Common faults in camshafts include abnormal wear, abnormal noise, and breakage, and abnormal wear and tear often occur before abnormal noise occurs.
(1) The camshaft is located at the end of the engine lubrication system, so the lubrication situation is not optimistic. If the oil pump has insufficient oil supply pressure due to excessive use time, or the lubricating oil passage is blocked, the lubricating oil cannot reach the camshaft, or the bearing cap tightening bolt tightening torque is too large, so that the lubricating oil cannot enter the camshaft clearance. Causes abnormal wear of the camshaft.
(2) Abnormal wear of the camshaft causes an increase in the clearance between the camshaft and the bearing housing, and axial displacement occurs when the camshaft moves, resulting in abnormal noise. Abnormal wear can also cause an increase in the clearance between the drive cam and the hydraulic tappet, which can occur when the cam is combined with the hydraulic tappet, resulting in abnormal noise.
(3) The camshaft sometimes has serious faults such as breakage. Common causes are hydraulic tappet fragmentation or severe wear, severe lubrication, poor camshaft quality, and camshaft timing gear breakage.
(4) In some cases, the failure of the camshaft is caused by human factors, especially when the engine is repaired, the camshaft is not properly disassembled. For example, when the camshaft bearing cap is disassembled, it is strongly tapped with a hammer or pressed with a screwdriver, or when the bearing cap is installed, the position of the bearing cap is mismatched, so that the bearing cap does not match the bearing housing, or the tightening torque of the bearing cap fastening bolt is too large. When installing the bearing cap, pay attention to the direction arrow and position number on the surface of the bearing cap, and tighten the bearing cap fastening bolt with a torque wrench in strict accordance with the specified torque.