Premature Electrode Wear - Preignition Damage

Spark Plug Inspection:

^ Preignition damage is caused by excessive combustion chamber temperature. First, the center electrode dissolves and the ground electrode dissolves somewhat later. Insulators appear relatively deposit free.

^ Determine if the spark plug has the correct heat range rating for the engine, or if ignition timing is over advanced. Also determine if other operating conditions are causing engine overheating. The heat range rating refers to the operating temperature of a particular type spark plug. Spark plugs are designed to operate within specific temperature ranges depending upon the thickness and length of the center electrode and porcelain insulator.