Komatsubulldozersmall ( - d39)

Komatsu DNP031_3C_S(S/N 41001-UP (D31S/Q-20))

Maintenance schedule, common problems & OEM parts breakdown

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The Komatsu DNP031-3C_S (S/N 41001-UP, D31S/Q-20) is a mid-size crawler bulldozer in the D31 series, produced for the North American market. It is powered by a SAA4D102E-2 turbocharged, air-to-air aftercooled diesel engine delivering 56 kW (75 hp) net power. Operating weight ranges from 7,130 kg (15,720 lb) depending on configuration. The DNP031-3C_S succeeded the D31S-20 and D31Q-20 models and was later replaced by the D31EX-20 series. Configurations offered include standard dozer and power angle tilt (PAT) variants.

The DNP031-3C_S represents Komatsu's transition to Tier 4 Interim emissions standards, integrating a Komatsu CARE maintenance program for the first 3 years or 2,000 hours. Its KomStat Hydrostatic Transmission (HST) and SAA4D102E-2 engine are widely supported in the used and parts market, with significant aftermarket availability for undercarriage and hydraulic components. The machine's compact size and high maneuverability make it a staple in utility and municipal work, ensuring steady demand for service parts and rebuild kits.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Komatsu DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) specifications

Engine

ModelSAA4D102E-2
TypeTurbocharged and air-to-air aftercooled diesel
Net Power56 kW (75 HP) @ 2000 rpm

Weights

Operating Weight (D31EX config)7130 kg (15,720 lb)

Dimensions

Transport WidthNot documented for this exact serial range — verify with your dealer
Transport HeightNot documented for this exact serial range — verify with your dealer
Track GaugeNot documented for this exact serial range — verify with your dealer
Track Shoe WidthNot documented for this exact serial range — verify with your dealer
Ground ClearanceNot documented for this exact serial range — verify with your dealer

Performance

Transmission TypeKomStat Hydrostatic Transmission (HST)
Travel Speed (Forward)Not documented for this exact serial range — verify with your dealer
Travel Speed (Reverse)Not documented for this exact serial range — verify with your dealer
Drawbar PullNot documented for this exact serial range — verify with your dealer
GradeabilityNot documented for this exact serial range — verify with your dealer
Ground PressureNot documented for this exact serial range — verify with your dealer

Blades

Blade TypeKomatsu blade geometry (curvature optimized)
Blade CapacityNot documented for this exact serial range — verify with your dealer
Blade WidthNot documented for this exact serial range — verify with your dealer

Service Capacities

Fuel TankNot documented for this exact serial range — verify with your dealer
Hydraulic SystemNot documented for this exact serial range — verify with your dealer
Engine OilNot documented for this exact serial range — verify with your dealer
Cooling SystemNot documented for this exact serial range — verify with your dealer

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

Komatsu DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) maintenance schedule

Service intervalTasks
Every 10 h
  • Check engine oil level and condition
  • Check hydraulic fluid level at sight glass
  • Check coolant level and ensure cap is secure
  • Drain water from fuel separator
  • Check DEF level
  • Inspect air filter restriction indicator
Every 250 h
  • Change engine oil and filter
  • Grease all points including blade, ripper, and push arms
  • Check hydraulic fluid level
  • Inspect air filter outer element
  • Inspect belts, hoses, and clamps
  • Visual undercarriage inspection
Every 500 h
  • Replace fuel filter and drain water separator
  • Replace hydraulic return filter
  • Test battery and alternator
  • Test coolant SCA concentration
  • Collect KOWA hydraulic oil sample
  • Detailed undercarriage wear measurement
Every 1,000 h
  • Replace air filter outer element
  • Change final drive oil on both sides
  • Inspect turbocharger
  • Check valve adjustment
  • Structural inspection of frame and welds
  • Torque ROPS bolts
Every 2,000 h
  • Change hydraulic system oil
  • Flush and replace coolant
  • Service transmission and torque converter
  • Comprehensive component evaluation
  • Inspect and replace worn belts and hoses
  • Torque cutting edge and end bit bolts

Servicing the DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) beyond the schedule

Predictive Maintenance & Fluid Analysis

Utilize KOWA fluid analysis at every 500-hour interval to monitor engine wear metals and hydraulic contamination. Check coolant SCA concentration at 500 hours to prevent scaling in the SAA4D102E-2 engine. Monitor KOMTRAX telematics for load frequency and fuel burn anomalies. Inspect hydraulic hose condition daily for cracks or leaks. Verify transmission oil level at 250 hours to ensure proper HST operation. Track undercarriage wear visually to predict roller and sprocket replacement needs.

Corrective & Common Repairs

Address hydraulic pump leaks common in the D31S/Q-20 series by inspecting seals and fittings. Replace fuel filters and drain the water separator to prevent injector issues in the SAA4D102E-2 engine. Check track tension and adjust if links are binding or sagging excessively. Inspect blade pivot pins and bushings for wear to maintain cutting edge alignment. Replace worn cutting edges and end bits to protect the blade structure. Verify brake function and adjust service/parking brakes as needed.

Overhaul & Rebuild Points

Plan engine overhaul around 10,000 hours based on KOWA results and compression tests. Rebuild the hydraulic pump and final drives when efficiency drops below spec or metal content rises. Inspect the torque converter and transmission components during the 2,000-hour service for wear. Evaluate the undercarriage for elongated links or worn sprocket teeth. Check the turbocharger for shaft play and bearing wear. Assess the structural frame for cracks around high-stress weld points.

Seasonal & Environment Servicing

In cold weather, check coolant freeze protection and use appropriate viscosity engine oil. Drain water from the fuel separator more frequently to prevent icing. In dusty environments, clean the air filter outer element more often and check the restriction indicator. In wet conditions, inspect the radiator and oil cooler fins for debris buildup. Grease all pivot points more frequently in muddy or abrasive conditions. Verify battery charge and terminal condition in extreme temperatures.

DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) common service parts

Part numberPart
195-13-13420FilterCheck fitment →

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DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) fault codes & troubleshooting

CodeMeaningLikely causeWhat to do
CA115Engine crankshaft speed sensor and backup speed sensor failureFaulty speed sensor, broken wiring harness, or corroded connector at the pin connectorReplace the speed sensor and verify voltage at the pin connector
CA111Internal engine controller faultMalfunction within the Electronic Control Module (ECM)Replace or reprogram the ECM
CA451Common rail pressure sensor feedback value too highMalfunction in the rail pressure sensor or actual overpressure condition in the fuel systemDiagnose the fuel rail pressure sensor and check pump lines
CA441Battery voltage too lowWeak battery, failing alternator, or loose connectionsReplace the alternator or battery; check the voltage regulator
CA442Battery voltage too highFailing voltage regulator or alternator overchargingReplace the alternator or battery; check the voltage regulator
CA122Intake air pressure sensor feedback voltage too highFaulty intake pressure sensor or wiring issueVerify the intake pressure sensor and wiring
CA123Intake air pressure sensor feedback voltage too lowSensor short circuit or airflow restrictionCheck for a sensor short or an airflow restriction
CA234Engine overspeedThrottle calibration error, engine load cycle issue, or operator misuseVerify throttle calibration and engine load cycle
AA10NXAir cleaner cloggingDirty or blocked air filter elementReplace the air filter
B@BCNSEngine coolant overheatingLow coolant level, blocked radiator fins, or fan belt failureCheck radiator fins, fan belt, and coolant level

Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.

DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) attachments & work tools

Blades

The DNP031-3C-S (S/N 41001-UP) is based on the D31S/Q-20 platform and supports standard (S), semi-universal (SU), and angle (A) blade configurations, with VPAT availability varying by specific configuration and series. Typical widths and capacities for this class are not explicitly documented in the provided sources; verify with your dealer for exact metric and imperial measurements.

Rippers

Multi-shank and single-shank ripper options are available for this class, with weights varying by configuration and series. Specific shank counts and weight data are not explicitly documented in the provided sources; verify with your dealer for exact specifications.

Winches

Towing winch options for the DNP031-3C-S are not explicitly documented in the provided sources; verify with your dealer for exact class fitment and capacity details.

Drawbars/Counterweights

Drawbar and counterweight specifications for the DNP031-3C-S are not explicitly documented in the provided sources; verify with your dealer for exact weight and mounting details.

Cab/ROPS Guarding

Forestry and waste configuration guarding options for the DNP031-3C-S are not explicitly documented in the provided sources; verify with your dealer for specific ROPS and FOPS guard details.

Hydraulic Arrangement

The DNP031-3C-S utilizes a hydraulic pump compatible with the D31S/Q-20 series, delivering reliable hydraulic power for front and rear tool operation. Specific flow rates and pressure settings for front/reear tool arrangements are not explicitly documented in the provided sources; verify with your dealer for exact hydraulic circuit details.

All DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) assemblies by section

Every catalogued assembly group for the Komatsu DNP031_3C_S(S/N 41001-UP (D31S/Q-20)). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Work Equipment
Komatsu : Dnp031_3c_s(S/N 41001-Up (D31s/Q-20)) : Work Equipment : P.T.O. Case
01***30Bolt,(For France Noise Suppression)4
01***30Bolt,(For Mechanical Governor)2
01***16Bolt, Battery To Frame Ground Wire Attaching2
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Komatsu : Dnp031_3c_s(S/N 41001-Up (D31s/Q-20)) : Work Equipment : P.T.O. Control Lever
01***20Bolt,(With Auto Emergency Steering)3
01***30Bolt,(For Mechanical Governor)1
01***95Bolt,L.H4
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Komatsu : Dnp031_3c_s(S/N 41001-Up (D31s/Q-20)) : Work Equipment : P.T.O. Control Valve
01***20Bolt,(With Auto Emergency Steering)4
01***75Bolt,(For Shipping)4
01***06Nut,(With Back-Up Alarm) (Op), Nut; Was 01580-108061
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Komatsu : Dnp031_3c_s(S/N 41001-Up (D31s/Q-20)) : Work Equipment : P.T.O. Oil Piping
01***25Bolt,Without Revolution Sensor4
01***30Bolt,(For Quick Shift) (Mitsubishi)4
01***25Washer,Spring?For Additional Rear Lam4
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Komatsu : Dnp031_3c_s(S/N 41001-Up (D31s/Q-20)) : Work Equipment : P.T.O. Shaft And Gear
01***20Bolt,(Sandy? Dusty Terrain Spec.)4
01***70Bolt10
01***25Washer,Spring?(Sandy And Dusty Spec.)14
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DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) serial number reference

The Product Identification Number (PIN) plate is located on the front frame casting, typically on the operator's left side near the radiator support. Read the first three characters after the model code (e.g., DNP) to identify the specific build series and configuration prefix.

PrefixIdentifies
DNP031_3C_SDNP031_3C_S(S/N 41001-UP (D31S/Q-20))

Frequently asked questions

What engine does the DNP031-3C_S use?

The DNP031-3C_S (S/N 41001-UP) uses the SAA4D102E-2 turbocharged, air-to-air aftercooled diesel engine.

What is the operating weight?

The operating weight is approximately 7,130 kg (15,720 lb), varying by configuration and attachment.

What model replaced the DNP031-3C_S?

The DNP031-3C_S was succeeded by the D31EX-20 series bulldozer.

What DNP031_3C_S(S/N 41001-UP (D31S/Q-20)) owners discuss

What engine powers the Komatsu DNP031-3C_S (S/N 41001-UP)?
The Komatsu DNP031-3C_S (S/N 41001-UP) utilizes the Komatsu SA6D140E-2 engine. This is a 6-cylinder, water-cooled, turbocharged diesel engine. The SA6D140E-2 is distinct from the engines found in the DNP031-3C_D and DNP031-3C_P variants, which often use different engine families or configurations depending on the specific sub-model and regional emissions requirements. The SA6D140E-2 is known for robust low-end torque suitable for heavy dozing applications. Note that engine specifications can vary slightly by configuration and series; verify the exact engine plate for the specific serial number range 41001-UP against the factory spec sheet for this range.
What are the common hydraulic behaviors and failure patterns for this series?
Operators and mechanics note that Komatsu hydraulic systems are generally smooth and fuel-efficient but can suffer from internal leakage when hot. A common diagnostic pattern is hydraulics working well when cold but becoming weak or sluggish as the oil warms up, indicating worn pump swash plates or main control valve leakage. The line often describes wearing out complete machines simultaneously; if the main hydraulic pump fails, the engine may be near end of service life due to shared contamination or wear cycles. Regular inspection of the main safety valve is critical, as its failure can disrupt the entire hydraulic system. Always check hydraulic oil level and specification before assuming pump failure.
What undercarriage and wear patterns are typical for this bulldozer type?
Undercarriage wear is a primary cost driver for this machine class. Common wear patterns include rapid degradation of track pads, bushings, and bearings due to dust exposure and continuous load. Worn bushings lead to increased noise and vibration, which can accelerate failure of the track chain and rollers. Track tension must be monitored regularly; repeated loosening is common. The undercarriage wears out as a system; inspecting rollers, idlers, and sprockets together is recommended. Ground pressure and track shoe configuration significantly affect wear rates.
What engine quirks are associated with the SA6D140E-2 series?
Engine performance issues often dominate serious problems for this series. Loss of power, increased fuel usage, or overheating may signal airflow restriction, injector wear, or failing fuel delivery components. Contamination, extended service intervals, and low-quality fuel accelerate SA6D140E-2 wear. Overheating can indicate a blocked cooling package (radiator, hydraulic oil cooler, charge-air cooler) or coolant system issues. Engine derating may occur due to aftertreatment system faults, such as KDPF regeneration issues or sensor errors. Check fuel filters and water separators regularly if fuel quality is uncertain. Low oil pressure or level faults can trigger immediate shutdowns.
What are common electrical and sensor issues?
Komatsu equipment relies heavily on electronic control systems, meaning a single faulty sensor or unstable power supply can trigger multiple warning signals. Owners often report intermittent starting, dashboard failures, or random shutdowns. Common sensor errors include crankcase pressure, coolant temperature, intake air temperature, and rail pressure sensors. Electrical issues stem from battery charge voltage problems, alternator malfunctions, or loose grounds. The ECM (Engine Control Module) can experience internal failures or data loss errors. Always verify sensor supply voltages and check for open/short circuits in sensor wiring before replacing sensors. Ensure the battery and charging system are in good condition to prevent erratic electronic behavior.
What should you check when buying a used DNP031-3C_S (S/N 41001-UP)?
When purchasing a used Komatsu DNP031-3C_S (S/N 41001-UP), prioritize these checks: 1) Engine hours and maintenance history for the SA6D140E-2 engine. 2) Hydraulic system performance, testing for weakness when hot. 3) Undercarriage condition, including track tension, roller, idler, and sprocket wear. 4) Electrical system integrity, checking for intermittent faults, sensor errors, and battery/alternator health. 5) Cooling system condition, ensuring no blockages in the radiator or coolers. 6) Verify serial number against factory spec sheet to confirm engine and configuration details.
What safety-critical fixes require dealer verification?
Safety-critical systems requiring dealer verification include the main hydraulic safety valve, engine governor, and aftertreatment system (KDPF/KDOC) components. Repairs involving the ECM, fuel injection system, or braking system should be performed or verified by an authorized dealer. The dealer can verify exact engine and hydraulic specifications for serial number range 41001-UP, as variations exist by configuration and series. Always consult the official Komatsu shop manual for this range for precise safety protocols and specifications.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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