Spark Plug Molten Insulator Nose
SPARK PLUG MOLTEN INSULATOR NOSE
After removing a spark plug the electrodes at the tip can tell you a lot about your cars condition, and what kind of environment the spark plugs have been working in. Reading a spark plug can help identify many different issues.
If the insulator nose of the spark plug is molten, or the electrodes are strongly singed, it means the spark plugs worked at a very high temperature. This can be caused by improper heat range (the spark plug for the given engine is too hot), the spark plug was over torqued during installation, or a technical defect of the engine.