What are the reasons for diesel engine abnormal noise?
The general abnormal sound of diesel engine mainly comes from the sound of moving parts in the process of motion, combustion and air leakage. The main abnormal sound source comes from the following reasons:
(1) Because of natural wear, the fit clearance of moving parts is too large, such as the clearance between piston and cylinder, and the clearance between crankshaft bush and crankshaft journal produces knocking noise.
(2) Because of poor lubrication and worsening wear, the mating clearance of the moving parts increases rapidly and makes abnormal noises beyond the limit clearance of their use, or because of poor lubrication, the burned and damaged moving parts make abnormal noises, such as crankshaft bearing and connecting rod bearing.
(3) Loose connection bolts of some moving parts cause impact noise, such as flywheel bolts and connecting rod bolts.
(4) The valve clearance is too small to bend the valve push rod, or the tappet body is stuck in the cylinder body tappet hole, which makes the rocker and the valve, the valve push rod and the valve adjustment bolt or the valve push rod and the tappet body make a knock abnormal sound.
(5) Some parts are damaged and abnormal sound occurs, such as broken piston ring, broken valve spring, loose idle gear bushing, etc.
(6) Because of the excessive clearance between piston pin and connecting rod bushing, the loose connecting rod bushing and the failure of piston pin spring to fall in place, the moving parts of piston pin make a knocking sound.
(7) Loose locking nut of valve adjusting bolt, loosen adjusting bolt of valve, excessive clearance of valve, knocking sound of valve push rod and tappet body, adjusting bolt of valve, etc.
(8) The seat ring of the valve is loosened to make the seat and cylinder head of the valve knock or leak with the valve.
(9) As a result of sudden explosion and premature combustion, as well as improper sealing of cylinder gaskets, metal knocking and air leakage (fluffy sound) occur in diesel engines.
(10) Damage of connecting steel sheet of diesel fuel injection pump.