Mechanical Gas Fuel System G5.9, G8.3, G855 – Master Repair Manual 013-016   Spark Plugs (Non Shielded)

Remove

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NOTE: Shown throughout this procedure is the QSK19G engine. Although different in appearance, the procedure remains the same.

Disconnect the spark plug wire (1) from the ignition coil and remove the spark plug adapter (2).

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 CAUTION 

Do not let the spark plug fall into its well. Damage to the insulator can result. If the spark plug falls into the well, replace it with a new spark plug.

Use a 13/16 inch magnetic socket to remove the spark plug for standard ignition systems.

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Clean and Inspect for Reuse

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 WARNING 

When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

Spark plugs must always be kept clean. Never touch the porcelain of the spark plug. If the porcelain becomes dirty, it must be cleaned before installation. Cleaning can be done with 100 percent isopropyl alcohol with no additives and a clean cloth.

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Inspect the spark plug for the following problems:

  1. Insulator flashover
  2. Electrode deposits or fouling
  3. Worn or missing electrode.

If a spark plug exhibits any of these problems, the spark plug must be replaced.

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Inspect the spark plug for the following problems:

  1. Cracked insulator
  2. Electrode misalignment
  3. Corona marks.

If a spark plug exhibits any of these problems, the spark plug must be replaced.

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Install

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 CAUTION 

Do not force a feeler gauge into the spark plug gap. This will damage the precious metal electrodes and shorten the spark plug life.

The spark plug can be serviced up to a maximum of three times.

Always replace the spark plug gasket whenever the spark plug is removed from the cylinder head.

Always inspect the gap of new spark plugs.

Application Spark Plug Gap
G/GTA5.9, G/GTA8.3, G/GTA855, GTA14, GTA19, GTA38, GTA50 0.508 mm [0.020 in]
GTA28 0.330 mm [0.013 in]
KTA19GC, KTA38GC Standard Ignition, KTA38GC CSA Ignition 0.381 mm [0.015 in]

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Adjust the gap by bending the ground (side) electrodes using the slots on the gap tool. The ground electrodes must be parallel with the electrode.

 
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NOTE: An equivalent spark plug socket can be substituted if necessary.

The spark plug socket used for installation must also be kept clean. Do not use a spark plug socket with a rubber insert. Rubber inserts can contaminate the spark plugs that you have just cleaned. Use a 13/16-inch magnetic socket to install the spark plug.

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Spark plug threads have anti-seize plating. Anti-seize compound is generally conductive and must not be used on spark plugs.

 
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Check the diameter of the threads prior to installing the spark plugs.

Spark plugs must always be tightened to the correct torque value. On a hot engine, tighten all of the spark plugs hand tight before tightening the first spark plug with a torque wrench. This will allow all of the spark plugs to warm up to the cylinder head temperature prior to tightening.

Tighten the spark plugs.

Torque Value:  38  n.m  [28 ft-lb]

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 CAUTION 

Never use Cummins Lubriplate™ in or on a spark plug adapter boot. Lubriplate™ is a conductor and its use can lead to spark plug flashover, resulting in engine damage.

Cummins Inc. recommends the following dielectric grease:

  • Dupont Krytox 205, Dupont Krytox 206, or Poli-Si-PST-508, Cummins Part Number 3164956.

Apply a pea-sized amount of dielectric lubricant to the spark plug wire o-ring prior to installation. The approved dielectric grease is Cummins Part Number 3164956 or Dupont Krytox 205. This adds to the dielectric seal of the rubber boot and reduces the possibility of the boot melting onto the spark plug.

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Install the spark plug adapter (2).

Install the spark plug wire (1) onto the ignition coil.

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Last Modified:  20-Jul-2006