P17. . The spot that appears between the insulator and the metallic castle is caused by gas leakage?

It is not a spot caused for leakage emptying, but for the effect corona (spot corona).
 

 

When removing a spark plug, frequently observes a dark spot close to the metallic castle, which seems to be the effect of the flow of combustion gases.


This spot is the oil particle result in suspension in air that adheres in the surface of the insulator for the effect of the high tension. This condition does not affect the income of the spark plug.

 

Corona Spot

 
 
NOTE

• Ocurrence of the effect Corona

The electric chain ticket provokes the sprouting of an electromagnetic field in the region of the insulator. This electromagnetic field attracts the suspended oil particles in air that are in return of the surface of the insulator, which adheres to exactly propitiating the formation of the spot.

• Corona effect