The crankshaft pulley may have the following faults during use:

1. Wear: Due to long-term friction and friction, the surface of crankshaft pulley may be worn. Wear may lead to poor meshing between pulley and belt, reduce transmission efficiency, and even lead to belt sliding or falling off.

2. Looseness: The fixing bolt or nut of the crankshaft pulley may be loose, resulting in an unstable connection between the pulley and the crankshaft. Looseness will lead to unstable rotation of the pulley, and may even cause the belt to fall off.