Ram Truck 1500, 2500 & 3500 (2006-2008)

Spark Plugs

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Inspection



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 small, hand-held wire brush. Do not use a powered wire wheel to clean plugs.

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 (side) 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.

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Fig. Inspect the spark plug to determine engine running conditions



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



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Fig. Removing the boot from the heat shield



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Fig. Checking the spark plug gap with a feeler gauge



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Fig. Adjusting the spark plug gap



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

Removal & Installation



3.7L Engine

Each individual spark plug is located under each ignition coil. Each individual ignition coil must be removed to gain access to each spark plug. Refer to the Ignition Coil Removal & Installation procedure in this section.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove necessary air filter tubing at throttle body.
  4.  
  5. Prior to removing ignition coil, spray compressed air around coil base at cylinder head.
  6.  
  7. Prior to removing spark plug, spray compressed air into cylinder head opening. This will help prevent foreign material from entering combustion chamber.
  8.  
  9. Remove spark plug from cylinder head using a quality socket with a rubber or foam insert. Also check condition of ignition coil O-ring and replace as necessary.
  10.  
  11. Inspect the condition of the spark plugs.
  12.  

To install:


NOTE
Special care should be taken when installing spark plugs into the cylinder head spark plug wells. Be sure the plugs do not drop into the plug wells as electrodes can be damaged.


NOTE
Always tighten spark plugs to the specified torque. Over tightening can cause distortion resulting in a change in the spark plug gap or a cracked porcelain insulator.

  1. Start the spark plug into the cylinder head by hand to avoid cross-threading.
  2.  
  3. Tighten the spark plugs to 20 ft. lbs. (27 Nm).
  4.  
  5. Before installing ignition coil(s), check condition of coil O-ring and replace as necessary. To aid in coil installation, apply silicone to coil O-ring.
  6.  
  7. Install ignition coil(s). Refer to Ignition Coil Removal/Installation in this section.
  8.  

4.7L Engine

Each individual spark plug is located under each ignition coil. Each individual ignition coil must be removed to gain access to each spark plug. Refer to Ignition Coil Removal/Installation.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove necessary air filter tubing at throttle body.
  4.  
  5. Prior to removing ignition coil, spray compressed air around coil base at cylinder head.
  6.  
  7. Prior to removing spark plug, spray compressed air into cylinder head opening. This will help prevent foreign material from entering combustion chamber.
  8.  
  9. Remove spark plug from cylinder head using a quality socket with a rubber or foam insert. Also check condition of ignition coil O-ring and replace as necessary.
  10.  
  11. Inspect the condition of the spark plugs.
  12.  

To install:


WARNING
The 4.7L V-8 engine is equipped with copper core ground electrode spark plugs. They must be replaced with the same type/number spark plug as the original. If another spark plug is substituted, pre-ignition will result.


NOTE
Special care should be taken when installing spark plugs into the cylinder head spark plug wells. Be sure the plugs do not drop into the plug wells as electrodes can be damaged.


NOTE
Always tighten spark plugs to the specified torque. Over tightening can cause distortion resulting in a change in the spark plug gap or a cracked porcelain insulator.

  1. Start the spark plug into the cylinder head by hand to avoid cross-threading.
  2.  
  3. Tighten the spark plugs to 20 ft. lbs. (27 Nm).
  4.  
  5. Before installing ignition coil(s), check condition of coil O-ring and replace as necessary. To aid in coil installation, apply silicone to coil O-ring.
  6.  
  7. Install ignition coil(s).
  8.  

5.7L (MDS) Engine

NOTE
Each individual spark plug is located under each ignition coil. Each individual ignition coil must be removed to gain access to each spark plug.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove necessary air filter tubing at throttle body.
  4.  
  5. Prior to removing the ignition coil, spray compressed air around coil base at cylinder head.
  6.  
  7. Prior to removing spark plug, spray compressed air into cylinder head opening. This will help prevent foreign material from entering combustion chamber.
  8.  
  9. Remove spark plug from cylinder head using a quality socket with a rubber or foam insert. Also check condition of ignition coil O-ring and replace as necessary.
  10.  
  11. Inspect spark plug condition.
  12.  

To install:


NOTE
Special care should be taken when installing spark plugs into the cylinder head spark plug wells. Be sure the plugs do not drop into the plug wells as electrodes can be damaged.


WARNING
Always tighten spark plugs to the specified torque. Over tightening can cause distortion resulting in a change in the spark plug gap or a cracked porcelain insulator.

  1. Start the spark plug into the cylinder head by hand to avoid cross threading.
  2.  
  3. The 5.7L is equipped with torque critical design spark plugs. Do not exceed 15 ft. lbs. Tighten spark plugs to 13 ft. lbs. (18 Nm).
  4.  
  5. Before installing ignition coils, check condition of coil O-ring and replace as necessary. To aid in coil installation, apply silicone to coil O-ring.
  6.  
  7. Install ignition coils.
  8.  

5.7L (SMPI) Engine

Eight of the 16 spark plugs are located under an ignition coil; the other 8 are not. If spark plug being removed is under coil, coil must be removed to gain access to spark plug. Refer to Ignition Coil Removal/Installation.


NOTE
Before removing or disconnecting any spark plug cables, note their original position. Remove cables one-at-a-time. To prevent ignition crossfire, spark plug cables MUST be placed in cable tray (routing loom) into their original position. Refer to Spark Plug Cable Removal for a graphic.


NOTE
Before installing spark plug cables to either the spark plugs or coils, apply dielectric grease to inside of boots.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove necessary air filter tubing at throttle body.
  4.  
  5. Prior to removing ignition coil (if coil removal is necessary), spray compressed air around coil base at cylinder head cover.
  6.  
  7. Prior to removing spark plug, spray compressed air into cylinder head opening. This will help prevent foreign material from entering combustion chamber.
  8.  
  9. Inspect the condition of the spark plugs.
  10.  

To install:


NOTE
Special care should be taken when installing spark plugs into the cylinder head spark plug wells. Be sure the plugs do not drop into the plug wells as electrodes can be damaged.

  1. Start the spark plug into cylinder head by hand to avoid cross-threading aluminum threads. To aid in installation, attach a piece of rubber hose, or an old spark plug boot to spark plug.
    WARNING
    The 5.7L V-8 is equipped with torque critical design spark plugs. Do not exceed 15 ft. lbs. (20 Nm) torque.

  2.  
  3. Tighten the spark plugs to 11-15 ft. lbs. (15-21 Nm).
  4.  
  5. Before installing spark plug cables to either the spark plugs or coils, apply dielectric grease to inside of boots.
  6.  
  7. To prevent ignition crossfire, spark plug cables MUST be placed in cable tray (routing loom) into their original position.
  8.  
  9. Install ignition coil(s) to necessary spark plugs. Refer to Ignition Coil Installation.
  10.  
  11. Install spark plug cables to remaining spark plugs. Remember to apply dielectric grease to inside of boots.
  12.  

 
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