The characteristics of the loaders piston pin noise are: the noise is more obvious when turning from idle speed to medium speed operation; the period (frequency) of the sound changes with the rise and fall of the engine speed. When the fuel injection time is advanced, the sound is more obvious and clear. After the front loader engine temperature rises, the noise is generally not weakened, and sometimes it is noticeably strengthened. Use the “cylinder-breaking method” test, the sound is weakened or disappeared.