37
Abnormal noise during engine operation
Possible causes
Remedies
Incorrect injection timing or
injector stuck and high frequency
knock noise in cylinder.
Check the injector; replace the needle valve
precision pair if necessary. Check the fuel
injection advance angles, if it changes, adjust to
the prescription.
Clash due to too large clearance
between piston and cylinder
sleeve
Check the wear of the piston and cylinder
sleeve, replace them if necessary.
Clash due to too large clearance
between connecting rod bearing
bushing, main bearing bushing
and journal
Check if the bearing bushing and crankshaft are
much worn out, replace or press in the oversized
bearing bushing if necessary.
Knock due to valve touching
cylinder
Check and adjust the valve clearance. Inspect
the valve timing for the overhauled engine
Clash due to too large crankshaft
axial clearance
Check the wear of the thrust plate
，
replace it if
necessary.
Abnormal knock due to valve
spring crack
Stop immediately to check and replace the
damaged parts.
Too large valve clearance and
heavy noise around cylinder head
Adjust the valve clearance
