Komatsu D31EX-21, D31PX-21, D37EX-21, D37PX-21, D39EX-21, D39PX-21 Bulldozer Shop Manual (P/N SEBM035005)

This 745-page PDF contains Komatsu shop manual SEBM035005, printed in Japan in November 2007. It covers D31EX-21 and D31PX-21, serial 50501 and up; D37EX-21 and D37PX-21, serial 5501 and up; and D39EX-21 and D39PX-21, serial 1501 and up. All six machines use the SAA4D102E-2-B diesel engine. The repair depth and the need for hydraulic test equipment, electrical adapters, lifting gear, and special service tools make this volume suited to professional technicians and experienced heavy-equipment mechanics.

• HST and steering coverage explains the HPV63+63 tandem pump, safety-suction and charge valves, KMV105 three-speed bent-axis motors, electric steering lever, parking brake controls, and the related pressure, solenoid-output, travel-deviation, and speed-sensor checks.
• EMMS service functions cover model and EX/PX specification setup, steering and brake potentiometer settings, HST pump initialization, engine and decelerator settings, fault-history display, real-time monitoring, and stall-test support after component replacement.
• Fault isolation is divided into displayed error-code diagnosis, electrical E-mode, hydraulic/mechanical H-mode, and engine S-mode. Connector locations, pin tables, T-branch adapter data, fuse maps, and circuit-specific test charts support the checks.
• Major repair procedures address engine/HST pump unit removal, HST motor and final-drive removal, planetary final-drive overhaul, main control valve disassembly, hydraulic-cylinder rebuilding, track work, and idler, recoil-spring, track-roller, and carrier-roller service.
• Work equipment and undercarriage inspection covers CLSS and PPC controls, blade and optional ripper circuits, work-equipment pressure and cylinder-leakage tests, hydraulic bleeding, blade center-ball adjustment, track tension, idler clearance, and component wear limits.
• Factory reference material provides two hydraulic circuit sheets, four electrical circuit sheets, an air-conditioning circuit, eight general torque tables, component-specific tightening data, fluid and lubricant charts, assembly weights, standard values, repair limits, and allowable wear criteria.

Model and Configuration Detail

The specification and standard-value tables separate EX and PX configurations, single-shoe and swamp-shoe undercarriages, standard and narrow blade data, and D31/D37 versus D39 component requirements. Ripper equipment is identified for the EX models, while cab- and canopy-specific electrical, heater, wiper, and air-conditioning systems are called out where applicable. The work-equipment pump is identified as SAR(2)040 on D31/D37 machines and SAR(2)045 on D39 machines, preventing the larger model's data from being applied to the wrong pump.

Testing, Diagnosis, and Repair Depth

Symptom charts go well beyond a basic wiring diagram. Electrical coverage ranges from no-start and preheat faults to monitor, lighting, backup-alarm, heater, air-conditioning, and wiper failures. Hydraulic/mechanical charts isolate no-travel, one-side travel, failed shifting, travel deviation, blade speed or drift, abnormal HST noise, and overheating. Engine charts cover starting, low power, smoke, oil-pressure, cooling, noise, and vibration complaints.

Engine material in this chassis volume covers boost, exhaust temperature and smoke, compression, blow-by, oil-pressure, valve-clearance, and injection-timing checks, plus fuel-system bleeding. Repair procedures include fuel-injection-pump and cylinder-head removal and installation, front and rear crankshaft seal work, and removal of the engine/HST pump assembly. A full internal engine overhaul is outside this volume; Komatsu directs the reader to the separate 102 Series Engine Shop Manual. Internal HST pump and motor overhaul procedures are likewise not included, although their operation, testing, adjustment, and removal are covered.

Tooling, Diagrams, and Shop Cautions

The tool lists tie Komatsu part numbers directly to specific jobs. Examples include the 791T-265-1110 HST motor speed-sensor wrench, 791-427-1410 final-drive round-nut wrench, 791-685-8006 recoil-spring compressor, and 790-502-1003 hydraulic-cylinder repair stand, along with sketches for locally made idler and track-roller bushing tools. Visual references include the HST hydraulic-equipment arrangement, HST pump and KMV105 motor section views, the two-stage planetary final drive, CLSS operation diagrams, system connector layouts, and the complete hydraulic/electrical circuit set. AV, AVS, and AEX wire codes and color conventions are also defined.

The manual flags two easy ways to turn a repair into a parts problem: using an impact wrench on the oil-cooler cleaning-cover bolt can break its pin, and removing the cooler with that cover installed can let the pin damage the core. During final-drive assembly, an incompletely seated hub bearing can damage the mating floating-seal faces.

Before opening the HST or work-equipment circuit, the machine must be secured and residual hydraulic pressure released. Track, recoil-spring, blade, and powertrain work requires rated lifting or pressing equipment, and R134a recovery and charging is reserved for qualified personnel.