626 1999-2001

Spark Plugs

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Inspection



Inspect the electrodes and ceramic insulator.

Burned or worn electrodes may be caused by:



Advanced ignition timing
 
Loose spark plug
 
Plug heat range too hot
 
Insufficient cooling
 

Fouled plug may be caused by:



Retarded ignition timing
 
Oil in combustion chamber
 
Incorrect spark plug gap
 
Plug heat range too cold
 
Excessive idling/low speed running
 
Clogged air cleaner element
 
Deteriorated ignition coils
 

Do not adjust the gap of platinum tip plugs; replace the spark plug if the gap is out of specification. Refer to the tune up specification chart for the spark plug gap for your vehicle.

  1. Replace the plug at the specified interval or if the center electrode is rounded.
  2.  
  3. Apply a small quantity of anti-seize compound to the plug threads, and screw the plugs into the cylinder head finger-tight.
  4.  

Removal & Installation



2.0L (Fs) Engine

Specific to:

Mazda 626 1999-2002

When you're removing spark plugs, work on one at a time. Don't start by removing the plug wires all at once, because, unless you number them, they may become mixed up. Take a minute before you begin and number the wires with tape.

  1. Disconnect the negative battery cable, and if the vehicle has been run recently, allow the engine to thoroughly cool.
  2.  
  3. Carefully twist the spark plug wire boot to loosen it, and then pull upward and remove the boot from the plug. Be sure to pull on the boot and not on the wire, otherwise the connector located inside the boot may become separated.
    NOTE
    Remove the spark plugs when the engine is cold, if possible, to prevent damage to the threads. If removal of the plugs is difficult, apply a few drops of penetrating oil or silicone spray to the area around the base of the plug, and allow it a few minutes to work.

  4.  
  5. Using a spark plug socket that is equipped with a rubber insert to properly hold the plug, turn the spark plug counterclockwise to loosen and remove the spark plug from the bore.
    WARNING
    Be sure not to use a flexible extension on the socket. Use of a flexible extension may allow a shear force to be applied to the plug. A shear force could break the plug off in the cylinder head, leading to costly and frustrating repairs.

  6.  

To install:

  1. Carefully thread the plug into the bore by hand. If resistance is felt before the plug is almost completely threaded, back the plug out and begin threading again. In small, hard to reach areas, an old spark plug wire and boot could be used as a threading tool. The boot will hold the plug while you twist the end of the wire and the wire is supple enough to twist before it would allow the plug to crossthread.
    WARNING
    Do not use the spark plug socket to thread the plugs. Always carefully thread the plug by hand or using an old plug wire to prevent the possibility of crossthreading and damaging the cylinder head bore.

  2.  
  3. Carefully tighten the spark plug. If the plug you are installing is equipped with a crush washer, seat the plug, then tighten about 1 / 4 turn to crush the washer. If you are installing a tapered seat plug, tighten the plug to specifications provided by the vehicle or plug manufacturer.
  4.  
  5. On apply a small amount of silicone dielectric compound to the end of the spark plug lead or inside the spark plug boot to prevent sticking, then install the boot to the spark plug and push until it clicks into place. The click may be felt or heard, then gently pull back on the boot to assure proper contact.
  6.  

2.5L (Kl) Engine

Specific to:

Mazda 626 1999-2002

When you're removing spark plugs, work on one at a time. Don't start by removing the plug wires all at once, because, unless you number them, they may become mixed up. Take a minute before you begin and number the wires with tape.

  1. Disconnect the negative battery cable, and if the vehicle has been run recently, allow the engine to thoroughly cool.
  2.  
  3. Carefully twist the spark plug wire boot to loosen it, then pull upward and remove the boot from the plug. Be sure to pull on the boot and not on the wire, otherwise the connector located inside the boot may become separated.
    NOTE
    Remove the spark plugs when the engine is cold, if possible, to prevent damage to the threads. If removal of the plugs is difficult, apply a few drops of penetrating oil or silicone spray to the area around the base of the plug, and allow it a few minutes to work.

  4.  
  5. Using a spark plug socket that is equipped with a rubber insert to properly hold the plug, turn the spark plug counterclockwise to loosen and remove the spark plug from the bore.
    WARNING
    Be sure not to use a flexible extension on the socket. Use of a flexible extension may allow a shear force to be applied to the plug. A shear force could break the plug off in the cylinder head, leading to costly and frustrating repairs.

  6.  

To install:

  1. Carefully thread the plug into the bore by hand. If resistance is felt before the plug is almost completely threaded, back the plug out and begin threading again. In small, hard to reach areas, an old spark plug wire and boot could be used as a threading tool. The boot will hold the plug while you twist the end of the wire and the wire is supple enough to twist before it would allow the plug to crossthread.
    WARNING
    Do not use the spark plug socket to thread the plugs. Always carefully thread the plug by hand or using an old plug wire to prevent the possibility of crossthreading and damaging the cylinder head bore.

  2.  
  3. Carefully tighten the spark plug. If the plug you are installing is equipped with a crush washer, seat the plug, then tighten about 1 / 4 turn to crush the washer. If you are installing a tapered seat plug, tighten the plug to specifications provided by the vehicle or plug manufacturer.
  4.  
  5. On apply a small amount of silicone dielectric compound to the end of the spark plug lead or inside the spark plug boot to prevent sticking, then install the boot to the spark plug and push until it clicks into place. The click may be felt or heard, then gently pull back on the boot to assure proper contact.
  6.  

 
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