Spark Plug: Testing and Inspection

Spark Plug Inspection




1. 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




2. Do not adjust the gap of platinum tip plugs (A), replace the spark plug if the gap is out of specification.




3. Replace the plug at the specified interval, or if the center electrode is rounded (A). Use only the spark plugs listed.