Komatsu 170-3 Series, Руководство по ремонту, Страница: 160 / 454

12-104
170-3 SERIES
TROUBLESHOOTING METHOD OF USING TROUBLESHOOTING CHART
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• Example of troubleshooting when exhaust gas is black
Let us assume that [Clogged air cleaner] is taken to be the cause of black exhaust gas. Three symptoms
have causal relationship with this problem: [Exhaust gas slowly became black], [Power slowly became
weaker], and [Dust indicator is red].
If we look from these three symptoms to find the causes, we find that there is a relationship with five causes.
Let us explain here the method of using this causal relationship to pinpoint the most probable cause.
S-7 Exhaust smoke is black (incomplete combustion)
General causes why exhaust smoke is black
•
Insufficient intake of air
• Defective condition of fuel injection
• Excessive injection of fuel
: Possible causes (judging from Questions and Check items)
: Most probable causes (judging from Questions and Check items)
: Possible causes due to length of use (used for a long period)
: Items to confirm the cause.
Legend
Questions
Clean Replace Replace Adjust Correct Replace Replace Replace Replace Replace Replace Replace
Check items
T
roubleshooting
Remedy
Clogged air cleaner element Seized turbocharger
, interference
Defective contact of valve and valve seat Improper adjustment of valve clearance Leakage of air between turbocharger and cylinder head Crushed, clogged muf
fler
W
orn piston ring, cylinder liner
Defective fuel pump Defective injector Cut, worn injector O-ring Failure timing rail pressure sensor Defective timing rail actuator (Marked )
Causes
Inspect air cleaner directly
When turbocharger is rotated by hand, it is found to be heavy
When compression pressure is measured, it is found to be low
Inspect valve clearance directly
When muffler is removed, exhaust sound improves
Inspect between turbocharger and cylinder head directly
When pressure at outlet port of fuel pump is measured, it is found to be low
When temperature of injector of each cylinder is measured, there are some cylinders that are low
Abnormality in timing rail pressure sensor system is indicated ( 1)
Inspect sensor directly (Output voltage)
Inspect actuator directly (Resistance and filter for clogging)
Confirm recent repair history
Degree of use of machine Operated for long period
Color of exhaust gas
Suddenly became black
Gradually became black
Blue under light load
Non-specified fuel is being used
Engine oil must be added more frequently
Power was lost
Suddenly
Gradually
Dust indicator is red
Muffler is crushed
Leakage of air between turbocharger and head, loose clamp
When exhaust manifold is touched immediately after starting engine, temperature of some cylinders is low
Noise of interference is heard from around turbocharger
Clanging sound is heard from around cylinder head
Exhaust noise is abnormal
Engine pickup is poor and combustion is irregular
Blow-by gas is excessive
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