1. The document provides instructions for removing and installing various starting motor, alternator, fuel injection pump, nozzle holder, water pump, thermostat, engine front seal, and engine rear seal assemblies on Komatsu PC27-45MRX excavators. 2. Key steps include disconnecting battery cables, removing mounting bolts and brackets, disconnecting electrical connectors and fluid lines, and noting proper tightening specifications. 3. Reinstallation is the reverse of the removal process, and instructions emphasize adjusting belt tension and refilling fluids as needed.

7. DISASSEMBLY AND ASSEMBLY STARTING MOTOR
REMOVAL OF STARTING
MOTOR ASSEMBLY
PC27MRX, PC30MRX
a Stop the machine on the horizontal ground, then
lower the work equipment completely to the
a
ground and stop the engine.
Disconnect the cable from the negative (-) ter-
minal of the battery.
Remove seat bracket and right and left PPC valve
assembly. For details, see REMOVAL OF SEAT
BRACKET, R.H. AND L.H. PPC VALVE ASSEMBLY.
Disconnect wiring connector (1) (T4).
Remove the boots, then disconnect 2 wires (2).
Remove starting motor assembly (3).
INSTALLATION OF STARTING
MOTOR ASSEMBLY
PC27MRX, PC30MRX
l Carry out installation in the reverse order to re-
moval.
-T-----. lvGiph&-- CWPO6279
30-10
0
PC27 - 45MRX-1

8. DISASSEMBLY AND ASSEMBLY STARTING MOTOR
REMOVAL OF STARTING
MOTOR ASSEMBLY
PC35MRX, PC40MRX, PC45MRX
A .
Disconnect the cable from the negative (-) ter-
minal of the battery.
1. Remove air-conditioner unit assembly.
Ir For operator cabin specification machine only.
2. Remove inspection cover (1) at under of operator’s
seat.
3. Disconnect wiring connector (2).
Ir Wiring connector (T4) : PC35MRX
J, Wiring connector (MIO) : PC40MRX, PC45MRX
4. Remove the boots and disconnect 2 wire (3).
5. Remove starting motor assembly (4).
INSTALLATION OF STARTING
MOTOR ASSEMBLY
PC35MRX, PC40MRX, PC45MRX
l Carry out installation in the reverse order to re-
moval.
PC27 - 45MRX- 1 30-l 1
0

9. DISASSEMBLY AND ASSEMBLY ALTERNATOR
REMOVAL OF ALTERNATOR
ASSEMBLY
PC27MRX, PC30MRX
g Stop the machine on the horizontal ground, then
lower the work equipment completely to the
A
ground and stop the engine.
Disconnect the cable from the negative (-1 ter-
minal of the battery.
1.
2.
3.
4.
5.
6.
Remove the cover (I 1.
Disconnect connector (2) (El) and (3) (E2).
Disconnect water temperature sensor connector
(4) (E7).
Remove adjustment bolt (5).
Loosen mounting bolt, and remove alternator belt
(7). m
Remove mounting bolt (6) and remove the alter-
nator assembly (8).
INSTALLATION OF ALTERNATOR
ASSEMBLY
PC27MRX, PC30MRX
l Carry out installation in the reverse order to re-
moval.
* Adjust the alternator belt. For details, see
TESTING AND ADJUSTING, Testing and ad-
justing alternator belt tension.
.3
.2
CWPO6292
30-l 2
0
PC27 - 45MRX-1

10. DISASSEMBLY AND ASSEMBLY ALTERNATOR
REMOVAL OF ALTERNATOR
ASSEMBLY
PC35MRX
A .
Disconnect the cable from the negative (-1 ter-
minal of the battery.
1.
6.
Remove the right lever stand assembly (I) with
mounting bracket.
Disconnect wiring connector (2) (El,E2).
Disconnect wire (3).
Loosen mounting bolt and adjustment bolt (4).
Remove adjustment bracket (51, then remove fan
belt (6) from pulley. [a
* It is not enable to remove the fan belt from
pulley, after remove adjustment bracket.
-k There are spacers fitted to the adjustment
bolts so be careful not to drop them.
Remove the alternator assembly (7).
+ There are spacers fitted to the mounting bolts
so be careful not to drop them.
INSTALLATION OF ALTERNATOR
ASSEMBLY
PC35MRX
l Carry out installation in the reverse order to re-
moval.
Adjust the alternator belt. For details, see
TESTING AND ADJUSTING, Testing and ad-
justing alternator belt tension.
PC27 - 45MRX- 1 30-l 3
0

11. DISASSEMBLY AND ASSEMBLY ALTERNATOR
REMOVAL OF ALTERNATOR
ASSEMBLY
PC40MRX, PC45MRX
A .
Drsconnect the cable from the negative (-) ter-
minal of the battery.
1. Remove the right side upper cover.
2. Remove the cover (I) between operator’s cab and
hydraulic tank.
3. Disconnect wiring connector (2) (M8, M9).
4. Disconnect wire (3).
5. Loosen mounting bolt and adjustment bolt (4).
6. Remove adjustment bracket (51, then remove fan
belt (6) from pulley. a
* It is not enable to remove the fan belt from
pulley, after remove adjustment bracket.
Sr There are spacers fitted to the adjustment
bolts so be careful not to drop them.
7. Remove the alternator assembly.
* There are spacers fitted to the mounting bolts
so be careful not to drop them.
INSTALLATION OF ALTERNATOR
ASSEMBLY
PC45MRX, PC45MRX
l Carry out installation in the reverse order to re-
moval.
* Adjust the alternator belt. For details, see
TESTING AND ADJUSTING, Testing and ad-
justing alternator belt tension.
30-14
0
PC27 - 45MRX- 1

12. DISASSEMBLY AND ASSEMBLY FUEL INJECTION PUMP
REMOVAL OF FUEL INJECTION
PUMP ASSEMBLY
PC27MRX
A Stop the machine on the horizontal ground, then
lower the work equipment completely to the
g ground and stop the engine.
Disconnect the cable from the negative (-) ter-
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
minal of the battery.
Pull out the fuel control cable pin (I).
Disconnect engine stop solenoid wiring connec-
tor (2) (E3).
Remove lubrication tube (3).
Disconnect fuel supply hose (4).
Disconnect fuel return hose(5).
Ir Spill hose is jointed to fuel return hose.
Disconnect 3 fuel injection tubes (6). m
Remove the cover (7).
Remove the injection mounting nut (8). a
Ir Make sure the impressed mark position.
Remove the drive gear mounting nut (9). m
Be careful not to drop the nut and washer into
the front cover.
Make the matching mark with white paint on
the drive gear and idler gear.
Remove fuel injection pump assembly (IO).
* Using puller 0, push the fuel injection pump
cam shaft and disconnect drive gear, then re-
move fuel injection pump assembly.
* Be careful not to drop the woodruff key into
the case.
PC27 - 45MRX- 1

13. DISASSEMBLY AND ASSEMBLY FUEL INJECTION PUMP
INSTALLATION OF FUEL INJECTION
PUMP ASSEMBLY
PC27MRX
l Carry out installation in the reverse order to re-
moval.
m Sleeve nut : 25.5 f 1.0 Nm I2.6 f 0.1 kgm}
m
* Align the case impressed mark, then tighten
the nut.
m Mounting nut: 3.9f 1.0 Nm IO.4i 0.1 kgm}
113
Ir Align the gear marching marks, then tighten
the nut.
w Mounting nut:
58.8 f 1.0 Nm IS.0 + 0.1 kgm}
30-l 6
0
PC27 - ISMRX- 1

14. DISASSEMBLY AND ASSEMBLY FUEL INJECTION PUMP
REMOVAL OF FUEL INJECTION
PUMP ASSEMBLY
PC30MRX, PC35MRX, PC45MRX
A Stop the machine on the horizontal ground, then
lower the work equipment completely to the
ground and stop the engine.
A Disconnect the cable from the negative (-1 ter-
minal of the battery.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Remove counter weight. For details, see RE-
MOVAL OF COUNTER WHIGHT ASSEMBLY.
Pull out the fuel control cable pin (I) and discon-
nect cable from bracket. m
Ir Check the mounting length, before disconnect
bracket.
Disconnect engine stop solenoid wiring connec-
tor (2).
Ir Wiring connector (E3) :
PC27MRX, PC30MRX, PC35MRX
* Wiring connector (M13) : PC40MRX. PC45MRX
Remove lubrication tube (3).
Disconnect fuel supply hose (4).
Disconnect fuel return hose(5).
* Spill hose is jointed to fuel return hose.
Disconnect 3 fuel injection tubes (6)
Ir PC27MRX, PC30MRX, PC35MRX : 3 tubes
Sr PC40MRX, PC45MRX : 4 tubes
Remove the cover (7).
Remove the injection mounting nut (8). 112
* Make sure the impressed mark..
Remove the drive gear mounting nut (9). m
Be careful not to drop the nut and washer into
the front cover.
Make the matching mark with white paint on
the drive gear and idler gear.
When it is difficult to make the marching mark,
remove radiator l hydraulic cooler assembly.
For details, see REMOVAL OF RADIATOR l HY-
DRAULIC COOLER ASSEMBLY.
Remove fuel injection pump assembly (IO).
Ir Using puller 0, push the fuel injection pump
cam shaft and disconnect drive gear, then re-
move fuel injection pump assembly.
* Be careful not to drop the woodruff key into
the case.
30-17
0
PC27 - 45MRX- 1

15. DISASSEMBLY AND ASSEMBLY FUEL INJECTION PUMP
INSTALLATION OF FUEL INJECTION
PUMP ASSEMBLY
PCSOMR, PC35MR, PC40MR, PC45MR
l Carry out installation in the reverse order to re-
moval.
m
*
m
*
Adjust the fuel control cable. For detail, see
TESTING AND ADUJUSTING, Adjusting fuel
control cable.
Align the case impressed mark, then tighten
the nut.
m Injection pump mounting nut :
20.58 + 0.98 Nm I2.1 * 0.1 kgm}
w
Ir Align the gear marching marks, then tighten
the nut.
QK! Drive gear mounting nut :
63.7 + 4.9 Nm 16.5 + 0.5 kgm}
30-18
0
PC27 - 45MRX- 1

16. DISASSEMBLY AND ASSEMBLY NOZZLE HOLDER
REMOVAL OF NOZZLE HOLDER
ASSEMBLY
PC27MRX
A Stop the machine on the horizontal ground, then
lower the work equipment completely to the
ground and stop the engine.
A Disconnect the cable from the negative (-) ter-
minal of the battery.
1.
2.
Remove air inlet hoses (I) and (2).
Remove the mounting bolt (3) and remove air
cleaner assembly (4).
3. Remove air cleaner mounting bracket (5).
4. Remove fuel injection tube (6). m
5. Disconnect spill hose, then remove retainer (7).
6. Remove nozzle holder assembly (8).
INSTALLATION OF NOZZLE
HOLDER ASSEMBLY
PC27MRX
l Carry out installation in the reverse order to re-
moval.
m
w Sleeve nut : 25.5 + 1.0 Nm (2.6 f 0.1 kgm}
m
B Retainer mounting nut :
3.9 _+1.0 Nm to.4 f 0.1 kgm)
When assembling the nozzle holder, clean the
nozzle holder mount, and check that there is
no dust inside the sleeve before assembling.
PC27 - 45MRX- 1 30-19
0

17. REMOVAL OF NOZZLE HOLDER
ASSEMBLY
PCSOMRX, PC35MRX, PC4OMRX, PC45MRX
g Stop the machine on the horizontal ground, then
lower the work equipment completely to the
negative (-) ter-
1. Remove air inlet hoses (I 1and (2). m
2. Remove the mounting bolt (3) ,then remove air
cleaner assembly (4).
3. Remove air cleaner mounting bracket (5).
4. Remove fuel injection tube (6).
5. Disconnect spill hose (7).
6. Remove retainer (8).
7. Remove nozzle holder assembly (9).
INSTALLATION OF NOZZLE
HOLDER ASSEMBLY
PCSOMRX, PC35MRX, PC40MRX, PC45MRX
l Carry out installation in the reverse order to re-
moval.
DISASSEMBLY AND ASSEMBLY NOZZLE HOLDER
m Intake air hose clamp :
5.9 ? 0.49 Nm {SO + 5 kgcml
m Retainer mounting nut :
4.41 + 0.49 Nm (0.45 + 0.05 kgml
* When assembling the nozzle holder, clean the
nozzle holder mount, and check that there is
no dust inside the sleeve before assembling.
30-20 PC27 - 45MRX- 1

18. DISASSEMBLY AND ASSEMBLY WATER PUMP
REMOVAL OF WATER PUMP
ASSEMBLY
A Stop the machine on the horizontal ground, then
lower the work equipment completely to the
ground and stop the engine.
a Disconnect the cable from the negative (-) ter-
minal of the battery.
1. Remove radiator l oil cooler assembly (1). For de-
tails, see REMOVE OF RADIATOR l HYDRAULIC
COOLER ASSEMBLY.
2. Loosen alternator mounting bolt, then remove al-
ternator belt (2) from alternator pulley. m
3. Remove fan (3) mounting bolt. then remove pul-
ley (4) and alternator belt together.
+ Fan pulley and fan are tighten together.
4. Remove mounting bolt (5), then remove the wa-
ter pump assembly (6). m
INSTALLATION OF WATER
PUMP ASSEMBLY
l Carry out installation in the reverse order to re-
moval.
Ir Adjust the alternator belt tension. For details,
see TESTING AND ADJUSTING, testing and
adjusting alternator belt tension.
w Water pump mounting bolt :
10.78 f 1.96 Nm Il.1 f 0.2 kgm}
l Refilling with water
Add water through water filler to the specified
level. Run the engine to circulate the water
through the system. Then check the water level
by reserve tank again.
PC27 - 45MRX- 1 30-21
a

19. DISASSEMBLY AND ASSEMBLY THERMOSTAT
REMOVAL OF THERMOSTAT
ASSEMBLY
g Stop the machine on the horizontal ground, then
lower the work equipment completely to the
ground and stop the engine.
1. Disconnect radiator inlet hose (I ). m
2. Remove mounting bolt, then remove cover (2).
3. Remove thermostat assembly (3).
IIINSTALLATION OF
THERMOSTAT ASSEMBLY
l Carry out installation in the reverse order to re-
moval.
QFI Radiator inlet hose clamp :
8.8 f 0.5 Nm I90 + 5 kgcml
l Refilling with water
Add water through water filler to the specified
level. Run the engine to circulate the water
through the system. Then check the water level
by reserve tank again.
30-22
0
PC27 - 45MRX-1

20. DISASSEMBLY AND ASSEMBLY ENGINE FRONT SEAL
REMOVAL OF ENGINE FRONT
SEAL
1.
2.
3.
4.
5.
Remove radiator and hydraulic cooler assembly.
For details, see REMOVAL OF RADIATOR HY-
DRAULIC COOLER ASSEMBLY.
Loosen alternator mounting bolt, then remove al-
ternator belt (2) from alternator pulley. m
Remove fan (3) mounting bolt. then remove pul-
ley (4) and alternator belt together.
Ir Fan pulley and fan are tighten together.
Remove bolt (5) and spacer (61, and tighten the
bolt (5) 2 to 4 turns again, then remove crank pul-
ley (7) using puller 0. 112
Remove engine front seal (8). a
INSTALLATION OF ENGINE
FRONT SEAL
l Carry out installation in the reverse order to re-
moval.
Ir Adjust the alternator belt tension. For details,
see TESTING AND ADJUSTING, Testing and
adjusting alternator belt tension.
m Crankshaft pulley mounting bolt :
112.7+~* Nm {11.5+:” kgm}
& Lip of oil seal : Engine oil (EOSO-CD)
w / 1 CWPO6406
I
CWPO6407
PC27 - 45MRX- 1 30-23
0

21. DISASSEMBLY AND ASSEMBLY
ENGINE REAR SEAL
REMOVING OF ENGINE REAR
SEAL
1. Remove the damper assembly. For details, see
REMOVAL OF DAMPER ASSEMBLY
2. Remove the flywheel (1). m
3. Remove the seal case (2). a
* Since the seal case has notches on the both
ends, prize the case with screwdriver to re-
move it.
4. Remove the engine rear seal (3) from the seal
case. m
CLPO2630
30-24
0
PC27 - 45MRX- 1

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23. DISASSEMBLY AND ASSEMBLY ENGINE REAR SEAL
INSTALLATION OF ENGINE
REAR SEAL
. Carry out installation in the reverse order to re-
moval.
,Q& Seal mounting face of seal case and oil seal
lip : Engine oil (E030XD)
Ir Press fit the oil seal until it comes to the same
level as the seal case.
6 Seal case mounting face :
Gasket sealant (LG-7)
* Tighten the flywheel mounting bolts in the or-
der shown in the drawing on the right.
w Flywheel mounting bolt :
85.75 f 2.45 Nm 18.75 k 0.25 kgm)
* After installing the flywheel, check it for fa-
cial runout and radial runout with dial gauge
0.
l Facial runout : 0.20mm max.
l Radial runout : 0.20mm max.
PC27 - 45MRX-1 30-25
0

24. DISASSEMBLY AND ASSEMBLY CYLINDER HEAD
REMOVAL OF CYLINDER HEAD
ASSEMBLY
a Stop the machine on the horizontal ground, then
lower the work equipment completely to the
a
ground and stop the engine.
Disconnect the cable from the negative (-) ter-
1.
2.
3.
4.
Remove seat bracket, right and left PPC valve as-
sembly. For details, see REMOVAL OF SEAT
BRACKET, R.H. AND L.H. PPC VALVE ASSEMBLY.
(PC27MRX, PC30MRX)
Remove seat bracket assembly. For details, see
REMOVAL OF SEAT BRACKET ASSEMBLY.
(PC35MRX)
Remove floor frame assembly. For details, see RE-
MOVAL OF FLOOR FRAME ASSEMBLY.
(PC40MRX, PC45MRX)
Remove counterweight assembly. For details, see
REMOVAL OF COUNTERWEIGHT ASSEMBLY.
5. Disconnect air intake hose (21, (3).
6. Remove air cleaner (4).
7. Remove air cleaner bracket (5).
8. Disconnect fuel filter (6) from cylinder head.
9. Disconnect fuel injection tube (7).
10.
11.
12.
Disconnect heater wire (8) from intake manifold.
Disconnect spill hose (9).
Disconnect wiring connector (IO) from intake
manifold.
Sr Wiring connector (E3) :
PC27MRX, PC30MRX, PC35MRX
Ir Wiring connector (M13) : PC40MRX, PC45MRX
minal of the battery.
I
30-26
a
PC27 - 45MRX- 1

25. DISASSEMBLY AND ASSEMBLY CYLINDER HEAD
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
Disconnect bracket (11) mounting bolt from en-
gine block, then remove muffler (12).
t Before disconnect mounting bolt, remove
muffler from exhaust manifold.
Remove exhaust manifold (13).
Disconnect wiring connector (14).
* Wiring connector (E7):
PC27MRX, PC30MRX, PC35MRX
Ir Wiring connector (P2): PC40MRX, PC45MRX
Remove alternator adjusting bracket (15). m
Remove radiator, hydraulic cooler assembly. For
details, see REMOVAL OF RADIATOR, HYDRAU-
LIC COOLER ASSEMBLY.
Remove alternator belt (17) and fan (18).
Remove water pump mounting bolt, then remove
water pump assembly (19).
Remove cylinder head cover (20).
Disconnect spill hose (21), then remove nozzle
holder assembly (22) after remove retainer. m
Remove rocker arm assembly. m
* Loosen the locknut, then loosen the adjust-
ment screw 2 to 3 turns.
Remove push rod (24).
Remove cylinder head mounting bolts, then re-
move cylinder head assembly (26). m
* Disconnect air intake manifold, after remove
cylinder head.
i8
CWPO6418
PC27 - 45MRX-1 30-27
0