Causes of Abnormal Noise in Diesel Engines?

[MaryLee]

Diesel engine abnormal noise is caused by natural wear. Cause one: Moving parts develop excessive clearance due to natural wear, such as the clearance between the piston and cylinder, or between the crankshaft bearing and crankshaft journal, resulting in knocking sounds from the cylinder or bearings. Cause two: Moving parts wear rapidly due to poor lubrication, causing the clearance to quickly exceed the usage limit and produce abnormal noise, or moving parts may burn out and fail due to poor lubrication, resulting in abnormal noise, such as crankshaft bearing noise and connecting rod bearing noise. Cause three: Certain moving part connection bolts become loose, causing impact sounds, such as flywheel bolts or connecting rod bolts loosening and creating noise. Cause four: Excessively small valve clearance causes the valve pushrod to bend, or the tappet to seize in the cylinder block tappet hole, resulting in knocking noises between the rocker arm and valve, valve pushrod and valve adjustment bolt, or valve pushrod and tappet. Cause five: Individual parts may fail and produce abnormal noise, such as broken piston rings, broken valve springs, or loose idler gear bushings.