This service manual provides instructions for servicing an excavator engine. It contains sections on general information, components, operation, maintenance, removal and installation procedures for the rocker and fittings assembly. The summary focuses on the rocker and fittings section, which describes the components of the rocker assembly such as the rocker arms, shaft and springs. It provides details on how the assembly works, lubrication paths, and maintenance checks. Procedures for removing, installing, disassembling and assembling the rocker assembly are included.

1. SERVICE MANUAL
EXCAVATOR
67C-1
EN - 9813/3450 - ISSUE 2 - 04/2018
This manual contains original instructions, verified by
the manufacturer (or their authorized representative).
Copyright 2018 © 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, Couplings and Load
Handling
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
42 - Rocker and Fittings
00 - General
15 - 145 9813/3450-2 15 - 145
00 - General
Introduction .................................................. 15-145
Component Identification ............................. 15-146
Operation ..................................................... 15-147
Check (Condition) ........................................ 15-148
Remove and Install ..................................... 15-148
Disassemble and Assemble ........................ 15-151
Introduction
The rocker assembly is an indirect valve actuating
system consisting of rocker arms and a shaft.
The rocker arm is an oscillating lever that conveys
radial movement from the cam lobe into linear
movement at the poppet valve to open it. One end is
raised and lowered by a rotating lobe of the camshaft
via a tappet and push rod while the other end acts
on the bridge piece which is connected to the valve
stem.

3. 15 - Engine
42 - Rocker and Fittings
00 - General
15 - 146 9813/3450-2 15 - 146
Component Identification
Figure 233.
B
E
D
A
C
A Rocker arm shaft B Rocker arm distancing spring
C Rocker arm shaft support D Exhaust rocker arm
E Intake rocker arm
Figure 234.
F
J
G
K
HL
F Rocker arm body G Hydraulic tappet oil refill line
H Valve tappet lubrication line J Valve tappet
K Hydraulic tappet L Oil flow line

4. 15 - Engine
42 - Rocker and Fittings
00 - General
15 - 147 9813/3450-2 15 - 147
Operation
When the camshaft lobe raises the push-rod, the
push-rod pushes the rocker arm up. Due to this the
rocker arm presses down on the valve stem to open
the valve. When the rocker arm returns due to the
camshafts rotation, the valve spring closes the valve.
Lubrication
Oil is fed from the main gallery through a drilling
which passes up through the crankcase and cylinder
head to a small transfer gallery under the rocker
shaft pedestal. The oversize rocker shaft fixing bolt
hole allows oil to pass into a drilling in the centre of
the rocker shaft. Further cross drillings transfer oil
to each of the rocker pivot bushes. A cross drilling
in each rocker transfers oil to the top of the rocker
where it flows by gravity along a groove to the rocker
tip.
Figure 235.
1 Main gallery 2 Small transfer gallery
3 Shaft pedestal 4 Rocker shaft fixing bolt hole
5 Centre rocker shaft drilling 6 Cross drillings
7 Rocker pivot bushes 8 Cross drilling
9 Groove

5. 15 - Engine
42 - Rocker and Fittings
00 - General
15 - 148 9813/3450-2 15 - 148
Check (Condition)
1. Check the rocker shaft and rocker bushings for
signs of damage and excessive wear. Measure
the rocker shaft diameter and rocker bearing
bushes to confirm they are within service limits.
Refer to Technical Data. Note: The rocker
bearing bushes are not renewable. If a rocker
bearing bush is damaged or worn the rocker
must be renewed as a complete assembly.
Refer to: PIL 15-42.
2. Make sure that all oil-ways and cross drillings in
the rocker shaft, rocker arms and pedestals are
clear and free from debris. Use an air line to blow
through cross drillings.
Remove and Install
Before Removal
1. 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.
2. Get access to the engine.
3. Disconnect and remove the fuel pipes from the
fuel injectors. Refer to (PIL 18-96).
4. Remove the rocker cover. Refer to (PIL
15-42-06).
Remove
1. Remove the rocker shaft fixing screws.
Figure 236.
BA
C
A Rocker shaft fixing screw (x3)
B Rocker arm assembly
C Cylinder head
2. Make sure that you keep all the fixing screws in
their original positions.
3. Lift the rocker arm assembly from the cylinder
head completely.

6. 15 - Engine
42 - Rocker and Fittings
00 - General
15 - 149 9813/3450-2 15 - 149
Figure 237.
B
C
B Rocker arm assembly
C Cylinder head
4. Lift off the valve bridge pieces from the pairs of
inlet and exhaust valves.
Figure 238.
D
E
D Valve bridge (x6)
E Push rod (x6)
5. Remove the push rods from the crankcase.
Before Installation
1. Make sure that all items are clean and free from
damage and corrosion. If components within the
rocker assembly are damaged or worn.
2. Make sure that all oilways and cross drillings in
the cylinder head, rocker shaft and pedestals are
clear and free from debris. Use an air line to blow
through the cross drillings.
3. Use a suitable degreasing agent to clean the top
of the cylinder head.
Install
1. Replacement is the reversal of the removal
procedure.
2. Insert the push rods into the crankcase. Make
sure that they engage with the camshaft tappets.
Figure 239.
E
E
F
E Push rod
F Camshaft tappet
3. Install the bridge pieces on to the pairs of inlet
and exhaust valves in the cylinder head.
Figure 240.
D
D
C
C Cylinder head
D Valve bridge
4. Align the rocker arm assembly on a level surface.

7. 15 - Engine
42 - Rocker and Fittings
00 - General
15 - 150 9813/3450-2 15 - 150
5. Make sure you install the rocker arm assembly
on the cylinder head with respect to the plug and
the holder.
Figure 241.
E
H
E Push rod
H Plug
Figure 242.
G
B
B Rocker arm assembly
G Holder
6. Make sure that the rocker arm assembly is
seated properly on the push rod.
7. Make sure that you put the crankshaft gear key
in the position as shown to avoid the rocker arm
rod bending at the time of tightening the fixing
screws.
Figure 243.
J
J Gear key
8. Put the rocker arm fixing screws and tighten the
screws in the sequence shown.
Figure 244.
A
B
2
31
A Rocker shaft fixing screw (1-3)
B Rocker arm assembly
9. Tighten the screws to the correct torque value.
After Installation
1. Measure and adjust the valve clearances. Refer
to (PIL 15-30).
2. Install the rocker cover. Refer to (PIL 15-42-06).
3. Install and connect the fuel pipes to the fuel
injectors. Refer to (PIL 18-96).
Table 71. Torque Values
Item Nm
A 25

8. 15 - Engine
42 - Rocker and Fittings
00 - General
15 - 151 9813/3450-2 15 - 151
Disassemble and Assemble
Special Tools
Description Part No. Qty.
Insertion Pliers for
Hydraulic Tappets
892/12425 1
Before Disassembly
1. Remove the rocker cover.
Refer to: PIL 15-42-06.
2. Remove the rocker assembly.
Refer to: PIL 15-42-00.
Disassemble
1. Remove the retainer ring.
Figure 245.
C
D
B
A
A Discharge rocker arm
B Hydraulic tappet
C Retainer
D Shoulder ring
2. Remove the shoulder ring.
3. Remove the rockers and the holders from the
rocker shaft.
Figure 246.
A
G
E
F
A Discharge rocker arm
E Rocker shaft
F Holder
G Holder 1
4. Label the rockers and the holders to make sure
that they are installed in the correct positions on
assembly.
5. Remove the tappets from the rocker.
Figure 247.
B A
A Discharge rocker arm
B Hydraulic tappet
6. Check (Condition) of the rocker arm assembly for
signs of damage and excessive wear.
Refer to: PIL 15-42-00.
Assemble
1. The assembly procedure is the opposite of
the disassembly procedure. Additionally do the
following steps.
2. Install the tappets into the rocker arm.
2.1. Insert the tappets into the hydraulic tappet
insertion pliers.
Special Tool: Insertion Pliers for Hydraulic
Tappets (Qty.: 1)
2.2. Fill the chamber of the tappet with oil.
2.3. Put the pad on the tappet.

9. 15 - Engine
42 - Rocker and Fittings
00 - General
15 - 152 9813/3450-2 15 - 152
Figure 248.
A
B
H
J
A Discharge rocker arm
B Hydraulic tappet
H Chamber
J Pad
2.4. Position the rocker arm in the pliers.
2.5. Use the pliers to push the tappet through
the rocker arm until the tappet is properly
inserted.
3. Lubricate the rocker shaft with clean engine oil.
4. Install the rocker arms in the correct position, turn
the rocker shaft with the lower height towards the
timing gear system side.
5. Put the lock ring into the seat of the rocker shaft.
Figure 249.
D
C
C
E
L
K
E
C Retainer
D Shoulder ring
E Rocker shaft
K Seat
L Rocker shaft lower height
6. Position the fixing screw support surface facing
upwards.
7. Put the two shoulder rings on the rocker shaft.
8. Sequentially put the suction rocker arm, the
holder and the discharge rocker arm on the
rocker shaft.
Figure 250.
F
D
C A
N
G
M
E
A Discharge rocker arm
C Retainer
D Shoulder ring
E Rocker shaft
F Holder
G Holder 1
M Spring
N Suction rocker arm
9. The discharge rocker arm is shorter than the
suction rocker arm.
10. Install the spring on the rocker shaft.
11. Do the steps 8 and 10 for all the remaining rocker
arms.
12. Install the holder 1 with the last pair of rocker arm
towards the flywheel.
13. The spring makes sure that the holder and the
holder 1 are kept in place.
14. Make sure that the rockers are installed in their
original positions along the rocker shaft.
15. Put the shoulder rings and the lock ring to lock all
the components on the rocker shaft.
After Assembly
1. Install the rocker assembly.
Refer to: PIL 15-42-00.
2. Install the rocker cover.
Refer to: PIL 15-42-06.

10. 15 - Engine
42 - Rocker and Fittings
01 - Rocker Arm
15 - 153 9813/3450-2 15 - 153
01 - Rocker Arm
Remove and Install
Refer to Rocker Assembly-Remove and Install. Refer
to: PIL 15-42-00.

11. 15 - Engine
42 - Rocker and Fittings
03 - Rocker Shaft
15 - 154 9813/3450-2 15 - 154
03 - Rocker Shaft
Remove and Install
Refer to Rocker Assembly- Disassemble-Assemble.
Refer to (PIL 15-42-00).

12. 15 - Engine
42 - Rocker and Fittings
06 - Rocker Cover
15 - 155 9813/3450-2 15 - 155
06 - Rocker Cover
Introduction .................................................. 15-155
Remove and Install ..................................... 15-156
Introduction
The rocker arm cover is installed over the rocker and
fittings. It carries the engine oil for the lubrication of
the rocker components.

13. 15 - Engine
42 - Rocker and Fittings
06 - Rocker Cover
15 - 156 9813/3450-2 15 - 156
Remove and Install
Before Removal
1. 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.
2. Clean the engine.
Refer to: PIL 15-00-00.
Remove
1. Get access to the engine.
2. Remove the high pressure fuel pipes.
Refer to: PIL 18-96-03.
3. Remove the fuel bleed off fuel pipes.
Refer to: PIL 18-96-06.
4. Disconnect the electrical connectors at the fuel
injectors.
Refer to: PIL 18-18-03.
5. Disconnect the electrical connector at the coolant
temperature sensor.
Refer to: PIL 15-84-33.
6. Move the electrical harness away from the rocker
cover.
7. Progressively remove the rocker arm cover
screws from 1 to 6 in reverse order, starting at
bolt 6.
Figure 251.
8. Lift the rocker cover from the cylinder head.
Figure 252.
A
B
C
A Rocker arm cover
B Screws
C Gasket
9. Discard the gasket.
10. The rocker cover injector seals must be replaced.
Refer to: PIL 18-18-03.
Install
1. Remove all oil and sludge contamination from
inside the valve chamber.
2. Use a new rocker arm cover gasket.
3. Make sure you align the gasket on the cylinder
head with the rocker cover fastening screws.
4. Locate the two guide pins before mounting the
rocker arm cover.
5. Put sleeves/covers on the four injectors to
prevent from damage.
6. Apply a Vaseline lubricant to the seals.
Figure 253.
D
C
D
E
A
F
B
A Rocker arm cover
B Screws
C Gasket
D Guide pins
E Seal (lubricate upper part)
F Seal (lubricate inner part)

14. 15 - Engine
42 - Rocker and Fittings
06 - Rocker Cover
15 - 157 9813/3450-2 15 - 157
7. Install the rocker arm cover and put the screws
in sequence from 1 to 6.
8. Tighten the screws to the correct torque value.
9. Remove the sleeves/covers.
After Installation
1. The high pressure fuel pipes must be replaced
with new parts.
Refer to: PIL 18-96-03.
2. Start the engine and check for oil and fuel leaks.
Table 72. Torque Values
Item Nm
B 10

15. 15 - Engine
42 - Rocker and Fittings
09 - Push Rod
15 - 158 9813/3450-2 15 - 158
09 - Push Rod
Introduction .................................................. 15-158
Remove and Install ..................................... 15-159
Introduction
Push rods are used in a reciprocating engine to open
and close the valves. They are moved by the cams
on the camshaft. One end is pushed up by the cam
and the other end makes contact with the rocker
arms which rotates and pushes the valve open.

16. 15 - Engine
42 - Rocker and Fittings
09 - Push Rod
15 - 159 9813/3450-2 15 - 159
Remove and Install
Refer to Rocker Assembly- Remove and Install.
Refer to (PIL 15-42-00).

17. 15 - Engine
42 - Rocker and Fittings
21 - Tappet
15 - 160 9813/3450-2 15 - 160
21 - Tappet
Introduction .................................................. 15-160
Technical Data ............................................. 15-161
Component Identification ............................. 15-162
Operation ..................................................... 15-163
Check (Condition) ........................................ 15-164
Calibrate ...................................................... 15-164
Remove and Install ..................................... 15-165
Introduction
Hydraulic Tappet
A hydraulic tappet is a device for maintaining zero
valve clearance in an internal combustion engine.
The zero tolerance allows the valve train to operate
with zero clearance leading to quieter operation,
longer engine life, and eliminating the need for
periodic adjustment of valve clearance.

18. 15 - Engine
42 - Rocker and Fittings
21 - Tappet
15 - 161 9813/3450-2 15 - 161
Technical Data
Tappets Dimensions
Figure 254.
A
C
B
Table 73.
Item Dimension Aspect Dimension
A Perpendicularity 0.02mm (max)
B Length 46.5 ± 0.2mm
Clearance between Tappet and Housing
Figure 255.
D
E
F
E Tappet
F Tappet housing
Table 74.
Item Dimensions Clearance Wear Limit
C 11.966-11.984mm
D
(1)
12.000-12.018mm
0.060-0.105mm 0.080mm
(1) Measure the diameter at two points. The difference between the two values measured must not be more
than be 0.02mm.

19. 15 - Engine
42 - Rocker and Fittings
21 - Tappet
15 - 162 9813/3450-2 15 - 162
Component Identification
Figure 256.
C
A
D
E
F
H
G
B
A Low pressure chamber B High pressure chamber
C Hydraulic tappets oil refill pipe D Retaining ring
E Piston F Unidirectional valve
G Tappet body H Spring

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21. 15 - Engine
42 - Rocker and Fittings
21 - Tappet
15 - 163 9813/3450-2 15 - 163
Operation
Hydraulic Tappet
The operating principle of the hydraulic tappet is
based on the incompressibility of the liquid and on
controlled leakage between the piston and the tappet
body.
A constant supply of pressurised oil is provided to the
low pressure chamber. The pressurized oil can only
get the access to the high pressure chamber through
the unidirectional (non-return) valve.
The high pressure chamber is filled when the rocker
arm is on the base radius of the cam and the spring
holds the piston against the valve stem preventing
from system play as well as vibration and noise.
Due to the spring movement, the tappet extends.
This creates a small pressure decrease in the high
pressure chamber to open the non-return valve. Oil
is then transferred from the low pressure chamber
to the high pressure chamber to restore the proper
amount of oil required to eliminate any play in the
valves.
Difficult Operating Conditions
For proper operation of the hydraulic tappets it is
essential that the low pressure chamber of the piston
is always full of oil.
In some conditions this may not occur (due to the
fact that oil leaks away when the engine is switched
off, which can also partially drain the tappets): this
situation will result in play that will occur with a typical
noise similar to ticking, not to be confused with the
normal ticking of the injectors.
When the engine is cold, the tappet filling time could
be very long if the oil used is not suitable for the
specific environmental conditions.
If the engine is very hot or at idle speed, oil pressure
may be low, and small air bubbles could form in
the circuit. Because of this, the lubricant becomes
compressible, thus compressing the tappet slightly
and producing valve play which is responsible for the
ticking sound.
In all cases, the ticking should not last too long (max
5 minutes) if not, the problem will surely be due to
the poor quality of the oil, wear or impurities that,
transported by the oil, can infiltrate between the ball
valve and its seat inside the piston This affects the
operation of the tappet itself. In these cases you must
replace the oil or the hydraulic tappets.
Continuous ticking or abnormal sound for prolonged
periods is a symptom of a possible malfunction, and
requires the removal and replacement of oil and
hydraulic tappets.

22. 15 - Engine
42 - Rocker and Fittings
21 - Tappet
15 - 164 9813/3450-2 15 - 164
Check (Condition)
Tappets and Tappet Housing Check
1. Put the tappet on a V-notch surface plate.
2. Measure the following dimensions of the tappet
and tappet housing.
2.1. Perpendicularity of the base with a dial
gauge.
2.2. Length of the tappet to assess the wear.
2.3. Diameter of the tappet housing with an
internal dial gauge.
3. Make sure that you measure the housing
diameter at two locations and the difference
between the two values should not be more than
0.02mm.
4. Measure the clearance between the tappet and
the tappet housing from the values derived in
step 2.
5. Make sure that all the values are within the
allowable limits.
Refer to: PIL 15-42-21.
Calibrate
Tappets Dimensions
Use a surface plate and a dial gauge as shown.
Check the perpendicularity of the plate, making the
tappet rotate in the direction of the arrow. With a
gauge, check the length of the tappet to assess wear.
The values measured must be within tolerances.
Refer to: PIL 15-42-21.
Figure 257.
A
C
B
A Tappet diameter
B Tappet length
C Perpendicularity
Clearance between Tappet and Housing
Use an internal dial gauge to measure the diameter
of the tappet housings. Measure quota in two
different points. The difference between the two
values measured must be within tolerance. Refer to:
PIL 15-42-21.
Figure 258.
D
E
F
D Quota
E Tappet
F Tappet housing

23. 15 - Engine
42 - Rocker and Fittings
21 - Tappet
15 - 165 9813/3450-2 15 - 165
Remove and Install
The tappets can be taken out when the engine is
inverted and when the camshaft is removed. Refer
to Camshaft- Remove and Install.