Quick Reference Table For Troubleshooting - Komatsu 4D98 Series Shop Manual

2. Troubleshootimf
2. TROUBLESHOOTING
2.1 Quick Reference Table for Troubleshooting
The following table summarizes the general trouble symptoms and their causes. If any trouble symptom occurs,
take corrective action before it develops into a serious problem so as not to shorten the engine service life.
Trouble symptom
2 Exhaust smoke
0
z
Corrective action
P
Cause
8
8
g
.rn
I?
Improper clearance of intake/exhaust valve 00
0 0 0 0
Adjust the valve clearance. (See 3.5 in Chapter 3.)
Compression leakage from valve seat 0 0 0 0
0 0 0 0
Lap the valve seat. (See 4.2(6) in Chapter 4.)
Seizure of intake/exhaust valve
0 00 0 0 0
00 0 0 0
Correct or replace.
Blowout from cylinder head gasket
0 0 0 Replace the gasket. (See 4.2(2) - @h Chapter 4.)
Seized or broken piston ring
0 0 0 0 0 0 0 00 00 0
Replace the piston ring. (See 4.4(2) - 0, @ in Chapter 4.)
Worn piston ring, piston or cylinder
0 0 0 0 00 0
See 4.4(5)-(5.1). (5.4) and
Perform honing and use oversize parts. in chapter 4.
(6)
Seized crankpin metal or bearfng 00
0 000
0
Repair or replace.
Improper arrangement of piston ring joints
0 0 0 0 Correct the ring joint positions. (See 4.4 (4)-6 in Chapter 4.)
E Reverse assembly of piston rings 0 0
0 0
Reassemble 4.4 in correctly. (See (4)-6 Chapter 4.)
g Worn crankpin and bearing
journal
0 0 000 0
Measure and replace. (See 4.4 (5)-(5.2) - @ in Chapter 4.)
6
E Loosened connecting rod bolt 0 0 0
Tighten to the specified torque. (See 4.4 (4)-2 in Chapter 4.)
z Foreign matter trapped in combustion chamber
0 0
0 0
Disassemble and repair.
Excessive gear backlash 0
Adjust gear meshing. (See 4.3 (4)-2 in Chapter 4.)
Worn intake/exhaust valve guide
0 0 0 Measure and replace. (See 4.2 (5)-(5.2) and (7) in Chapter 4.)
Defective governor
0 0000
Make adjustment. (See 3.8 in Chapter 3.)
Improper open/close timing of intake/
0 0000 0 Adjust the valve clearance. (See 3.5 in Chapter 3.)
exhaust valves
Starting failure
insufficient Poorex- g
engine output haust color -z
Fouled blower
$j Waste gate malfunction
g Worn floating bearing
::
P
3
0 0
0 0
0 0
Wash the blower.
Disassemble and inspect.
Disassemble and inspect.
2-l