PDF Service Manual Bobcat 753 G-Series Skid Steer Loader - 4 MB
The complete service manual for the popular Bobcat 753 G-Series skid steer loader.
This guide offers detailed, step-by-step instructions for all repair and maintenance procedures.
With sections on hydraulics, hydrostatic system, and engine service, it's the definitive resource for technicians.
Keep your 753 running like new with this factory manual.
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--- Page 1 ---
Service
Manual
G Series
(S/N 515830001 & Above)
(S/N 516220001 & Above)
EQUIPPED WITH
BOBCAT INTERLOCK
CONTROL SYSTEM (BICS™)
6900976 (2-06) Printed in U.S.A. © Bobcat Company 2006
--- 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 • An Operator’s Handbook fastened to the operator
instructions 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.
WARNING • The AEM Safety Manual delivered with the machine
gives general safety information.
Warnings on the machine and in the manuals are for
your safety. Failure to obey warnings can cause • The Service Manual and Parts Manual are available
injury or death. from your dealer for use by mechanics to do shop-
W-2044-1285 type service and repair work.
• The Skid-Steer Loader Operator Training Course is
available through your local dealer or at
IMPORTANT www.training.bobcat.com or www.bobcat.com.
This course is intended to provide rules and practices
of correct operation of the Skid-Steer Loader. The
This notice identifies procedures which must be
course is available in English and Spanish versions.
followed to avoid damage to the machine.
I-2019-0284
• 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.
• The Skid-Steer Loader Safety Video is available from
your Bobcat dealer or at www.training.bobcat.com
or www.bobcat.com.
SI SSL-0206 SM
753 Bobcat Loader
V Service Manual
--- Page 4 ---
LIFT ARM SUPPORT DEVICE Figure 10-20-1
Installing Lift Arm Support Device
1
2
WARNING P-31849 N-20526
Never work on a machine with the lift arms up unless
the lift arms are secured by an approved lift arm Put jackstands under the rear corners of the loader frame
support device. Failure to use an approved lift arm (Inset) [Figure 10-20-1].
support device can allow the lift arms or attachment
to fall and cause injury or death. Disconnect the spring from the lift arm support device
W-2059-0598 retaining pin (Item 1). Support the lift arm support device
(Item 2) [Figure 10-20-1] with your hand and remove the
retaining pin.
WARNING Figure 10-20-2
Service lift arm support device if damaged or if parts
are missing. Using a damaged lift arm support or
with missing parts can cause lift arms to drop
causing injury or death. 1
W-2271-1197
N-20525
Lower the lift arm support device on top of the lift
cylinder. Hook the free end of the spring (Item 1) [Figure
10-20-2] to the lift arm support device so there will be no
interference with the support device engagement.
With the operator in the seat, seat belt fastened and seat
bar lowered, start the engine.
753 Bobcat Loader
10-20-1 Service Manual
--- Page 5 ---
REMOTE START Figure 10-60-3
Procedure
Figure 10-60-1
1
1
P-28823
Lift and block the loader. (See LIFTING AND BLOCKING
N-20862 THE LOADER on Page 10-10-1.)
Raise the lift arms (if required by the procedure) and
The tool listed will be needed to do the following install an approved lift arm support device. (See Installing
procedure: Lift Arm Support Device on Page 10-20-1.)
MEL1563: Remote Start Tool Kit Raise the operator cab (if required by the procedure).
(See Raising The Operator Cab on Page 10-30-1.)
The remote start (Item 1) [Figure 10-60-1] is required
when the operator cab is in the raised position for service Open the rear door of the loader.
and the service technician needs to turn the key switch
on or start the engine. Example: adjusting the steering Remove the plug (Item 1) [Figure 10-60-2] /or
linkage. disconnect the attachment control harness (Item 1)
[Figure 10-60-3] if connected.
Figure 10-60-2
1
P-28793
753 Bobcat Loader
10-60-1 Service Manual
--- Page 6 ---
ENGINE COOLING SYSTEM Figure 10-90-2
WARNING
Wear safety glasses to prevent eye injury when any
of the following conditions exist:
• When fluids are under pressure.
• Flying debris or loose material is present.
• Engine is running.
• Tools are being used.
W-2019-1285
Check the cooling system every day to prevent over- N-20594
heating, loss of performance or engine damage.
Cleaning The Cooling System Raise the oil cooler. Clean the top of the radiator [Figure
10-90-2].
Figure 10-90-1
NOTE: Use low air pressure or low water pressure to
clean the radiator or damage to the radiator
fins may result.
Lower the oil cooler.
Check cooling system for leaks.
Lower the rear grill and close the rear door.
Checking The Coolant Level
Figure 10-90-3
N-20595
Open the rear door and raise the rear grill.
Use air pressure or water pressure to clean the top of the
oil cooler [Figure 10-90-1].
1
WARNING
Do not use your bare hands to remove debris from
the oil cooler. Cooling fins are sharp and may cause P-43238
injury.
W-2460-0303
Open the rear door.
Remove the cover from the coolant recovery tank (Item
1) [Figure 10-90-3]. Check the coolant level. The coolant
level must be between the MIN and MAX marks on the
coolant recovery tank when the engine is cold.
Close the rear door before operating the loader.
753 Bobcat Loader
10-90-1 Service Manual
--- Page 7 ---
HYDRAULIC/HYDROSTATIC SYSTEM Figure 10-120-3
Checking And Adding Fluid
Figure 10-120-1
2
1
P-28802
Remove the screen and clean with solvent as needed
P-43245 [Figure 10-120-3].
Install the fill cap.
Use only recommended fluid in the hydraulic system.
(See HYDRAULIC FLUID SPECIFICATIONS on Page Replacing Hydraulic/Hydrostatic Filter
SPEC-50-1.)
Figure 10-120-4
Stop the loader on a level surface,
Lower the lift arms and tilt the Bob-Tach fully back.
Stop the engine.
1
Remove the dipstick (Item 1) [Figure 10-120-1] and
check the fluid level.
Remove the fill cap (Item 2) [Figure 10-120-1].
Figure 10-120-2
P-28794
(See SERVICE SCHEDULE on Page 10-70-1.) for the
1 correct service intervals.
Open the rear door.
Remove the filter element (Item 1) [Figure 10-120-4].
Clean the gasket sealing surface on the filter housing.
Put clean oil on the seal of the new filter element.
P10303
Install and hand tighten the filter element.
Add the correct fluid to the reservoir until the fluid level is Close the rear door before operating the loader.
between the marks on the dipstick (Item 1) [Figure 10-
120-2]. Do not fill above the top mark on the dipstick Start the engine, check for leaks and the proper fluid level
in the reservoir.
753 Bobcat Loader
10-120-1 Service Manual
--- Page 8 ---
POWER BOB-TACH Figure 10-151-3
Inspection And Maintenance
Figure 10-151-1
2
1
1
P-43832
2
Push and hold the BOB-TACH “WEDGES DOWN” switch
B-15891 (Item 2) [Figure 10-151-1], until the wedges (Item 1) and
levers (Item 2) [Figure 10-151-3] are fully down.
Figure 10-151-2 The levers and wedges must move freely.
WARNING
Bob-Tach wedges must extend through the holes in
attachment. Levers must be fully down and locked.
2 Failure to secure wedges can allow attachment to
come off and cause injury or death.
W-2102-0588
1
P-43831
Push and hold the BOB-TACH “WEDGES UP” switch
(Item 1) [Figure 10-151-1], until the wedges (Item 1) and
levers (Item 2) [Figure 10-151-2] are fully raised.
753 Bobcat Loader
10-151-1 Service Manual
--- Page 9 ---
HYDRAULIC SYSTEM
BUCKET POSITION VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-90-1
Disassembly And Assembly 20-90-3
Removal And Installation 20-90-2 HYDRAULIC
Solenoid Removal And Installation . . . . . . . . . . . . . . . . . . . .20-90-1 SYSTEM
Solenoid Testing 20-90-1
CYLINDER (LIFT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-20-1
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-20-5
Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-20-1
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-20-4
Identification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-20-3 DRIVE
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-20-2 SYSTEM
CYLINDER (POWER BOB-TACH) . . . . . . . . . . . . . . . . . . . . . . .20-22-1
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-22-5
Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-22-1
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-22-4
Parts Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-22-3
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-22-2 ELECTRICAL
SYSTEM &
CYLINDER (TILT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-21-1 ANALYSIS
Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-21-6
Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-21-1
Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-21-5 ENGINE
Identification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-21-4 SERVICE
Removal And Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-21-1
Rod End Pivot Pin Bushing And Seal Replacement . . . . . . .20-21-3
FRONT AUXILIARY HYDRAULIC COUPLER BLOCK. . . . . . .20-121-1 SPECIFICATIONS
Disassembly And Assembly. . . . . . . . . . . . . . . . . . . . . . . . .20-121-1
Removal and Installation (S/N 515842310 & Above). . . . . .20-121-1
FRONT AUXILIARY PRESSURE RELIEF BLOCK. . . . . . . . . .20-120-1
Disassembly And Assembly (S/N 515842309 and Below) .20-120-2
Removal And Installation (S/N 515842309 and Below) . . . .20-120-1
Solenoid Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-120-3
Solenoid Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-120-3
Continued On Next Page
753 Bobcat Loader
20-01 Service Manual
--- Page 10 ---
HYDRAULIC SYSTEM INFORMATION (CONT’D)
Glossary Of Hydraulic/Hydrostatic Symbols (Cont’d)
753 Bobcat Loader
20-10-3 Service Manual
--- Page 11 ---
CYLINDER (LIFT) (CONT’D) Figure 20-20-18
Assembly (Cont'd)
Figure 20-20-17
3
4
2
1
P7429
5
Put the base end of the hydraulic cylinder in a vise.
N-20552
Tighten the head using a spanner wrench [Figure 20-20-
18].
Install the head (Item 1), and spacer (Item 2) [Figure 20-
20-17].
Install the piston (Item 3) [Figure 20-20-17].
NOTE: The piston center hole (Item 5) [Figure 20-20-
17] has a bevel on one end. The bevel goes
toward the rod.
Grease the piston where the nut contacts the piston. Do
not get grease on the threads. Install the new nut (Item 4)
[Figure 20-20-17].
Tighten the nut (Item 4) [Figure 20-20-17] to 300 ft.-lbs.
(407 Nm) torque.
753 Bobcat Loader
20-20-7 Service Manual
--- Page 12 ---
CYLINDER (POWER BOB-TACH)
Checking
WARNING
Figure 20-22-1
Always clean up spilled fuel or oil. Keep heat, flames,
sparks or lighted tobacco away from fuel and oil.
Failure to use care around combustibles can cause
explosion or fire which can result in injury or death.
W-2103-1285
WARNING
1 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.
P-31514
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
Tilt the Bob-Tach forward, so it is parallel to the floor from a physician familiar with this injury.
[Figure 20-22-1]. W-2072-0496
Disconnect the hose (Item 1) [Figure 20-22-1] from the
power Bob-Tach cylinder base end port.
Figure 20-22-2
1
2
P-43211
Install a plug in the hose (Item 1) [Figure 20-22-2] and
tighten.
Engage the parking brake. Lower the seat bar. Start the
engine.
Push and hold the BOB-TACH “WEDGES UP” Switch
(Front Accessory Panel).
If there is any leakage from the base end cylinder port
(Item 2) [Figure 20-22-2], remove the lift cylinder for
repair.
753 Bobcat Loader
20-22-1 Service Manual
--- Page 13 ---
MAIN RELIEF VALVE (CONT’D)
Removal and Installation
Figure 20-30-6
1
N-20909
Remove the four motor cover mounting bolts (Item 1)
[Figure 20-30-6].
Clean the area around the control valve. Loosen and
remove the main relief valve (Item 1) [Figure 20-30-7].
Remove the O-rings and back-up washers [Figure 20-
30-5].
Clean the main relief valve in clean solvent. Use air
pressure to dry the valve.
Figure 20-30-7
1
N-20907
Install new O-rings and back-up washers. Install the main
relief valve (Item 1) [Figure 20-30-7] and tighten. Check
the pressure again. (See MAIN RELIEF VALVE
(CONT’D) on Page 20-30-3.)
Installation: Tighten the main relief valve to 35-40 ft.-lbs.
(47-54 Nm) torque.
753 Bobcat Loader
20-30-3 Service Manual
--- Page 14 ---
HYDRAULIC CONTROL VALVE (FOOT CONTROL) Figure 20-40-29
(CONT’D)
Removal And Installation (S/N 515840212 & Above)
(Cont'd)
Figure 20-40-27
1
2 1
P-43310
Remove the two control valve mounting bolts/nuts (Item
1) [Figure 20-40-29] from the loader frame.
P-43309 Installation: Tighten the mounting bolt & nut to 18-20 ft.-
lbs. (24-27 Nm) torque.
Remove the access covers (Items 1 & 2) [Figure 20-40-
27] on the right side of the loader frame.
Figure 20-40-28
P-43308
Disconnect the inlet hose from the control valve through
the access slot [Figure 20-40-28].
753 Bobcat Loader
20-40-9 Service Manual
--- Page 15 ---
HYDRAULIC CONTROL VALVE (FOOT CONTROL) Anti-Cavitation Valve
(CONT’D)
Figure 20-40-60
Port Relief Valve
Figure 20-40-58
1
1
N-21013
N-21013 Remove the anti-cavitation valve (Item 1) [Figure 20-40-
60] (Port E2) from the control valve for the tilt section.
Loosen the port relief valve (Item 1) [Figure 20-40- Installation: Always use new O-rings and back-up
58](Port E1). washers. Tighten to 35-40 ft.-lbs. (47-54 Nm) torque.
Installation: Always use new O-rings and back-up
washers. Tighten to 35-40 ft.-lbs. (47-54 Nm) torque.
Remove the port relief valve.
Figure 20-40-59
4
3
2
1
1. O-ring
2. Backup Washer
3. O-ring
4. Relief Valve
N-18844
Remove the O-rings and back-up washer from the port
relief valve [Figure 20-40-59].
753 Bobcat Loader
20-40-19 Service Manual
--- Page 16 ---
HYDRAULIC CONTROL VALVE (FOOT CONTROL) Figure 20-40-97
(CONT’D)
Lift Spool and Detent (Cont'd)
Figure 20-40-95
2
CD-15051
1
Install the detent balls and spring [Figure 20-40-97].
N-18917 Figure 20-40-98
Install the spool seal (Item 1) and back-up washer (Item
2) [Figure 20-40-95].
Figure 20-40-96
1
N-19007
Hold the detent balls in place with the detent pliers
[Figure 20-40-98].
N-19005
Install the spring assembly to the lift spool hand tight
[Figure 20-40-96].
Remove the spring tool.
Check the alignment of the detent adapter and the
washer.
Tighten the adapter to 90-100 in.-lbs. (10,2-11,3 Nm).
NOTE: The adapter must fit in the center of the
washer (Item 1) [Figure 20-40-96].
753 Bobcat Loader
20-40-29 Service Manual
--- Page 17 ---
HYDRAULIC CONTROL VALVE (ADVANCED Figure 20-41-9
CONTROL SYSTEM) (ACS) (CONT'D)
Removal And Installation (S/N 515840211 & Below)
(Cont’d) 1 1
Figure 20-41-7
1
P-28897
Locate the access covers (Item 1) [Figure 20-41-9] on
the right side of the loader frame.
P-28895 Figure 20-41-10
Remove the two mounting bolts (Item 1) [Figure 20-41- 1
7] from the lift arm by-pass control bracket.
Figure 20-41-8
P-28899
Remove the drive motor cover [Figure 20-41-10].
Loosen the rear mounting bolt and remove the front
N-21145 mounting bolt from the rectangular access cover (Item 1)
[Figure 20-41-10].
Connect a hoist to the control valve [Figure 20-41-8]. Rotate the cover to expose the access slot in the loader
[Figure 20-41-10].
753 Bobcat Loader
20-41-3 Service Manual
--- Page 18 ---
HYDRAULIC CONTROL VALVE (ADVANCED Figure 20-41-44
CONTROL SYSTEM) (ACS) (CONT'D)
BICS™ Valve, Solenoid Removal and Installation
1
Figure 20-41-42
1
2
N-18692
Remove the solenoid cartridge (Item 1) [Figure 20-41-
44].
N-18691
Installation: Tighten the cartridge to 20 ft.-lbs. (27 Nm)
torque.
Remove the mounting nut (Item 1) [Figure 20-41-42]
from the solenoid cartridge.
Installation: Tighten the mounting nut to 53 in.-lbs. (6
Nm) torque.