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1. SERVICE MANUAL
COMPACT EXCAVATOR
48Z-1, 51R-1
EN - 9813/6200 - ISSUE 1 - 0 /2016
This manual contains original instructions, verified by
the manufacturer (or their authorized representative).
Copyright 2016 © JCB SERVICE
All rights reserved. No part of this publication may
be reproduced, stored in a retrieval system, or
transmitted in any form or by any other means,
electronic, mechanical, photocopying or otherwise,
without prior permission from JCB SERVICE.
www.jcb.com
Foreword
The Operator's Manual
You and others can be killed or seriously injured
if you operate or maintain the machine without
first studying the Operator's Manual. You must
understand and follow the instructions in the
Operator's Manual. If you do not understand
anything, ask your employer or JCB dealer to
explain it.
Do not operate the machine without an Operator's
Manual, or if there is anything on the machine you
do not understand.
Treat the Operator's Manual as part of the machine.
Keep it clean and in good condition. Replace the
Operator's Manual immediately if it is lost, damaged
or becomes unreadable.
Contents
01 - Machine
03 - Attachments and Options
06 - Body and Framework
09 - Operator Station
12 - Heating, Ventilating and Air-
Conditioning (HVAC)
15 - Engine
18 - Fuel and Exhaust System
21 - Cooling System
27 - Driveline
30 - Hydraulic System
33 - Electrical System
72 - Fasteners and Fixings
75 - Consumable Products
78 - After Sales

2. 15 - Engine
06 - Cylinder Head
00 - General
15 - 27 9813/6200-1 15 - 27
00 - General
Introduction .................................................... 15-27
Technical Data ............................................... 15-28
Check (Condition) .......................................... 15-28
Calibrate ........................................................ 15-29
Remove and Install ....................................... 15-30
Introduction
The cylinder head is located above the cylinders
on top of the crankcase. It closes in the top of the
cylinder, forming the combustion chamber. This joint
is sealed by a cylinder head gasket.
The cylinder head also provides the space for the
passages that feed air and fuel to the cylinder and
allow the exhaust to escape. The cylinder head is
also used to mount the valves (PIL 15-30) and fuel
injectors (PIL 18-18).

3. 15 - Engine
06 - Cylinder Head
00 - General
15 - 28 9813/6200-1 15 - 28
Technical Data
Table 38. Cylinder head gasket
Piston height below
top face of crankcase
Gasket Thickness
+0.35mm to +0.5mm 1.2mm
+0.5mm to +0.6mm 1.3mm
Table 39. Distortion of the cylinder head
Description Data
Distortion of the cylinder
head
0–0.05mm
Maximum service limit 0.12mm
Maximum limit for re-
grinding the cylinder
head
0.15mm
Check (Condition)
1. Make the machine safe. Refer to (PIL 01-03).
2. Get access to the engine. Refer to (PIL 06-06).
3. Remove the cylinder head bolts in the reverse
numerical order. This will prevent distortion of the
cylinder head. Refer to Figure 72.
Figure 72.
12 4 5 13
17
18
1027
918
11 3 6 14
16
15
4. Remove the cylinder head from the engine.
5. Clean the cylinder head thoroughly.
6. Make sure that the contact surface of the cylinder
head and the contact surface of the crankcase
are clean, smooth and flat.
7. Inspect the bottom surface of the cylinder head
for pitting, corrosion and cracks.
8. Inspect the area around the valve seats and the
holes for the fuel injectors.
9. Put the cylinder head on a suitable support.
Figure 73.
A
B
A Cylinder head
B Support
10. Use a straight edge and a feeler gauge to check
the six positions for distortion. Refer to Figure 74.

4. 15 - Engine
06 - Cylinder Head
00 - General
15 - 29 9813/6200-1 15 - 29
Figure 74.
6
1
4
2
5
3
Calibrate
• The dowel pins in the crankcase hold the
cylinder head gasket in the correct position
when the cylinder head is installed. Refer to
Figure 75.
• The stamped marking on the cylinder head
gasket must face upward. This makes sure that
the cylinder head gasket is installed correctly.
Refer to Figure 75.
Figure 75.
A
B
C
A Dowel pins
B Gasket
C Stamped marking
• Before you tighten the bolts, apply clean engine
oil on the threads of the bolts. The bolts must
be tightened to the torque of 101N·m in the
specified numerical sequence only. Refer to
Figure 76.
Figure 76.
12 4 5 13
17
18
1027
918
11 3 6 14
16
15
• Use a straight edge and a feeler gauge to check
the six positions for distortion. Refer to Figure
77.
Figure 77.
6
1
4
2
5
3

5. 15 - Engine
06 - Cylinder Head
00 - General
15 - 30 9813/6200-1 15 - 30
• If you grind the cylinder head, check the valve
depth below the cylinder head face. Refer to
(PIL 15-30).
Remove and Install
CAUTION This component is heavy. It must only
be removed or handled using a suitable lifting
method and device.
Remove
1. Make the machine safe. Refer to (PIL 01-03).
2. Make sure that the engine is safe to work on. If
the engine has been running, let it cool before
you start the service work.
3. Remove the exhaust manifold. Refer to (PIL
18-24).
4. Remove the fuel filter. Refer to (PIL 18-09).
5. Remove the fuel injectors. Refer to (PIL 18-18).
6. Remove the glow plugs. Refer to (PIL 15-80).
7. Remove the rocker shaft and the push rods.
Refer to (PIL 15-42).
8. Remove the cooling pump. Refer to (PIL 21-09).
9. Drain the cooling system. Refer to (PIL 21-00).
10. Gradually loosen the bolts in reverse numerical
order. This will prevent distortion of the cylinder
head. Refer to Figure 78.
Figure 78.
12 4 5 13
17
18
1027
918
11 3 6 14
16
15
11. Remove the bolts from the cylinder head.
12. Carefully lift the cylinder head off the crankcase
with a suitable lifting device.
13. Make sure of the following:
13.1.Do not use a lever to separate the cylinder
head from the crankcase.
13.2.Take care not to damage the machined
surfaces of the cylinder head.
13.3.Avoid contamination of the cylinder bores
with coolant or with debris.
13.4.Place the cylinder head on a surface that
will not scratch the face of the cylinder head.
14. Remove the cylinder head gasket. Retain the old
gasket to help identification.

6. 15 - Engine
06 - Cylinder Head
00 - General
15 - 31 9813/6200-1 15 - 31
15. Make a note of the position of the dowels. Do not
remove the dowels unless they are damaged.
16. If necessary, remove the thermostat from the
cylinder head. Refer to (PIL 21-12).
Figure 79.
A
B
A Bolt
B Cylinder head
Figure 80.
C
C
D
D
C Dowel
D Guide bolt (M11 by 100mm)
Install
1. Clean the mating surfaces of the cylinder head
and the crankcase.
2. Make sure that no debris enters the cylinder
bores, the coolant passages, or the lubricant
passages.
3. Inspect the mating surface of the cylinder head
for distortion. If the mating surface of the cylinder
head is distorted beyond the maximum permitted
limits, replace the cylinder head.
4. Inspect dowels for damage. If necessary, replace
the dowels in the crankcase.
5. Install the guide bolts to the crankcase.
6. Make sure that the new gasket is of the same
thickness as the old gasket.
7. Align the gasket with the guide bolt and the
dowels. Install the gasket onto the crankcase.
8. Lift the cylinder head with a suitable lifting device.
9. Align the cylinder head with the guide bolts on
the crankcase. Install the cylinder head onto the
crankcase.
10. Make sure that the cylinder head is correctly
positioned on the dowels.
11. Remove the guide bolts.
12. Install the bolts to the cylinder head.
13. Tighten the bolts to the correct torque value in
the specified numerical sequence only. Refer to
Figure 78.
14. If removed, install the thermostat to the cylinder
head. Refer to (PIL 21-12).
15. Install the cooling pump. Refer to (PIL 21-09).
16. Install the rocker shaft and the push rods. Refer
to (PIL 15-42).
17. Install the glow plugs. Refer to (PIL 15-80).
18. Install the fuel injectors. Refer to (PIL 18-18).
19. Install the fuel filter. Refer to (PIL 18-09).
20. Install the exhaust manifold. Refer to (PIL 18-24).
Table 40. Torque Values
Item Description Nm
A Bolt 100

7. 15 - Engine
09 - Bedplate
00 - General
15 - 33 9813/6200-1 15 - 33
00 - General
Introduction
The bedplate acts as the main strength component
of the engine. it maintains the correct alignment and
supports the weight of the internal components.
Figure 81.
1
2
1 Bedplate
2 Crankcase

8. 15 - Engine
12 - Crankshaft
00 - General
15 - 35 9813/6200-1 15 - 35
00 - General
Introduction .................................................... 15-35
Technical Data ............................................... 15-36
Component Identification ............................... 15-36
Check (Condition) .......................................... 15-37
Remove and Install ....................................... 15-37
Introduction
The crankshaft is housed inside the crankcase.
It is connected to the piston via a connecting
rod, they form a simple mechanism that converts
reciprocating motion into rotating motion. Refer to
Engine- General, Operation, The Four Stroke Cycle
(PIL 15-00).

9. 15 - Engine
12 - Crankshaft
00 - General
15 - 36 9813/6200-1 15 - 36
Technical Data
Table 41.
DataDescription
Standard Service limit
Thrust washer
thickness
2.95–3mm 0.5mm
Crankshaft end
play
0.1–0.3mm 0.5mm
• Make sure that the oil grooves of all of the thrust
washers are toward the crankshaft.
Figure 82.
BA
D
C
A Crankshaft
B Main bearing holder bolt
C Thrust washer
D Top thrust washer
• If the crankshaft end play exceeds the service
limit, check the thrust washers for wear.
Figure 83.
A
E
F
A Crankshaft
E Allen head screw
F Retaining bolt
Table 42. Torque Values
Item Description Nm
B Main bearing holder bolt 52
E Allen head screw 27
F Retaining bolt 52
Component Identification
Figure 84.
B
A
A Crankcase
B Crankshaft

10. 15 - Engine
12 - Crankshaft
00 - General
15 - 37 9813/6200-1 15 - 37
Check (Condition)
1. Check the main bearing surfaces for damage and
excessive wear.
2. Measure the crankshaft diameters to confirm
they are within service limits. Refer to
Crankshaft- Technical Data (PIL 15-12).
3. Check that the oilway cross drillings in the
crankshaft are clear and free from debris.
Blocked or restricted oilways will cause oil
starvation at the big end bearings.
Remove and Install
CAUTION This component is heavy. It must only
be removed or handled using a suitable lifting
method and device.
Remove
1. Remove the engine oil relief valve. Refer to (PIL
15-60).
2. Remove the crankshaft rear seal. Refer to (PIL
15-12).
3. Remove the engine oil pump and the suction
pipe. Refer to (PIL 15-60).
4. Remove the pistons and the connecting rods.
Refer to (PIL 15-36).
5. Mount the engine in a suitable stand with the rear
end facing upwards.
6. Remove the bolts from the crankcase.
7. Remove the Allen screws from the crankcase.
8. Attach a suitable lifting device to the crankshaft
assembly.
9. Carefully lift the crankshaft assembly from the
crankcase.
10. If necessary, gently tap the nose of the crankshaft
with a soft faced hammer.
11. Install the nut for the crankshaft pulley to protect
the nose of the crankshaft. Do not scratch the
finished surfaces of the crankshaft.

11. 15 - Engine
12 - Crankshaft
00 - General
15 - 38 9813/6200-1 15 - 38
Figure 85.
C
D
A
B
A Crankshaft
B Crankcase
C Bolt
D Allen screw
Figure 86.
E
A
B
A Crankshaft
B Crankcase
E Lifting device
Install
1. Installation is the opposite of the removal
procedure. Additionally do the following steps.
2. Before installation make sure that all the
components are clean and free from damage.
3. Tighten the bolts and the screws to the correct
torque value.
4. Check the crankshaft end play.
4.1. Push the crankshaft towards the front of the
engine.
4.2. Install a DTI (Dial Test Indicator) to
the crankcase and the rear face of the
crankshaft.
4.3. Push the crankshaft toward the rear of the
engine.
4.4. Measure the crankshaft end play with the
DTI.
4.5. Make sure that the end play does
not exceed the maximum permissible
crankshaft end play. Refer to Crankshaft -
Technical Data - (PIL 15-12).
Table 43. Torque Values
Item Description Nm
C Bolt 52
D Allen screw 27

12. 15 - Engine
12 - Crankshaft
03 - Main Bearing
15 - 39 9813/6200-1 15 - 39
03 - Main Bearing
Introduction .................................................... 15-39
Check (Condition) .......................................... 15-40
Remove and Install ....................................... 15-41
Introduction
In a piston engine, the main bearings are the
bearings on which the crankshaft rotates.
The bearings hold the crankshaft in place and
prevent the forces created by the piston and
transmitted to the crankshaft by the connecting rods
from dislodging the crankshaft, instead forcing the
crank to convert the reciprocating movement into
rotation.
Figure 87.
A
B
A Main bearing
B Main bearing bolts

13. 15 - Engine
12 - Crankshaft
03 - Main Bearing
15 - 40 9813/6200-1 15 - 40
Check (Condition)
Check the condition of the main bearings by
measuring the clearance between the two bearing
halves.
If the crankshaft journals and the bores for the
crankcase and connecting rods were measured,
no further checks are necessary. If the bearing
clearance measurement is necessary, the use of
the plastic gauge is an acceptable method. The
plastic gauge is less accurate on journals with small
diameters if the clearances are less than 0.1mm.
When you use the plastic gauge make a note of the
following:
• Make sure that the backs of the bearings and
the bores are clean and dry.
• Make sure that the bearing locking tabs are
properly seated in the tab grooves.
• The crankshaft must be free of oil at the contact
points of the plastic gauge.
Table 44. Plastic Gauges
Colour code Dimensions
Green 0.025–0.076mm
Red 0.051–0.152mm
Blue 0.102–0.229mm
Yellow 0.23–0.51mm
Measurement Procedure
1. Put the plastic gauge on the crown of the bearing
that is in the cap.
2. Do not allow the plastic gauge to extend over the
edge of the bearing.
3. Use the correct torque-turn specifications in
order to install the bearing cap.
4. Do not use an impact wrench. Be careful not to
dislodge the bearing when the cap is installed.
5. Do not turn the crankshaft when the plastic gauge
is installed.
6. Carefully remove the cap, but do not remove the
plastic gauge.
Figure 88.
A
B
A Plastic gauge
B Bearing
7. Measure the width of plastic gauge while the
plastic gauge is in the bearing cap or on the
crankshaft journal.
8. Remove all of plastic gauges before you install
the bearing cap.

14. 15 - Engine
12 - Crankshaft
03 - Main Bearing
15 - 41 9813/6200-1 15 - 41
Remove and Install
Remove
1. Remove the crankshaft. Refer to (PIL 15-12).
2. Make sure that the bearing caps are marked for
orientation and the correct position.
3. Remove the bolt and the upper main bearing cap
from the lower main bearing cap.
4. Remove the thrust washer1 and the thrust
washer2.
5. Remove the upper main bearing and the lower
main bearing from the upper main bearing cap
and the lower main bearing cap respectively.
6. Keep the main bearings with the respective
bearing caps.
7. Do not remove the dowels from the main bearing
caps.
8. Remove the front bearing with the driver tool.
Figure 89.
B
B
G
H
F
A
A
D
F
E
G
C
A Bolt B Upper main bearing cap
C Thrust washer1 D Upper main bearing
E Lower main bearing F Lower main bearing cap
G Thrust washer2 H Dowel

15. 15 - Engine
12 - Crankshaft
03 - Main Bearing
15 - 42 9813/6200-1 15 - 42
Figure 90.
J K
L
M
J
N
J Front bearing
K Joint
L Chamfer
M Oil supply hole
N Driver tool
Install
1. Clean the crankshaft thoroughly. Check the
condition of the crankshaft. Refer to (PIL 15-12).
2. Clean all the bearings and thrust washers.
Inspect all the components for wear or damage.
3. Install the upper main bearing to the upper main
bearing cap.
4. Make sure that the locating tab for the upper main
bearing is seated in the slot in the upper main
bearing cap.
4.1. The upper bearing has a groove.
5. Install the lower main bearing to the lower main
bearing cap.
6. Make sure that the locating tab for the lower main
bearing is seated in the slot in the lower main
bearing cap.
6.1. The lower bearing is a plain bearing that has
oil holes.
7. Lubricate the main bearings with clean engine oil.
8. Keep the upper and the lower main bearing cap
in position on the crankshaft.
9. Make sure that the bearing caps are installed in
the correct location and orientation. The locating
tabs for the upper and the lower bearings should
be on the same side of the engine.
10. Make sure that the dowels are in the correct
position. This is to make sure that the two halves
of the main bearing caps are aligned.
11. Install the thrust washer1 and thrust washer2
12. Make sure that the thrust washers are aligned
correctly and the oil grooves are facing the
crankshaft.
13. Install the bolt and tighten to the correct torque
value.
14. Install the front bearing with the driver tool as
follows:
14.1.Make sure that the oil supply hole is aligned
with the oil gallery in the crankcase.
14.2.Make sure that the joint is facing upwards.
14.3.Make sure that the chamfer faces towards
the crankcase.
15. Install the crankshaft. Refer to (PIL 15-12).

16. 15 - Engine
12 - Crankshaft
06 - Front Oil Seal
15 - 43 9813/6200-1 15 - 43
06 - Front Oil Seal
Remove and Install
Special Tools
Description Part No. Qty.
Slide Hammer Kit 993/68100 1
Remove
1. Make the machine safe. Refer to (PIL 01-03).
2. Remove the crankshaft pulley. Refer to (PIL
15-12).
3. Do not damage the crankshaft during the
removal process of the crankshaft front oil seal.
4. Drill the front oil seal with a specified sized drill
bit.
Dimension: 4mm
Figure 91.
A
B
C
A Front case
B Front oil seal
C Slide hammer
4.1. Make sure that the main lip is used to
remove the front oil seal.
4.2. Do not damage the edge of the housing for
the front oil seal.
5. Remove the front oil seal with a slide hammer.
Special Tool: Slide Hammer Kit (Qty.: 1)
6. Alternate the position of the slide hammer puller
from one hole to another hole. This will allow you
to evenly remove the front oil seal from the front
case.
Alternative Removal Procedure
1. Remove the crankshaft pulley. Refer to (PIL
15-12).
2. Remove the timing gear front case. Refer to (PIL
15-51).
3. Press the front oil seal with a suitable mandrel
and remove it from the front case.
4. Support the front case to prevent damage to the
front case.
Install
1. Make sure that the bore in the front case and the
nose of the crankshaft are clean and free from
damage.
2. Lubricate the lip of the new crankshaft front seal
with clean engine oil.
3. Position the front oil seal in the bore of the front
case.
4. Make sure that the lip of the front oil seal that is
spring loaded is facing toward the inside of the
front case and that it is square with the bore of
the case for the front oil seal.
5. Install the front oil seal to the front case.
Figure 92.
A
B
D
A Front case
B Front oil seal
D Soft hammer
6. If necessary, hit the front oil seal with a soft
hammer.
7. If removed, install the timing gear front case.
Refer to (PIL 15-51).
8. Install the crankshaft pulley. Refer to (PIL 15-12).

17. 15 - Engine
12 - Crankshaft
09 - Rear Oil Seal
15 - 44 9813/6200-1 15 - 44
09 - Rear Oil Seal
Remove and Install
Consumables
Description Part No. Size
Clear Silicone Sealant 4102/0901 0.31L
Remove
1. Make the machine safe. Refer to (PIL 01-03).
2. Remove the flywheel. Refer to (PIL 15-54).
3. Remove the bolt.
4. Remove the flywheel housing and the back plate
from the crankcase. Refer to (PIL 15-54).
5. Remove and discard the rear oil seal.
Figure 93.
A
B
F
E
G
D
C
A Rear oil seal
B Back plate
C Bolt
D Dowel
E Crankcase
F Crankshaft flange
G Silicone Adhesive
Install
1. Make sure that the mating surface of the
crankcase, back plate and the flywheel housing
are clean and free from damage.
2. Inspect the dowels. If the dowels are damaged,
replace them.
3. Make sure that the crankshaft flange is clean
and free from damage. It is possible to reclaim
a crankshaft flange that has a worn seal surface
or a damaged seal surface by installing a wear
sleeve. Refer to (PIL 15-12).
4. Apply clean engine lubricating oil to the flange of
the crankshaft around the running surface of the
rear oil seal.
5. Align the new rear oil seal with the flange of the
crankshaft.
6. Carefully install the rear oil seal onto the
crankshaft flange.
7. Apply a continuous bead of Silicone Adhesive to
the rear face of the crankcase around the edge
of the rear oil seal and the plug.
Consumable: Clear Silicone Sealant
8. Align the flywheel housing and the back plate to
the dowels.
9. Install the flywheel housing and the back plate.
Refer to (PIL 15-54).
10. Install the bolt to the crankcase.
11. Tighten the bolt to the correct torque value.
12. Install the flywheel. Refer to (PIL 15-54).
Table 45. Torque Values
Item Description Nm
C Bolt 25

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19. 15 - Engine
12 - Crankshaft
12 - Pulley
15 - 45 9813/6200-1 15 - 45
12 - Pulley
Remove and Install
Remove
1. Make the machine safe. Refer to (PIL 01-03).
2. Remove the engine drive belt. Refer to (PIL
15-18).
3. Loosen the nut. Do not remove the nut at this
time.
4. Install the puller on the pulley with the bolt (x3).
Figure 94.
B
E
F
B Pulley
E Puller
F Bolt (x3)
5. Pull out the pulley from the crankshaft with the
puller.
6. Remove the bolt (x3) and the puller from the
pulley.
7. Remove the loosened nut.
8. Remove the pulley from the crankshaft.
9. Remove the woodruff key from the crankshaft.
Figure 95.
A
B
C
D
A Woodruff key
B Pulley
C Nut
D Crankshaft
Install
1. Make sure that all the components are clean and
free from damage.
2. Replace any components that are damaged.
3. Make sure that the taper of the crankshaft and
the bore of the crankshaft pulley are clean and
dry.
4. Install the woodruff key to the crankshaft.
5. Install the pulley to the crankshaft.
6. Lubricate the nut with clean engine oil and install
it.
7. Tighten the nut to the correct torque value.
8. Install the engine drive belt. Refer to (PIL 15-18).
Table 46. Torque Values
Item Description Nm
C Nut 304

20. 15 - Engine
12 - Crankshaft
24 - Wear Sleeve
15 - 46 9813/6200-1 15 - 46
24 - Wear Sleeve
Remove and Install
The wear sleeves are used to reclaim worn seal
surfaces or damaged seal surfaces. The wear
sleeves are not original equipment.
Remove
1. Make the machine safe. Refer to (PIL 01-03).
2. Remove the rear oil seal. Refer to (PIL 15-12).
3. Mark a deep score line across the crankshaft
wear sleeve with a sharp tool.
3.1. Take care not to damage the crankshaft.
Figure 96.
A
B
A Wear sleeve
B Crankshaft
4. Insert a thin blade between the wear sleeve
and the crankshaft below the scored line. The
crankshaft wear sleeve will separate along the
line.
5. Remove and discard the wear sleeve from the
crankshaft.
Install
1. Make sure that the crankshaft is thoroughly clean
and dry. Remove any areas of raised damage.
2. Apply a small continuous bead of liquid gasket
to the inner surface of the wear sleeve at the
specified position. Refer to Figure 97.
Figure 97.
AC
C
A Wear sleeve
C Liquid gasket
3. Apply a bead of liquid gasket at the specified
distance from the flange end of the crankshaft
wear sleeve.
Distance: 5mm
4. Align the wear sleeve with the crankshaft.
5. Position the installation tool that is provided with
the wear sleeve over the crankshaft.
6. Drive the wear sleeve on the crankshaft with a
slide hammer.
7. Make sure that the distance from the edge of the
wear sleeve to the rear face of the crankshaft is
the same as specified. Refer to Figure 98.
Distance: 2.5 ± 0.1mm
Figure 98.
A
B
DE
A Wear sleeve
B Crankshaft
D Installation tool
E Distance from the edge of the wear sleeve to
the rear face of the crankshaft (2.5 ± 0.1mm)
8. Remove the installation tool.
9. Make sure that the wear sleeve has no rough
edges.
10. Install the new rear oil seal. Refer to (PIL 15-12).