Solutions For Engine Abnormal Noise, Vibration and Smoke

Fault features

Possible cause

correction

There is rhythmic and light slapping noise at cylinder head.

Valve spring broken, push rod bent, tappet sleeve wear or valve damaged.

Replace the damaged parts and adjust the valve clearance according to the process in 5.3.

There is low, uniform and rhythmic slapping noise at cylinder head during running and collision can be felt when nipping the nuts of the cylinder head cover.

Valve collided with piston.

Remove the cylinder head cover, find out the collision cause, and adjust the valve clearance. If necessary, check if wrong piston(s) is used.

There is abnormal noise at front cover, collision noise can be heard when reducing speed suddenly.

Too big gear backlash due to tooth wear.

Adjust the tooth clearance, and replace the gear according to the wear condition.

There is noise like “Zhi Zhi” at the cylinder head, which is caused by dry friction.

Lack of lube oil between rocker-arm adjusting screw and push rod.

Remove the cylinder head cover, and check and find out the cause.

There is rhythmic and louder noise at cylinder head.

Valve clearance too large.

Check and adjust the valve clearance according to the process in 5.3.

There is abnormal collision noise from the turbocharger.

Poor lubrication due to blocked oil passage leads to the blade(s) bent because of bearing wear.

Disassemble and check whether the bearing is worn out and the blade is bent.

Make replacement if necessary. Clean the oil inlet and outlet passages to ensure smooth oil flow.