Kubota U20-3, U25-3, and U25S Workshop Manual — 97899-61500

About this manual

Kubota published this Workshop Manual for the U20-3, U25-3, and U25S excavator models. It brings the documented service and technical-reference material for those named excavators into a single publication.

The manual is especially useful for work that crosses electrical and hydraulic systems: it includes electrical troubleshooting, alongside hydraulic diagrams, pressure-test evidence, and valve-adjustment information.

Use the Manual Contents below to check that the exact repair, inspection, or maintenance procedure you need is included in this publication.

Manual details

Manufacturer

Kubota

Manual type

Workshop Manual

Models

U20-3, U25-3, and U25S

Document number

97899-61500

Language

English

Page count

478

Product highlights

Electrical systems

The manual includes electrical troubleshooting and pinouts.

Hydraulic systems

The manual includes hydraulic circuit diagrams, hydraulic pressure-test material, and hydraulic valve-adjustment material.

Specifications and settings

The manual includes reference information for torque specifications.

Special tools

A special-tools section is included.

Maintenance

The manual includes a lubrication chart.

Manual contents

Use these source headings to locate the task or system you need in the PDF.

• CONTENTS — p. 2
  • I General — p. 4
    • A.Body and engine identification marks — p. 6
    • B.Safety precautions for servicing, disassembly and reassembly — p. 7
    • C.IMPORTANT SAFETY PROCESS AND CRITICAL FUNCTIONAL PROCESS — p. 9
    • D.IMPORTANT INSPECTION ITEMS AFTER REASSEMBLING — p. 9
    • E.SERVICING FUNDAMENTALS — p. 10
    • F. Maintenance intervals — p. 19
      • a. Maintenance intervals chart : EU-version — p. 19
      • b.Maintenance intervals chart : PP-version — p. 20
      • c.Water and oil quantity — p. 22
      • d.Recommended oil — p. 23
      • e Hydraulic Oil Check for machines with Hydraulic Breakers — p. 24
      • f. Periodic replacement of important parts — p. 26
  • II Machine Body — p. 28
    • A.Specifications — p. 30
      • a. Machine weight — p. 30
      • b. Machine specifications — p. 31
      • c. Lever stroke and operating force — p. 32
      • d. Dimensions of parts — p. 33
        • [1] Front pins — p. 33
        • [2] Bucket — p. 34
        • [3] Rubber crawler — p. 36
        • [4] Iron crawler — p. 36
        • [5] Track roller, idler, and sprockett — p. 37
        • [6] Dozerr — p. 38
        • [7] Parts weight — p. 39
        • [8] Water and oil quantity — p. 40
    • B.Front attachment — p. 41
      • a. Parts designation — p. 41
      • b. Exchange of bucket (Kubota Japan Bucket) — p. 44
      • c. Exchange of bucket teeth and side cutters [JPN bucket version] — p. 45
      • d. Installing of dust seal and thrust collar — p. 46
      • e. Installation of pin and bush — p. 47
        • [1] Pin bush — p. 47
        • [2] Pin, bush-(2) — p. 49
        • [3] Front bucket mounting instruction (PP-version) — p. 51
      • f. Front hose — p. 52
        • [1] Front hose assembly (U20-3α) — p. 52
        • [2]Front hose assembly (U25-3α, U25S) — p. 53
        • [3] Hose clamp — p. 54
        • [4] Front hose control valve side — p. 54
    • C.Upper structure — p. 55
      • a. Lever and pedal — p. 55
        • [1] Travel lever — p. 55
        • [2] Acceleration lever — p. 60
        • [3] Blade lever — p. 64
        • [4] Swing pedal — p. 65
        • [5]Service port pedal — p. 66
        • [6] Limit switch — p. 68
      • b Counterweight — p. 69
    • D.Cab / canopy installation — p. 70
      • a. Installing the cabin or canopy — p. 70
        • [1] Installing the cabin — p. 70
        • [2] Canopy installation — p. 72
        • [3]Floor Mat — p. 73
        • [4] Heater setup — p. 74
        • [5]Defroster setup — p. 75
        • [6] Thermal insulation and sound absorber — p. 76
        • [7] Seat and seat belt — p. 85
        • FYI (For your information) — p. 86
        • [8] Boom cylinder for cab type — p. 88
        • [9] Outlook of covers — p. 89
    • E. Under carriage — p. 90
      • a Swivel bearing — p. 90
      • b Grease tube — p. 90
      • c Track tension device — p. 91
      • d Upper roller and track roller — p. 93
      • e. Crawler replacement and tension adjustment procedure — p. 97
    • F. Variable track (U20-3α) — p. 100
      • a. Dimensional view — p. 100
      • b.Service data — p. 101
      • c. Track frame — p. 102
      • d. Blade — p. 104
      • e. Track cylinder — p. 106
      • f. Blade cylinder — p. 108
      • g. Hydraulic hose — p. 109
      • h. Control valve — p. 113
      • i. Swivel joint — p. 114
      • j. Track control lever — p. 116
      • k. Counterweight — p. 117
    • G. Label — p. 118
  • III Engine — p. 128
    • III-1 Engine specifications for construction machinery — p. 130
    • III-2 Engine mount on the construction machinery — p. 132
      • A. Engine bracket — p. 132
      • B. Radiator — p. 133
        • [1] Detaching the radiator — p. 133
        • [2] Reassembling the radiator — p. 134
      • C. Muffler — p. 137
        • [1] Reassembling procedure — p. 137
      • D. Fan belt — p. 138
      • E. Air cleaner — p. 139
      • F. Fuel tank and hose — p. 140
    • III-3. 05-M Series Engine WSM-General — p. 148
    • III-4. Engine WSM (Mechanism section) — p. 152
      • A.Feature — p. 154
      • B.Engine body — p. 155
        • [1]Cylinder block — p. 155
        • [2]Cylinder head — p. 155
        • [3]Crankshaft — p. 156
        • [4]Piston and piston rings — p. 156
        • [5]Connecting rod — p. 157
        • [6]Rocker arm — p. 157
        • [7]Camshaft — p. 157
        • [8]Fuel camshaft — p. 158
        • [9]Flywheel — p. 158
      • C.Lubricating system — p. 159
        • [1]General — p. 159
        • [2]Oil pump — p. 160
        • [3]Relief valve — p. 160
        • [4]Oil filter cartridge — p. 161
        • [5]Oil pressure switch — p. 161
      • D.Cooling system — p. 162
        • [1]General — p. 162
        • [2]Water pump — p. 162
        • [3]Thermostat — p. 163
        • [4]Radiator (not included in the basic engine) — p. 163
        • [5]Radiator cap — p. 164
      • E.Intake / exhaust system — p. 165
        • [1]Air cleaner (not included in the basic engine) — p. 165
        • [2]Muffler (not included in the basic engine) — p. 165
      • F. Fuel system — p. 166
        • [1]General — p. 166
        • [2] Injection pump — p. 166
        • [3] Injection nozzle — p. 169
        • [4]Fuel filter (not included in the basic model) — p. 169
        • [5]Governor — p. 170
      • G.Electrical system — p. 172
        • [1]Charging system — p. 172
    • III-5. Engine WSM (Service section) — p. 174
      • A.Engine mount on the machine — p. 174
      • B.General — p. 176
        • [1]Engine identification — p. 176
        • [2]General precaution — p. 177
        • [3]Tightening torques — p. 178
        • [4]Troubleshooting — p. 179
        • [5]Servicing specifications — p. 182
        • [6]Maintenance check list — p. 191
        • [7]Check and maintenance — p. 192
      • C.Engine body — p. 205
        • CHECKING AND ADJUSTING — p. 205
        • DISASSEMBLING AND ASSEMBLING — p. 206
          • [1]Draining water and oil — p. 207
          • [2]External components — p. 207
          • [3]Cylinder head and valves — p. 208
          • [4]Gear case — p. 210
          • [5]Piston and connecting rod — p. 216
          • [6]Flywheel and crankshaft — p. 219
        • SERVICING — p. 221
          • [1]Cylinder head — p. 221
          • [2]Timing gear and camshaft — p. 226
          • [3]Piston and connecting rod — p. 228
          • [4]Crankshaft — p. 231
          • [5]Cylinder — p. 237
      • D.Lubricating system — p. 239
        • CHECKING — p. 239
        • SERVICING — p. 239
          • [1]Oil pump — p. 239
      • E.Cooling system — p. 241
        • CHECKING — p. 241
          • [1]Fan belt — p. 241
          • [2]Radiator — p. 241
        • DISASSEMBLING AND ASSEMBLING — p. 242
      • F. Fuel system — p. 244
        • CHECKING AND ADJUSTING — p. 244
          • [1] Injection pump — p. 244
          • [2] Injection nozzle — p. 246
        • DISASSEMBLING AND ASSEMBLING — p. 247
          • [1] Injection pump — p. 247
          • [2] Injection nozzle — p. 248
      • G.Electrical system — p. 249
        • CHECKING — p. 249
          • [1]Starter — p. 249
          • [2]Glow plug — p. 250
        • DISASSEMBLING AND ASSEMBLING — p. 250
          • [1]Starter — p. 250
          • [2]Alternator — p. 251
        • SERVICING — p. 254
          • [1]Starter — p. 254
          • [2]Alternator — p. 256
      • H.Turbo charger system — p. 259
        • CHECKING — p. 259
        • DISASSEMBLING AND ASSEMBLING — p. 261
  • IV.Hydraulic system (Service section) — p. 264
    • A.Troubleshooting — p. 266
      • a. Common Circuit — p. 266
      • b. Hydraulic system and front attachment — p. 268
      • c. Pump — p. 270
      • d. Motor — p. 271
      • e. Swivel performance — p. 272
      • f. Traveling performance — p. 278
    • B.Specifications — p. 282
      • a. Pump — p. 282
        • [1] Specifications — p. 282
        • [2] Piston pump P-Q performance curve (Theoretical) — p. 284
      • b. Relief valve — p. 286
        • [1] Location — p. 286
        • [2]Main relief valve (bench data) — p. 287
        • [3]Main relief valve (at the measurement port on the machine) — p. 287
        • [4]Pilot system pressure — p. 287
        • [5]Overload relief valve (bench data) — p. 288
        • [6]Overload relief valve (at the measurement port on the machine) — p. 288
      • c.Swivel performance — p. 289
      • d.Traveling performance — p. 290
      • e. Cylinder — p. 292
        • [1] Specifications and dimensions listt — p. 292
        • [2] Speed — p. 294
        • [3] Natural fall — p. 294
        • [4] Cylinder list — p. 295
    • C.Testing — p. 303
      • a. Pump flow — p. 303
      • b. Pressure measurement — p. 304
        • [1] Pilot pressure — p. 304
        • [2] Main relief valve pressure — p. 305
        • [3] Overload relief pressure — p. 307
        • [4] Swivel brake pressure — p. 308
        • [5] Swivel brake release valve — p. 309
        • [6] Travel two-speed selector pressure — p. 309
      • c. Drain measurement — p. 310
        • [1] Travel motor — p. 310
        • [2] Swivel motor — p. 311
      • d. Measurement of block performance — p. 312
        • [1] Swivel — p. 312
        • [2] Travel — p. 312
      • e. Operating speed — p. 313
        • [1] Checking procedure of each speed — p. 313
      • f. Straight travel performance — p. 315
      • g. Control and traveling lever operating force — p. 315
      • h. Control and traveling lever stroke — p. 315
      • i. Cylinder natural fall amount — p. 315
    • D.Disassembling and Assembling — p. 316
      • a. Pump — p. 316
        • [1] Pump coupling — p. 316
        • [2] Mounting and dismounting the pump — p. 318
        • [3]Component parts of pump — p. 320
        • [4]Disassembling and reassembling the pump. — p. 321
        • [5]Troubleshooting of pump — p. 327
      • b. Control valve — p. 328
        • [1]Mounting and dismounting the valve — p. 328
        • [2] Disassembling and reassembling the valve — p. 331
        • [3] Component parts of sections — p. 332
      • C. Pilot valve — p. 339
        • [1] Mounting and dismounting the pilot valve 1) — p. 339
        • [2] Disassembling and reassembling the pilot valve — p. 343
      • d. Swivel motor — p. 355
        • [1] Mounting and dismounting the swivel motor — p. 355
        • [2] Swivel motor mounting/dismounting component parts — p. 357
        • [3] Disassembling and reassembling the swivel motor — p. 362
      • e. Rotary joint (Swivel joint) — p. 372
      • f. Traveling motor — p. 376
        • [1] Mounting and dismounting the wheel motor — p. 376
        • [2] List of adapter hoses — p. 377
        • [3] Component parts of wheel motor (Kayaba-make) — p. 378
        • [4] Disassembling and reassembling the wheel motor — p. 381
      • g.Cylinder — p. 407
      • h. Hydraulic hose — p. 412
        • [1] Delivery hose — p. 412
        • [2] Delivery hose routing — p. 413
        • [3] Blade / travel hose — p. 416
        • [4] Pilot hose — p. 419
      • i. Other hydraulic valve — p. 424
        • [1] Selector valve — p. 424
        • [2] Pilot filter — p. 427
        • [3] TPSS valve, PP-version — p. 428
        • [4] Accumulator — p. 430
        • [5] Third line valve — p. 432
  • V.Electrical system (Service section) — p. 434
    • A.Specifications — p. 436
    • B Troubleshooting — p. 439
      • a Engine — p. 439
      • b Meter panel — p. 440
      • c Others — p. 442
      • d Check instructions — p. 443
        • [1] Fuse — p. 443
        • [2] Battery voltage — p. 444
        • [3] Automatic release relay — p. 444
        • [4] Release controller — p. 445
        • [5] Starter motor — p. 445
        • [6] Key switch — p. 446
        • [7] Fuel pump coupler — p. 446
        • [8] Engine stop solenoid — p. 447
        • [9] Glow relay — p. 447
        • [10] Charge and engine oil lamp — p. 449
        • [11] Water temperature gauge — p. 450
        • [12]Fuel sensor — p. 450
        • [13]Solenoid valve — p. 451
        • [14]Horn — p. 454
        • [15]working light — p. 455
    • C Wireharness installation — p. 456
      • a Front wireharness — p. 457
      • b Wireharness around engine — p. 458
      • C Swivel frame wireharness — p. 462
      • d. Wireharness around battery — p. 465
      • e Wireharness around seat — p. 467
• Conversion Tables — p. 473

Capabilities

The source outline indexes servicing instructions, disassembly and assembly, maintenance tasks, checking and adjustment, mechanism explanations, and troubleshooting. Use these source-backed headings to locate the applicable task or system in the source PDF, then confirm model-specific notes, specifications, illustrations, and operating conditions at the relevant page before carrying out service work.

Keep the source's safety sequence, prerequisite steps, labels, units, configuration notes, and footnotes with the selected task; do not apply an isolated value outside the conditions stated in the manual.

Technical reference

Reference tables include torque settings for service checks, adjustment work, and specification lookup. Use the values and conditions in the PDF for the applicable model and procedure.

• Service limits and settings: torque settings.

Delivery

This manual is supplied as a digital PDF file and is available for instant download after purchase. No physical media is shipped.

References

Kubota Workshop Manual for Excavator, document code 97899-61500, PDF edition.