74
(VIII) Abnormal Sound during Operation of Diesel Engine
Fault Characteristics & Causes
Elimination Approaches
1. Fuel injection is too early; there is rhythmed and clear
metallic rapping in cylinder.
1. Adjust the advance angle of fuel supply.
2. Fuel injection is delayed too much; there is dull and
indistinct sound in cylinder.
2. Adjust the advance angle of fuel supply.
3. Clearance between piston and cylinder is too large so
that there is clash in the cylinder after startup of diesel
engine. The sound will be diminished with warming up of
the engine.
3. Replace the piston or the cylinder liner.
4. Clearance between piston pin and pin hole thereof is
too large. The sound is soft and sharp, which will be
clearer at idle especially.
4. Replace the parts to guarantee the
specified clearance.
5. Clearance between main bearing and connecting rod
bearing is too large so that clash of machine members
can be heard when the speed of diesel engine is
decreased suddenly. The sound is heavy and strong
when the speed is low.
5. Replace the parts to guarantee the
specified clearance.
6. Axial clearance of crankshaft is too large so that clash
of the crankshaft
’
s moving forward and backward can
be heard in case of idle speed.
6. Replace the crankshaft thrust plate to
guarantee the specified clearance.
7. Valve spring is broken; push rod is bent; valve
clearance is too large; splutter or soft and rhythmed
7. Replace the parts, adjust the valve
clearance.
