Home › Forums › General Discussion › Had very interesting Spark plug Failure, maybe this info could help others › Reply To: Had very interesting Spark plug Failure, maybe this info could help others
That looks bad, difficult to tell much but it sort of looks like the spark plug was not properly tightened so backed out during use.
Once they come loose then the spark plug heat transfer path to the cylinder head is compromised so the spark plug overheats, electrodes start to glow and erode, then pre-ignition sets in under engine load.
Looks like that one pulled the top threads out of the alloy cylinder head on it way to freedom.
What does the piston top look like? With the spark plug looking like that the piston top might look like the surface of the moon. I have seen similar in automotive engines where the piston top ring land was actually crushed down tight onto the top ring preventing proper ring function.
If they need to remove the cylinder head post some pictures of the piston top and combustion chamber.