MAINTENANCE MANUAL OF ENGINE
139
7. Abnormal sound from the diesel engine
Fuel supply
advance angle
The fuel supply advance angle is too
big, and there is rhythmic metallic
knocking sound.
Adjust the fuel supply advance
angle to 16°±1°
The fuel drips from fuel injector or the
needle valve is stuck.
Repair or replace (Refer to Sec-
tion 6, Chapter 3 of this Part)
The valve clearance is too big, and there
is clear and rhythmic knocking.
Adjustment (Refer to Section 1,
Chapter 3 of this Part)
The piston is in contact with the valve.
Adjustment (Refer to Section 1,
Chapter 3 of this Part)
The cylinder head thickness is insuffi-
cient, and the piston contacts the cylin-
der head.
Change the cylinder head gasket.
Valve spring,
valve push
rod, and valve
tappet
The valve spring is broken, the valve
push rod is bent, and the valve tappet is
worn, resulting in a slight knocking
from the valve mechanism.
Change the damaged part (Refer
to Chapter 1, Part II)
Piston and
cylinder liner
The clearance between piston and cyl-
inder liner is too big, but such sound is
weakened as the diesel engine tempera-
ture rises.
Repair or change the piston, cyl-
inder liner, piston ring and piston
pin (Refer to Chapter 1 and Chap-
ter 2, Part II).
Connecting
rod bearing
shell
The connecting rod bearing shell clear-
ance is too big. When the speed de-
creases suddenly, a heavy and strong
whomp can be heard.
Change the connecting rod bear-
ing shell bushing (Refer to Chap-
ter 2, Part II).
Connecting
rod bushing
and piston pin
The clearance between connecting rod
bushing and piston pin is too big. Such
sound is slightly sharp, especially clear
during idling.
Change the connecting rod and
piston pin bush (Refer to Chapter
2, Part II)
The wear of the crankshaft thrust plate
will lead to excessive axial clearance,
and it is possible to hear knocking pro-
duced from forward and backward
movement of the crankshaft during
idling.
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