King Long XMQ6900 Series, Operating Manual

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Common trouble and elimination
6-1
Abnormal noise during engine operation
Possible causes Remedies
1) Connecting rod bearing bushing and
main bearing bushing are worn-out
and clash voice appears in the
crankcase.
1) Dismantle and check the bushing and, if necessary, replace it
and keep the reasonable clearance as required.
2) The Damper is damaged and
invalid.
2) Change components to keep regulated axial clearance
3) The shock absorber is damaged and
ineffective
3) Check and see if the joint bolts are in good conditions, and
change new ones if necessary.
4) The valve knocks on the piston
4) Check and adjust the valve timing.
5) The driving gear is abraded and get
too large gap. There is knocking
sound at the timing gear box cover.
5) Check the gear side clearance and change the gear or not
according to the abrasion situations.
6) Too big clearance between piston and
cylinder and there is knocking sound
at the cylinder wall.
6) Change the piston and use the repairing cylinder liner. Keep the
proper clearance between piston and cylinder.
7) Puff vibration of supercharger
7) Remove the carbon and waste in the compressor channel and
the exhaust channel.
8) The bearing of supercharger is
damaged and the rotor knocks on the
shell
8) Change the supercharger assembly
9) The valve clearance is too large and
there is big noise at the cylinder head.
9) Adjust the valve clearance.