugs to the engine and tighten to 11 ft. lbs. (15 Nm). If installing the spark plugs into a new cylinder head, tighten to 15 ft. lbs. (20 Nm).
  2.  
  3. Install the spark plug wires to the spark plugs.
  4.  
  5. If the engine was rotated for access, return engine to original position.
  6.  

3.9L Engine
  1. Remove the air intake assembly.
  2.  
  3. Remove the intake manifold.
  4.  
  5. Remove the left side spark plug wires.
  6.  
  7. Rotate the engine for access as follows:
    1. Set the parking brake.
    2.  
    3. Shift the transaxle into neutral.
    4.  
    5. Remove the engine mount strut bolts. Swing the engine mount struts aside.
    6.  
    7. Install the Engine Tilt Strap J-41131.
    8.  
    9. Pull on the engine in order to rotate the engine forward.
    10.  
    11. Tighten the strap.
    12.  

  8.  
  9. Remove the right side spark plug wires.
  10.  
  11. Remove the spark plugs.
  12.  

To install:

  1. Install the spark plugs to the engine and tighten to 11 ft. lbs. (15 Nm).
  2.  
  3. Install the spark plug wires to the spark plugs.
  4.  
  5. If the engine was rotated for access, return engine to original position.
  6.  
  7. The remainder of the installation is the reverse order of removal.
  8.  

 
label.common.footer.alt.autozoneLogo