PDF Service Manual Bobcat 331 331E 334 - 5 MB
Unlock the full potential of your compact excavator with the official service manual for the Bobcat 331, 331E, and 334 models.
This comprehensive guide provides step-by-step instructions for any repair or maintenance procedure you might encounter.
From engine diagnostics to hydraulic system troubleshooting, this manual is the ultimate resource for both professional technicians and owners.
Ensure your Bobcat excavator performs at its best for years to come.
It contains the same information used by certified Bobcat mechanics.
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--- Page 1 ---
331
331E
334 Service
Manual
331 - S/N 234313000 & Above
331E - S/N 234412000 & Above
334 - S/N 234513000 & Above
(G Series)
6903830 (10-09) Printed in U.S.A. ©Bobcat Company 2009
--- Page 3 ---
SAFETY INSTRUCTIONS The following publications provide information on the
safe use and maintenance of the Bobcat machine and
attachments:
Safety Alert Symbol
• The Delivery Report is used to assure that complete
This symbol with a warning statement means: instructions have been given to the new owner and
“Warning, be alert! Your safety is involved!” that the machine is in safe operating condition.
Carefully read the message that follows.
• The Operation & Maintenance Manual delivered with
the machine or attachment contains operating
information as well as routine maintenance and
service procedures. It is a part of the machine and can
WARNING be stored in a container provided on the machine.
Replacement Operation & Maintenance Manuals can
be ordered from your Bobcat dealer.
Instructions are necessary before operating or
servicing machine. Read and understand the • Machine signs (decals) instruct on the safe operation
Operation & Maintenance Manual, Operator’s and care of your Bobcat machine or attachment. The
Handbook and signs (decals) on machine. Follow signs and their locations are shown in the Operation
warnings and instructions in the manuals when & Maintenance Manual. Replacement signs are
making repairs, adjustments or servicing. Check for available from your Bobcat dealer.
correct function after adjustments, repairs or service.
Untrained operators and failure to follow instructions • An Operator’s Handbook fastened to the operator
can cause injury or death. cab. It’s brief instructions are convenient to the
W-2003-0903
operator. The handbook is available from your dealer
in an English edition or one of many other languages.
See your Bobcat dealer for more information on
translated versions.
IMPORTANT
• The AEM Safety Manual delivered with the machine
This notice identifies procedures which must be gives general safety information.
followed to avoid damage to the machine.
I-2019-0284 • The Service Manual and Parts Manual are available
from your dealer for use by mechanics to do shop-
type service and repair work.
• The Compact Excavator Operator Training Course is
DANGER available through your local dealer or at
www.training.bobcat.com or www.bobcat.com.
This course is intended to provide rules and practices
The signal word DANGER on the machine and in the of correct operation of the Bobcat excavator. The
manuals indicates a hazardous situation which, if not course is available in English and Spanish versions.
avoided, will result in death or serious injury.
D-1002-1107 • Service Safety Training Courses are available from
your Bobcat dealer or at www.training.bobcat.com
or www.bobcat.com. They provide information for
safe and correct service procedures.
WARNING • The Bobcat compact excavator Safety Video is
available from your Bobcat dealer or at
The signal word WARNING on the machine and in the www.training.bobcat.com or www.bobcat.com.
manuals indicates a potentially hazardous situation
which, if not avoided, could result in death or serious
injury.
W-2044-1107
SI EXC-0308 SM
331/331E/334 Excavator
V Service Manual
--- Page 4 ---
LIFTING AND BLOCKING THE EXCAVATOR Figure 10-10-1
Procedure
Always park the machine on a level surface.
WARNING
AVOID INJURY OR DEATH
Instructions are necessary before operating or
servicing machine. Read and understand the
Operation & Maintenance Manual, Operator’s
Handbook and signs (decals) on machine. Follow 1
P-49234
warnings and instructions in the manuals when
making repairs, adjustments or servicing. Check for
correct function after adjustments, repairs or service. Raise one side of the machine (approximately four
Untrained operators and failure to follow instructions inches) using the boom and arm [Figure 10-10-1].
can cause injury or death.
W-2003-0807
Raise the blade fully and install jack stands under the
blade and track frame (Item 1) [Figure 10-10-1]. Raise
the boom until all machine weight is on the jack stands.
Repeat the procedure for the other side.
WARNING Stop the engine.
Put jackstands under the front axles and rear corners
of the frame before running the engine for service.
Failure to use jackstands can allow the machine to
fall or move and cause injury or death.
W-2017-0286
331/331E/334 Excavator
10-10-1 Service Manual
--- Page 5 ---
OPERATOR CAB (ROPS/TOPS) (CONT’D) Opening the right front window
Right Side Windows Figure 10-20-14
Opening the right rear window
Figure 10-20-12
1
1
P-49119
Pull back on the latch (Item 1) [Figure 10-20-14].
P-49176
Figure 10-20-15
Pull out on the latch (Item 1) [Figure 10-20-12].
Figure 10-20-13
1
1 P-49120
Pull the latch/handle (Item 1) [Figure 10-20-15] back to
P-49177 open the window.
Push the handle forward to close the window.
Pull the latch/handle (Item 1) [Figure 10-20-13] forward
to open the window.
Push the handle back to close the window.
331/331E/334 Excavator
10-20-5 Service Manual
--- Page 6 ---
AIR CLEANER SERVICE Replacing The Filters
See the SERVICE SCHEDULE for the correct service Outer Filter
interval. (See SERVICE SCHEDULE on Page 10-50-1.)
Release the two fasteners (Item 2) [Figure 10-60-1].
Daily Check
Remove and clean the dust cup (Item 3) [Figure 10-60-
Figure 10-60-1 1].
1 Figure 10-60-2
2
1
3 2
P-49245
P-49246
Check the condition indicator (Item 1) [Figure 10-60-1]. If
the red ring shows in the condition indicator, the filter
needs to be replaced. Pull the outer filter (Item 1) [Figure 10-60-2] from the air
cleaner housing.
Replace the inner filter every third time the outer filter is
replaced or as indicated. Check the housing for damage.
Clean the housing and the seal surface. DO NOT use
compressed air.
Install a new filter.
331/331E/334 Excavator
10-60-1 Service Manual
--- Page 7 ---
FUEL SYSTEM (CONT’D) Removing Air From The Fuel System
Fuel Filter After replacing the fuel filter or when the fuel tank has run
out of fuel, air must be removed from the fuel system
See the SERVICE SCHEDULE for the service interval before starting the engine.
when to replace the fuel filter. (See SERVICE
SCHEDULE on Page 10-50-1.) Figure 10-80-5
Figure 10-80-4
3
1
1
2 P-49251
P-49249
Open the fuel filter vent (Item 1) and operate the hand
pump (priming bulb) (Item 2) [Figure 10-80-5] until the
Remove the filter (Item 1) [Figure 10-80-4]. fuel flows from the vent with no air bubbles.
Clean the area around the filter housing. Close the vent (Item 1) [Figure 10-80-5].
Put oil on the seal of the new filter. Start the engine. It may be necessary to open the vent
(Item 3) [Figure 10-80-5] (at the fuel injection pump)
Install the fuel filter, and hand tighten. briefly until the engine runs smoothly.
WARNING
AVOID INJURY OR DEATH
Diesel fuel or hydraulic fluid under pressure can
penetrate skin or eyes, causing serious injury or
death. Fluid leaks under pressure may not be visible.
Use a piece of cardboard or wood to find leaks. Do
not use your bare hand. Wear safety goggles. If fluid
enters skin or eyes, get immediate medical attention
from a physician familiar with this injury.
W-2072-0807
331/331E/334 Excavator
10-80-3 Service Manual
--- Page 8 ---
LUBRICATION OF THE HYDRAULIC EXCAVATOR
(CONT’D)
Procedure (Cont’d)
Figure 10-110-8
22
22
P-49271
22. Tailgate Hinge (2) [Figure 10-110-8].
331/331E/334 Excavator
10-110-3 Service Manual
--- Page 9 ---
HYDRAULIC SYSTEM
ARM CYLINDER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21-1
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21-8
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21-6 HYDRAULIC
Parts Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21-5 SYSTEM
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21-3
Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21-1
BLADE CYLINDER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-24-1
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-24-7
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-24-5
Parts Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-24-4
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . . 20-24-3
Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-24-1
BOOM CYLINDER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-20-1
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-20-10
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-20-8
Parts Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-20-7
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . . 20-20-4
Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-20-1
BOOM SWING CYLINDER . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22-1
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22-8
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22-6
Parts Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22-5
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22-3
Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-22-1
BOOM SWING LOCK VALVE . . . . . . . . . . . . . . . . . . . . . . . . 20-170-1
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-170-6
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-170-3
Parts Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-170-2
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . 20-170-1
BUCKET CYLINDER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-23-1
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-23-11
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-23-9
Parts Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-23-8
Removal And Installation (Extendible Arm) . . . . . . . . . . . . 20-23-5
Removal And Installation (Standard And Long Arm) . . . . . 20-23-3
Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-23-1
CASE DRAIN FILTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-160-1
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . 20-160-1
Continued On Next Page
331/331E/334 Excavator
20-01 Service Manual
--- Page 10 ---
HYDRAULIC SYSTEM INFORMATION
Glossary Of Hydraulic/Hydrostatic Symbols For Excavators
MS-1892-1
MC 2340 (6-2-98)
331/331E/334 Excavator
20-10-1 Service Manual
--- Page 11 ---
BOOM CYLINDER (CONT’D)
Testing (Cont’d)
Figure 20-20-9
2
1
P-22223
Remove the hose from the base end of the cylinder. Cap
the hose (Item 1) [Figure 20-20-9].
Start the engine and retract the boom cylinder.
If there is any oil leakage from the base end fitting (Item
2) [Figure 20-20-9], remove the cylinder for repair or
replacement.
331/331E/334 Excavator
20-20-3 Service Manual
--- Page 12 ---
ARM CYLINDER Figure 20-21-3
Testing
Lower the boom/bucket and blade to the ground.
1
With the engine off, turn the key to the ON position and
move both hydraulic control levers to relieve hydraulic
pressure. 2
Figure 20-21-1
P-53173
Remove the snap ring (Item 1) [Figure 20-21-3] and
washer.
Remove the rod end pin (Item 2) [Figure 20-21-3].
Figure 20-21-4
P-53163
Support the boom with a chain hoist [Figure 20-21-1].
Figure 20-21-2
1
P-53174
Start the engine and fully retract the cylinder rod (Item 1)
[Figure 20-21-4].
P-53172
Support the arm cylinder [Figure 20-21-2].
331/331E/334 Excavator
20-21-1 Service Manual
--- Page 13 ---
BOOM SWING CYLINDER Remove the floormat and floor panel. (See Removal And
Installation (Cab Equipped Excavators) on Page 40-110-
Testing 2.)
Lower the boom/bucket and blade to the ground. Remove the seat and seat mount. (See Removal And
Installation on Page 40-40-1.)
Figure 20-22-1
Figure 20-22-3
1
1
1
1
P-61111
P-61112
Place a block (Item 1) [Figure 20-22-1] under the rod
end of the boom swing cylinder. Remove the bolts (Item 1) [Figure 20-22-3] from the left
side of the rear floor plate.
Figure 20-22-2
2 Figure 20-22-4
1
1
1
P-55107
P-61113
Remove the snap ring and washer (Item 1) [Figure 20-
22-2] from the rod end pin of the cylinder. Remove the bolts (Item 1) [Figure 20-22-4] from the right
side of the rear floor panel.
Remove the pin (Item 2) [Figure 20-22-2].
Start the engine and fully retract the cylinder rod.
Stop the engine.
331/331E/334 Excavator
20-22-1 Service Manual
--- Page 14 ---
BUCKET CYLINDER Figure 20-23-3
Testing
1
Lower the boom/bucket and blade to the ground.
With the engine off, turn the key to the ON position and
move both hydraulic control levers to relieve hydraulic
pressure.
Figure 20-23-1
P-53182
Remove the link (Item 1) [Figure 20-23-3].
Figure 20-23-4
P-53163
Support the boom using a chain hoist [Figure 20-23-1].
Figure 20-23-2 1
2
1 P-53183
1
Start the engine and fully retract the cylinder rod (Item 1)
[Figure 20-23-4].
P-53181
Remove the snap rings (Item 1), washers and plate (Item
2) [Figure 20-23-2].
331/331E/334 Excavator
20-23-1 Service Manual
--- Page 15 ---
BUCKET CYLINDER (CONT’D) Figure 20-23-29
Assembly 3
Clean all parts in solvent and dry with compressed air.
Inspect all parts for wear or damage. Replace any worn 1
or damaged parts. 2
Always install new seals and O-rings. Lubricate all seals
and O-rings with clean hydraulic fluid before installation.
Use the following tools to assemble the cylinder:
MEL1396 - Universal Seal Expander
MEL1033 - Rod Seal Installation Tool N-22414
Piston Ring Compressor
MEL1075 - Adjustable Gland Nut Wrench
MEL1075-2 - Special Offset Pins Install the O-ring (Item 1) and seal (Item 2) on the piston
(Item 3) [Figure 20-23-29].
Figure 20-23-28
Figure 20-23-30
P-7424
N-22358
Install the seal on the tool and slowly stretch it until it fits
the piston [Figure 20-23-28]. Use a ring compressor to compress the seal to the
correct size. Leave the piston in the compressor for about
Allow the seal to stretch for 30 seconds before installing it three minutes [Figure 20-23-30].
on the piston.
331/331E/334 Excavator
20-23-11 Service Manual
--- Page 16 ---
BLADE CYLINDER (CONT’D) Figure 20-24-18
Assembly 3
Clean all parts in solvent and dry with compressed air.
Inspect all parts for wear or damage. Replace any worn 1
or damaged parts. 2
Always install new seals and O-rings. Lubricate all seals
and O-rings with clean hydraulic fluid before installation.
Use the following tools to assemble the cylinder:
MEL1396 - Universal Seal Expander
MEL1033 - Rod Seal Installation Tool N-22414
Piston Ring Compressor
MEL1075 - Adjustable Gland Nut Wrench
MEL1075-1 - Standard Pins Install the O-ring (Item 1) and seal (Item 2) on the piston
(Item 3) [Figure 20-24-18].
Figure 20-24-17
Figure 20-24-19
P-7424
N-22358
Install the new seal on the tool and slowly stretch it until it
fits the piston [Figure 20-24-17]. Use a ring compressor to compress the seal to the
correct size. Leave the piston in the compressor for about
Allow the seal to stretch for 30 seconds before installing it three minutes [Figure 20-24-19].
on the piston.
331/ 331E/334 Excavator
20-24-7 Service Manual
--- Page 17 ---
CLAMP CYLINDER (CONT'D)
Parts Identification
1. Grease fitting
2. Plug
3. O-Ring
4. Housing
5. Nut
6. Seal
7. Piston 1
8. Backup ring
9. Seal
10. Head
11. Wiper Seal 4
12. Rod
3
2
5
6
3
3
2 7
3
8
9
3
10
11
12
1
PE2447S
20-26-3 331/331E/334 Service Manual
--- Page 18 ---
MAIN RELIEF VALVE (Item 3) [Figure 20-30-1] is used to check the pressure
reducing valve.
Testing And Adjusting The Main Relief Valve
The following tools will be needed for the testing at the
All testing is done with the hydraulic oil at operating diagnostic coupler:
temperature and the at high idle speed. (See Engine on
Page SPEC-10-6.). MEL1355 - Test Kit includes the following:
MEL1355-3 - 5000 PSI Gauge
Figure 20-30-1 MEL1355-12 - Coupler
MEL1355-9 - Thermometer
System Pressures At Gauge Port Specifications
TEST CONDITIONS
3
1. Engine High Idle Speed
2. Warm oil over relief function to minimum 150° F (66°
1
C). Cycle all functions during warm up procedure.
Warm oil until the pressure build-up valve stabilizes
near its target pressure.
2 3. Activate function until cylinder movement stops. Hold
P-58833 over relief for 5-10 seconds.
Record pressure.
There is one diagnostic coupler (Item 1) that is used to
check the main relief. The second coupler (Item 2) is
used in assembly of the excavator. The third coupler
FUNCTION CIRCUIT TEST TARGET ACCEPTABLE
SYSTEM CHECK TO ENGAGE PRESSURIZED PORT (PSI) RANGE (PSI)
JOYSTICK PILOT PRESSURE ANY JOYSTICK FUNCTION JOYSTICK PILOT G 428 406 - 450
SYSTEM BACK PRESSURE NONE - CONSOLE DOWN THROUGH NEUTRAL P1 280-420
MAIN RELIEF ANY EXCEPT SLEW P1 P1 3480 3380-3580