Series 50 – Section 15.10 Spark Plugs

Section 15.10
Spark Plugs

The condition of the spark plug determines the high voltage level and is the single most important component of the ignition system. The size of the electrode gap, conditions of the electrodes, and the amount of deposits on the electrode all affect the life of the plug. The electrodes of the spark plug are made from platinum or iridium which will minimize electrode wear.‪

The spark plug gap can be regapped if the wear and amount of deposits are low. If either condition is excessive, replace the spark plug. For engine model 6047-TKG8 measure the spark plug gap using a 0.381 mm (0.015 in.) feeler gage. Effective with engine serial number 04R0045632 model 6047-MKG8 measure the spark plug gap using a 0.254 mm (0.010 in.) feeler gage.‪

Note: Servicing of the spark plugs should take place while the engine is cool. This will facilitate easier removal of the spark plugs and reduce the possibility of the plug sticking in the spark plug insert contained in the cylinder head; this also ensures the correct torque and eliminates damage to the spark plug and gasket during installation of the plugs.

Section 15.10.1
Removal of Spark Plug

Remove the spark plugs from the cylinder head as follows:‪

1. Disconnect the ignition wires from the ignition boots.
2. Remove the ignition boots from the spark plug wells by rotating the boot until the boot slots clear the retainer tangs.
3. Remove the plug using a 5/8 in. thin wall spark plug socket and appropriate extensions.

Section 15.10.1.1
Cleaning of Spark Plug Terminal, Ceramic Insulation, and Socket Area

Clean the spark plug terminal, ceramic insulation, and spark plug socket as follows:‪

EYE INJURY ‪
To avoid injury from flying debris when using compressed air, wear adequate eye protection (face shield or safety goggles) and do not exceed 276 kPa (40 psi) air pressure.‪

1. Remove dirt and debris with compressed air.
2. Remove oil and grease deposits.
3. Inspect the spark plug.

Section 15.10.1.2
Inspection of Spark Plug

Inspect the spark plug as follows:‪

1. For engine model 6047-TKG8 measure the spark plug gap using a 0.381 mm (0.015 in.) feeler gage. Effective with engine serial number 04R0045632 model 6047-MKG8 measure the spark plug gap using a 0.254 mm (0.010 in.) feeler gage.
   1. If the spark plug gap measured is not to specifications, re-gap the plug and use again. Refer to "15.10.2 Installation of Spark Plug" .
   2. If the spark plug gap is within specifications, use the spark plug again. Refer to "15.10.2 Installation of Spark Plug"
2. Visually check the spark plugs for excessive deposits and condition of the electrode.
   1. If the spark plug has excessive deposits and electrode wear, replace the spark plug. Refer to "15.10.2 Installation of Spark Plug" .
   2. If the spark plug has no deposits nor excessive electrode wear, use the spark plug again. Refer to "15.10.2 Installation of Spark Plug" .

Section 15.10.2
Installation of Spark Plug

Install the spark plug as follows:‪

1. Install the spark plug using a 5/8 in. thin wall socket and appropriate extensions. Torque the spark plug to 35 - 41 N·m (26-30 lb·ft).
2. Install the ignition boot. Refer to "15.5.2 Installation of Ignition Boot" .
3. Install the ignition harness. Refer to "15.3.2 Installation of Ignition Wire Harness" .