Spark Plug: Testing and Inspection

Spark Plug Inspection:

1. Inspect the Electrodes and Ceramic Insulator for:
- Worn or deformed Electrodes.
Improper Gap.
Oil Fouling.
Carbon Deposits.
Cracked Center Electrode Insulator.
- Damaged Gasket.
- Cracked Insulator.

Burned or worn Electrodes may be caused by:
- Advanced Ignition Timing.
- Loose Spark Plug.
- Plug heat range too low.
- Insufficient cooling.

Fouled Plug may be caused by:
- Retarded Ignition Timing.
- Oil in Combustion Chamber.
- Incorrect Spark Plug gap.
- Plug heat range too high.
- Excessive idling/low speed running.
- Clogged Air Cleaner Element.
- Deteriorated Ignition Coil or Ignition Wires.

Checking Gap:

Electrode Gap:

2. Adjust the gap with a suitable gapping tool, and replace the Plug if the center Electrode is rounded as shown.

Spark Plugs / Parts Numbers:

NOTE: Use only the Spark Plugs listed.

3. Apply a small quantity of anti-seize compound to the Plug Threads before installing the plugs.
4. Screw the Plugs into the Cylinder Head finger-tight. Then torque them to 18 N.m (1.8 kg.m, 13 lb.ft).