Common failures of camshafts include abnormal wear, abnormal noise, and fracture. Abnormal wear and tear symptoms often appear before abnormal noise and fracture occur.
The camshaft is almost at the end of the engine lubrication system, so the lubrication situation is not optimistic. If the oil supply pressure of the oil pump is insufficient due to the long-term use, or the lubricating oil passage is blocked so that the lubricating oil cannot reach the camshaft, or the tightening torque of the bearing cap fastening bolts is too large, the lubricating oil cannot enter the camshaft clearance, and the Causes abnormal wear of the camshaft.
Abnormal wear of the camshaft will cause the gap between the camshaft and the bearing seat to increase, and the axial displacement will occur when the camshaft moves, resulting in abnormal noise. Abnormal wear will also cause the gap between the drive cam and the hydraulic tappet to increase, and the cam will collide when combined with the hydraulic tappet, resulting in abnormal noise.
Serious failures such as breakage of camshafts sometimes occur. Common causes include cracked or severely worn hydraulic tappets, severe poor lubrication, poor camshaft quality, and cracked camshaft timing gears.