What are the phenomena and causes of crankshaft axial movement noise?

[Ramona]

Phenomena and causes of crankshaft axial movement noise can be divided into two situations: axial and radial. Axial phenomena and causes: Excessive axial clearance causes vehicle jerking during startup, sometimes accompanied by metallic impact sounds. Diagnosis involves using a pry bar under the vehicle to check for play at the crankshaft pulley. The root cause is typically excessive wear of crankshaft thrust washers requiring replacement. Radial phenomena and causes: Metallic impact sounds and engine vibration occur during acceleration/deceleration. Using a stethoscope (automotive diagnostic stethoscope or 2-3 foot long copper pipe/iron rod), listen near the engine bottom. Subsequent inspection involves checking engine oil for metal particles - 90% probability indicates excessive crankshaft bearing clearance causing abnormal noise. For precise diagnosis under favorable conditions, removing the oil pan provides more accurate assessment.