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    2007 Jeep Compass

    Spark Plugs

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    Inspection



    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    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.

    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. Proper torque is especially important in the case of aluminum cylinder heads.

    When replacing the spark plug and ignition coil cables, route the cables correctly and secure them in the appropriate retainers. Failure to route the cables properly can cause the radio to reproduce ignition noise. It could also cause cross ignition of the spark plugs and/or cause a short circuit in the cables to a ground.

    Chipped Electrode Insulator

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    A chipped electrode insulator usually results from bending the center electrode while adjusting the spark plug electrode gap. Under certain conditions, severe detonation can also separate the insulator from the center electrode. Spark plugs with this condition must be replaced.

    Click image to see an enlarged view

    Fig. Chipped insulation (3) around center electrode (2) demands spark plug replacement

    Cold Fouling/Carbon Fouling

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    Cold fouling is sometimes referred to as carbon fouling. The deposits that cause cold fouling are basically carbon. A dry, black deposit on one or two plugs in a set may be caused by sticking valves or defective spark plug cables. Cold (carbon) fouling of the entire set of spark plugs may be caused by a clogged air cleaner element or repeated short operating times (short trips).

    Click image to see an enlarged view

    Fig. Normal operation with tan or light gray deposits (1). Cold fouling/carbon fouling with dry, black deposits (2), (3)

    Electrode Gap Bridging

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    Electrode gap bridging may be traced to loose deposits in the combustion chamber. These deposits accumulate on the spark plugs during continuous stop-and-go driving. When the engine is suddenly subjected to a high torque load, deposits partially liquefy and bridge the gap between electrodes. This short circuits the electrodes. Spark plugs with electrode gap bridging can be cleaned using standard procedures.

    Click image to see an enlarged view

    Fig. Deposits (2) bridging gap between ground electrode (1) and center electrode (3)

    Normal Operation

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    Under normal operating conditions, there may be deposits present on the spark plug that are light tan or slightly gray in color. This is evident with most grades of commercial gasoline. A good spark plug should have no evidence of electrode burning.

    Some fuel refiners in several areas of the United States have introduced a manganese additive (MMT) for unleaded fuel. During combustion, fuel with MMT causes the entire tip of the spark plug to be coated with a rust colored deposit. This rust color can be misdiagnosed as being caused by coolant in the combustion chamber. Spark plug performance may be affected by MMT deposits.

    Click image to see an enlarged view

    Fig. Normal operation with tan or light gray deposits (1). Cold fouling/carbon fouling with dry, black deposits (2), (3)

    Oil or Ash Encrusted

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    If one or more spark plugs are oil or oil ash encrusted, evaluate engine condition for the cause of oil entry into that particular combustion chamber.

    Click image to see an enlarged view

    Fig. Oil or ash encrustation on electrodes

    Pre-Ignition Damage

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    Pre-ignition damage is usually caused by excessive combustion chamber temperature. The center electrode dissolves first and the ground electrode dissolves somewhat later. Insulators appear relatively deposit free. Determine if the spark plug has the correct heat range rating for the engine. Determine if the ignition timing is over advanced or if other operating conditions are causing engine overheating. The heat range rating refers to the operating temperature of a particular type of spark plug. Spark plugs are designed to operate within specific temperature ranges which depend upon the thickness and length of the center electrodes and porcelain insulator.

    Click image to see an enlarged view

    Fig. Ground (1) and center (2) electrode dissolving

    Scavenger Deposits

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    Fuel scavenger deposits may be either white or yellow. They may appear to be harmful, but this is a normal condition caused by chemical additives in certain fuels. These additives are designed to change the chemical nature of deposits and decrease spark plug misfire tendencies. Notice that accumulation on the ground electrode and shell area may be heavy, but the deposits are easily removed. Spark plugs with scavenger deposits can be considered normal in condition and can be cleaned using standard procedures.

    Click image to see an enlarged view

    Fig. White or yellow deposits form on ground (1) or center (2) electrodes

    Spark Plug Overheating

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    Overheating is indicated by a white or gray center electrode insulator that also appears blistered. The increase in electrode gap will be considerably in excess of 0.001 inch per 2,000 miles of operation. This suggests that a plug with a cooler heat range rating should be used. Over advanced ignition timing, detonation, and cooling system malfunctions can also cause spark plug overheating.

    Click image to see an enlarged view

    Fig. Blistered white or gray center electrode insulator (1)

    Wet Fouling Or Gas Fouling

    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    A spark plug coated with excessive wet fuel or oil is wet fouled. In older engines, worn piston rings, leaking valve guide seals or excessive cylinder wear can cause wet fouling. In new or recently overhauled engines, wet fouling may occur before break-in (normal oil control) is achieved. This condition can usually be resolved by cleaning and reinstalling the fouled plugs.

    Removal & Installation



    Specific to:

    Jeep Compass 2007-2009

    Jeep Patriot 2007-2009

    Each individual spark plug is located under an individual ignition coil. The ignition coil must be removed in order to access the spark plug.

    1. Before servicing the vehicle, refer to the Precautions Section.
    2.  
    3. Remove the ignition coil. Refer to Ignition Coil, removal & installation.
    4.  
    5. Remove the spark plug using a suitable spark plug socket with a rubber or foam insert.

      Click image to see an enlarged view

      Fig. Using a suitable spark plug socket and socket extension to remove each spark plug

    6.  

    To install:

    1. Inspect the condition of the spark plug. Replace if necessary.
      WARNING
      Handle the spark plugs with care. Do not drop or force the spark plugs into the wells, damage to the electrodes and/or porcelain body may occur. Always start each spark plug by hand in order to avoid cross-threading the spark plug in the cylinder head. Always tighten spark plugs to the specified torque. Too much, or not enough torque, will cause damage to the cylinder head and/or spark plug and may lead to poor engine performance.

    2.  
    3. Install the spark plug and start threading it by hand. Tighten the spark plugs to 20 ft. lbs. (27 Nm).
    4.  
    5. Install the ignition coil to the spark plug. Tighten the mounting bolts to 80 inch lbs. (9 Nm).
    6.  
    7. Connect the negative battery cable.
    8.  

     
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