Komatsu S6D125-1M(S/N 11574-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu S6D125-1M (S/N 11574-UP) is a turbocharged, aftercooled, six-cylinder diesel engine belonging to the Komatsu 125 series. It powers heavy-duty construction equipment including the D65E-12, D65P-12, D65EX-12, and D65PX-12 bulldozers, as well as PC400-6 and PC400LC-6 excavators and WA380 wheel loaders. Production spans from the late 1990s through the 2010s, with operating weights for the host machines ranging from approximately 31,600 mm (103,675 lb) to 34,500 mm (113,190 lb) depending on configuration. The S6D125-1M succeeded earlier naturally aspirated 6D125 variants and was later replaced by the S6D125E-2 series to meet evolving emissions standards.
Across generations, the primary change from the 6D125-1 to the S6D125-1M was the addition of forced induction via turbocharging and aftercooling, which increased torque rise by 13% to 30% depending on the specific horsepower rating (155 HP or 180 HP). This engine remains critical in the used and parts market because of its widespread installation in the D65 and PC400 series, which dominate the secondary market. Its robust wet liner design and mechanical fuel system make it a preferred candidate for rebuild, while the specific S/N 11574-UP designation ensures accurate parts cataloging for owners of later-production units in this generation.
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 S6D125-1M(S/N 11574-UP) specifications
Engine
| Model | S6D125-1M |
| Series | S6D125 (125 series) |
| Configuration | Turbocharged and aftercooled |
| Cylinders | 6 |
| Displacement | 11 L (672 cu in) |
| Gross Power | 205 kW (275 HP) |
| Torque | 1,010 lbf·ft (1,370 N·m) |
| Emissions Tier | Not documented for this exact serial range — verify with your dealer |
Weights
| Operating Weight | Not documented for this exact serial range — verify with your dealer |
| Shipping Weight | Not documented for this exact serial range — verify with your dealer |
| Ground Pressure | Not documented for this exact serial range — verify with your dealer |
Dimensions
| Transport Length | Not documented for this exact serial range — verify with your dealer |
| Transport Width | Not documented for this exact serial range — verify with your dealer |
| Transport Height | Not documented for this exact serial range — verify with your dealer |
| Track Gauge | 1,880 mm (74.0 in) or 2,050 mm (80.7 in) |
| Ground Clearance | 400 mm (15.7 in) or 510 mm (20.1 in) |
Performance
| Travel Speeds | Not documented for this exact serial range — verify with your dealer |
| Gradeability | Not documented for this exact serial range — verify with your dealer |
Service capacities (summary)
| Fuel Tank | Not documented for this exact serial range — verify with your dealer |
| Hydraulic System | Not documented for this exact serial range — verify with your dealer |
| Engine Oil | Not documented for this exact serial range — verify with your dealer |
| Cooling System | Not 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 S6D125-1M(S/N 11574-UP) maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
Servicing the S6D125-1M(S/N 11574-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Monitor KOWA oil analysis results at every 500-hour interval to track wear metals (iron, copper, lead) and contaminants (silicon, sodium). Check coolant SCA concentration regularly to prevent cavitation pitting in the wet cylinder liners. Inspect the air filter restriction indicator daily; shorten service intervals in dusty environments. Log trends for charge pressure and torque converter oil temperature to detect turbo or transmission issues before failure. Verify hydraulic oil particle count and viscosity during major services to protect pump and valve integrity.
Corrective & Common Repairs
Address coolant leaks into the crankcase by inspecting wet liner O-rings and cylinder head gaskets, often caused by depleted SCA additives. Replace worn steering clutch and brake linings in the final drive units, which are prone to contamination-driven wear. Fix hydraulic control valve assembly leaks that double as the tank seal. Inspect splash-lubricated final drive gear sets for contamination. Check for steam from the breather on startup, indicating coolant intrusion. Replace worn piston rings and rod bushings if blow-by exceeds limits.
Overhaul & Rebuild Points
Perform in-frame overhaul when compression drops or blow-by increases significantly. Replace piston assemblies, piston pins, snap rings, and rod bushings. Inspect cylinder liners for scoring or wear beyond limits. Replace main bearings, rod bearings, and thrust bearings. Recondition or replace the cylinder head, including intake and exhaust valves, guides, and seats. Replace the turbocharger if shaft play or oil leakage is detected. Ensure all gaskets and seals are replaced during reassembly to maintain compression and prevent fluid leaks.
Seasonal & Environment Servicing
In cold conditions, verify coolant concentration and battery capacity, as the mechanical engine lacks electronic cold-start assist beyond glow plugs. Use appropriate viscosity engine oil for ambient temperatures. In hot, dusty environments, shorten air cleaner service intervals and keep the radiator core clear of debris to prevent overheating. Inspect hydraulic hoses for cracking due to UV exposure. Check track tension and undercarriage wear more frequently in abrasive conditions. Ensure DEF levels are adequate for Tier 4 compliant variants if applicable.
S6D125-1M(S/N 11574-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 07281-00197 | Clamp,(With Pre-Fuel Filter) | Fuel system service | Check fitment → |
| 600-311-8291 | Cartridge,Fuel Filter | Fuel system service | Check fitment → |
| 600-311-9100 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| 6138-71-6100 | Fuel Filter Ass'Y,(See Fig.0419) | Fuel system service | Check fitment → |
| (600-311-9100) | Fuel Filter Ass'Y,Additional (See Fig.0418) | Fuel system service | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
S6D125-1M(S/N 11574-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor and backup speed sensor failure | Faulty speed sensor, broken wiring harness, or corroded connector at the pin connector | Replace the speed sensor and verify voltage at the pin connector |
| CA111 | Internal engine controller fault (ECM critical internal failure) | Malfunction within the Electronic Control Module (ECM) | Replace or reprogram the ECM |
| CA451 | Common rail pressure sensor feedback value too high | Malfunction in the rail pressure sensor or actual overpressure condition | Diagnose the fuel rail pressure sensor or check pump lines |
| CA452 | Common rail pressure sensor feedback value too low | Fuel rail pressure sensor error or low pressure condition | Diagnose the fuel rail pressure sensor or check pump lines |
| CA122 | Intake air pressure sensor feedback voltage too high | Faulty intake pressure sensor or wiring issue | Verify the intake pressure sensor and wiring |
| CA123 | Intake air pressure sensor feedback voltage too low | Sensor short or airflow restriction | Check for a sensor short or an airflow restriction |
| CA153 | Intake air temperature sensor feedback voltage too high | Faulty Intake Air Temperature (IAT) sensor | Replace or test the IAT sensor |
| CA154 | Intake air temperature sensor feedback voltage too low | Faulty Intake Air Temperature (IAT) sensor | Replace or test the IAT sensor |
| CA441 | Battery voltage too low | Weak battery, failing alternator, or voltage regulator issue | Replace the alternator or battery; check the voltage regulator |
| CA442 | Battery voltage too high | Failing alternator or voltage regulator | Replace the alternator or battery; check the voltage regulator |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
S6D125-1M(S/N 11574-UP) attachments & work tools
Bulldozer Blade Systems
The S6D125-1 engine powers the D65E-12, D65P-12, D65EX-12, and D65PX-12 dozer series, which utilize standard straight, semi-U, or full-U blades. Factory specifications for the D65-12 series list track gauge options of 1,880 mm (74 in) or 2,050 mm (81 in) and track shoe widths of 510 mm (20 in) or 950 mm (37 in). ROPS cab configurations add approximately 35 mm (1.4 in) to the overall height compared to canopy installations.
Excavator Work Tools
Machines equipped with this engine, such as the PC400-7 and PC400LC-8 excavators, support standard digging buckets, trenching buckets, and heavy-duty rock buckets. Attachment compatibility is determined by the specific hydraulic circuit arrangement of the host machine rather than the engine alone. Bucket capacities vary by configuration and series to match the machine's rated operating load.
Wheel Loader Attachments
The S6D125-1 and related 125 series engines are used in WA470-3 and WA480-5 wheel loaders, which are fitted with standard general-purpose, light material, or heavy-duty buckets. The mounting system relies on the loader's lift arm geometry and pin-on coupler interface. Hydraulic flow requirements for auxiliary circuits must be verified against the specific loader model's pump arrangement.
Hydraulic & Cooling Configurations
The engine is turbocharged and aftercooled, requiring specific radiator core maintenance to prevent debris blockage in dusty environments. Wet cylinder liners are used in direct contact with the coolant, necessitating the use of supplemental coolant additive to prevent cavitation pitting. Fluid specifications include Komatsu EO diesel engine oil, TO powertrain oil, and AF-NAC super coolant.
All S6D125-1M(S/N 11574-UP) assemblies by section
Every catalogued assembly group for the Komatsu S6D125-1M(S/N 11574-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Accessory
Komatsu : S6d125-1m(S/N 11574-Up) : Accessory : Air Compressor And Piping
| 01***20 | Bolt,(For Quick Shift) (Mitsubishi) | 1 |
| 01***40 | Bolt, Mount Master Brake Cylinder | 1 |
| 01***16 | Washer,Radio Controlled Slag Handling | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Accessory : Air Compressor(#11574-41217)
Komatsu : S6d125-1m(S/N 11574-Up) : Accessory : Air Compressor(#41218-)
| 61***11 | Air Compressor Ass'Y,(See Fig.0711a) | 1 |
| 61***12 | Air Compressor Ass'Y,(See Fig.0711a) | 1 |
| DK***20 | Connecting Rod A | 1 |
Cooling System
Komatsu : S6d125-1m(S/N 11574-Up) : Cooling System : Cooling Fan And Mounting
| 01***30 | Bolt,(For Quick Shift) (Mitsubishi) | 22 |
| 01***40 | Bolt, Mount Master Brake Cylinder | 2 |
| 01***15 | Bolt,(With Air Conditioner Type) | 4 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cooling System : Corrosion Resistor And Piping
| 01***20 | Bolt,(For Quick Shift) (Mitsubishi) | 1 |
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 4 |
| 01***08 | Nut,(For Canvas Canopy?Head Guard) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cooling System : Water Pump And Mounting
| 01***30 | Bolt,(For France Noise Suppression) | 2 |
| 01***16 | Bolt (With Air Heater & Conditioner) | 6 |
| 01***30 | Bolt,(For Quick Shift) (Mitsubishi) | 6 |
Cylinder Block
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Camshaft
| 01***22 | Bolt | 2 |
| 04***25 | Key, Plain Woodruff | 1 |
| 04***12 | Ring,Snap (For Ripper) | 12 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Crankshaft
| 01***25 | Bolt,(Without Rops Guard? Canopy) | 6 |
| 01***30 | Screw | 1 |
| 01***35 | Screw | 5 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Cylinder Block
| 01***12 | Bolt,(Without Air Compressor Type) | 2 |
| 01***45 | Washer,(For Travel Motor) (Not Show) | 14 |
| 04***14 | Pin, Dowel | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Cylinder Block (Cold Terrain Spec.) (Except Japan)
| 01***16 | Bolt, Battery To Frame Ground Wire Attaching | 1 |
| 01***12 | Bolt,(Without Air Compressor Type) | 2 |
| 01***16 | Washer,Radio Controlled Slag Handling | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Cylinder Block Cover
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 2 |
| 01***08 | Nut,(For Canvas Canopy?Head Guard) | 2 |
| 01***16 | Washer,Radio Controlled Slag Handling | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Flywheel And Flywheel Housing
| 01***50 | Bolt, Radiator To Frame | 6 |
| 01***60 | Bolt, Hanger Bearing Mounting | 2 |
| 01***45 | Bolt,(For Power Tilt Mech Angle) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Front Cover And Gear
| 01***25 | Bolt,(Without Auto Priming System) | 6 |
| 01***30 | Bolt,(For France Noise Suppression) | 6 |
| 01***60 | Screw | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Oil Pan
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 25 |
| 01***30 | Bolt,(For Quick Shift) (Mitsubishi) | 11 |
| 01***35 | Bolt,(For Quick Shift) (Mitsubishi) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Oil Pan (Extreme Cold Terrain Spec.) (Except Japan)
| 01***16 | Bolt (With Air Heater & Conditioner) | 1 |
| 01***16 | Bolt, Battery To Frame Ground Wire Attaching | 1 |
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 25 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Block : Piston And Connecting Rod
| 02***13 | Pin, Dowel | 2 |
| 04***18 | Ring, Snap | 12 |
| 61***31 | Piston Ring Ass'Y | 6 |
Cylinder Head
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Air Cleaner And Mounting
| 01***40 | Bolt,(Dust And Dirt Protection) | 2 |
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 4 |
| 01***50 | Bolt,(With Service Valve R.H.) | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Air Cleaner And Mounting (With Weather Cap)
| 01***40 | Bolt,(Dust And Dirt Protection) | 2 |
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 4 |
| 01***50 | Bolt,(With Service Valve R.H.) | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Air Intake Manifold And Connection
| 01***10 | Bolt,(With Auto Emergency Steering) | 2 |
| 01***30 | Bolt,(For Quick Shift) (Mitsubishi) | 13 |
| 01***40 | Bolt, Mount Master Brake Cylinder | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Cylinder Head(#11574-26760)
| 04***20 | Pin,Dowel (Welded) | 2 |
| 61***30 | Sleeve,Holder | 1 |
| 61***20 | Cotter, Valve | 48 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Cylinder Head(#26761-)
| 04***20 | Pin,Dowel (Welded) | 2 |
| 61***30 | Sleeve,Holder | 1 |
| 61***20 | Cotter, Valve | 48 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Exhaust Manifold And Turbocharger
| 01***00 | Bolt (M10-1.50x100) | 18 |
| 01***45 | Screw | 4 |
| 07***08 | Plug,(Without Auto Priming System) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Muffler And Mounting
| 01***40 | Bolt,(Dust And Dirt Protection) | 4 |
| 01***20 | Bolt,(For Quick Shift) (Mitsubishi) | 1 |
| 01***30 | Bolt,(For Quick Shift) (Mitsubishi) | 4 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Rocker Arm And Housing
| 01***95 | Bolt,(For 2nd Travel Speed) (Op) | 2 |
| 01***08 | Nut,R.H. Thread | 12 |
| 01***16 | Washer,Radio Controlled Slag Handling | 42 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Rocker Arm Housing Cover
| 01***16 | Washer,Radio Controlled Slag Handling | 24 |
| 61***10 | Cover,Head? No.2?3?4?5?6 | 6 |
| 61***11 | Cover,Head? No.2?3?4?5?6 | 6 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Turbocharger (Except Japan)(#11574-23903)
| 61***00 | Turbocharger Ass'Y,(See Fig.0155) | 1 |
| 61***00 | Turbocharger Ass'Y,(Tv7705) | 1 |
| GA***85 | V-Band Ass'Y | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Turbocharger (Except Japan)(#23904-)
| 61***10 | Turbocharger Ass'Y,(Ta4532) | 1 |
| GA***60 | V-Band | 1 |
| GA***52 | Center Housing A | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Water Manifold And Thermostat(#11574-14646)
| 02***43 | O-Ring,Water Manifold | 10 |
| 07***12 | Washer, Gasket,(Without Thermo Sensor) (K1) | 1 |
| 07***15 | Plug,(Used When Without Heater) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Cylinder Head : Water Manifold And Thermostat(#14647-)
| 02***43 | O-Ring,Water Manifold | 6 |
| 07***12 | Washer, Gasket,(Without Thermo Sensor) (K1) | 1 |
| 07***15 | Plug,(Used When Without Heater) | 1 |
Electrical System
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Alternator (25a) (With Hardening Pulley)
| 60***40 | Alternator A. (25a),(With Hardening Pulley) | 1 |
| 60***20 | Alternator A. (25a),(With Hardening Pulley) | 1 |
| KD***57 | Bearing,Ball? Front | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Alternator (35a) (With Hardening Pulley)(#16547-)
| 60***20 | Alternator A. (35a),(With Hardening Pulley) | 1 |
| KD***80 | Collar | 1 |
| KD***70 | Rear Bracket Ass'Y,Rear | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Alternator (35a)(#11574-16546)
| 60***20 | Alternator A. (35a),(With Hardening Pulley) | 1 |
| 60***60 | Alternator A. (35a),(With Non Hardening Pulley) | 1 |
| KD***57 | Bearing,Ball? Front | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Alternator (50a)(#11574-16546)
| 60***30 | Alternator A. (50a),(With Non Hardening Pulley) | 1 |
| 60***60 | Alternator A. (50a),(With Hardening Pulley) | 1 |
| SD***X0 | Pulley,Non Hardening | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Alternator (50a)(#16547-)
| 60***70 | Alternator A. (50a),(With Hardening Pulley) | 1 |
| 60***80 | Alternator A. (50a),(With Non Hardening Pulley) | 1 |
| SD***X0 | Washer | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Alternator And Mounting (25a? 35a? 50a)
| 01***30 | Bolt,(For Quick Shift) (Mitsubishi) | 1 |
| 01***35 | Bolt,(For Quick Shift) (Mitsubishi) | 1 |
| 01***30 | Bolt | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Solenoid Reray(#11574-28162)
| 17***20 | Relay,Engine Stop Solenoid | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Starting Motor (11kw)(#11574-20299)
| 60***30 | Starting Motor Ass'Y,(11kw)(See Fig.0662) | 1 |
| SD***09 | Metal | 1 |
| SD***60 | O-Ring | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Starting Motor (11kw)(#20300-35326)
| 60***20 | Starting Motor Ass'Y,(11kw)(See Fig.0662a) | 1 |
| 60***21 | Starting Motor Ass'Y,(11kw)(See Fig.0662a) | 1 |
| SD***X0 | Bar Ass'Y | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Starting Motor (11kw)(#35327-)
| 60***22 | Starting Motor Ass'Y,(11kw) | 1 |
| SD***X9 | Switch Ass'Y,Engage | 1 |
| SD***X0 | Bearing,Ball | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Starting Motor (7.5kw)(#11574-17373)
| 60***80 | Starting Motor Ass'Y,(7.5kw) | 1 |
| KD***20 | Magnetic Switch Assembly | 1 |
| KD***40 | Spring,Spring | 4 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Starting Motor (7.5kw)(#17374-)
| 60***80 | Starting Motor Ass'Y,(7.5kw) | 1 |
| KD***60 | Shift Lever Assembly | 1 |
| KD***40 | Spring,Spring | 4 |
Komatsu : S6d125-1m(S/N 11574-Up) : Electrical System : Starting Motor And Mounting (7.5kw? 11kw)
| 01***16 | Bolt, Battery To Frame Ground Wire Attaching | 1 |
| 01***40 | Bolt,(With Center Guard) | 3 |
| 08***19 | Band,(Without Air Conditioner) | 1 |
Engine Kit
Komatsu : S6d125-1m(S/N 11574-Up) : Engine Kit : Gasket Kit
| 02***43 | O-Ring,Water Manifold | 10 |
| 07***20 | O-Ring,Relief Valve | 1 |
| 07***15 | O-Ring,(For Low Speed) (D40pf) | 1 |
Fuel System
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Additionl Fuel Filer (Except Japan)
| 07***12 | Gasket,Mechanical Pump Piping | 2 |
| 60***91 | Cartridge,Fuel Filter | 1 |
| 60***00 | Fuel Filter Ass'Y | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Engine Stop Motor And Mounting (Key Stop Type)(#23904-)
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Fuel Filter And Piping
| 01***75 | Bolt,(For Adjusting) | 2 |
| 01***16 | Washer,Radio Controlled Slag Handling | 2 |
| 07***12 | Gasket,Mechanical Pump Piping | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Fuel Injection Pump (Coupling)
| 61***10 | Injection Pump A.,(See Fig.0451) | 1 |
| 61***12 | Injection Pump A.,(See Fig.0451) | 1 |
| 61***13 | Injection Pump A.,(See Fig.0451) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Fuel Injection Pump (Feed Pump)
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Fuel Injection Pump (Governor) (1/2)
| 61***10 | Injection Pump A.,(See Fig.0451) | 1 |
| 61***12 | Injection Pump A.,(See Fig.0451) | 1 |
| 61***13 | Injection Pump A.,(See Fig.0451) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Fuel Injection Pump (Governor) (2/2)
| 61***10 | Injection Pump A.,(See Fig.0451) | 1 |
| 61***12 | Injection Pump A.,(See Fig.0451) | 1 |
| 61***13 | Injection Pump A.,(See Fig.0451) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Fuel Injection Pump (Pump)
| 61***10 | Injection Pump A.,(See Fig.0451) | 1 |
| 61***12 | Injection Pump A.,(See Fig.0451) | 1 |
| 61***13 | Injection Pump A.,(See Fig.0451) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Fuel Injection Pump And Piping
| 01***30 | Bolt | 4 |
| 01***45 | Bolt,(For Power Tilt Mech Angle) | 2 |
| 01***55 | Bolt, Mount Tube To Switch Pump | 4 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Fuel Nozzle And Spill Pipe
| 01***45 | Bolt, Divider Valve Mounting | 12 |
| 07***65 | O-Ring,Cylinder Block | 6 |
| 07***12 | Gasket,Mechanical Pump Piping | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Solenoid And Mounting (Key Stop Type)(#11574-15804)
| 01***16 | Bolt,(For Slag Handling) | 2 |
| 01***20 | Bolt,(Without Maintenance Monitor) | 4 |
| 01***16 | Bolt, Battery To Frame Ground Wire Attaching | 3 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Solenoid And Mounting (Key Stop Type)(#15805-23903)
| 01***20 | Bolt,(Without Maintenance Monitor) | 4 |
| 01***65 | Bolt,(Except Japan) | 2 |
| 01***90 | Bolt, Fan Mounting | 2 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Water Separator And Piping (With Additional Fuel Filter) (Except Japan)
| 01***30 | Bolt,(For France Noise Suppression) | 4 |
| 01***35 | Bolt, Mounting - Flywheel Housing End | 6 |
| 07***12 | Gasket,Mechanical Pump Piping | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Fuel System : Water Separator And Piping (Without Additional Fuel Filter) (Except Japan)
| 01***30 | Bolt,(For Quick Shift) (Mitsubishi) | 2 |
| 01***35 | Bolt,(For Quick Shift) (Mitsubishi) | 2 |
| 01***55 | Bolt | 1 |
Lubricating Oil System
Komatsu : S6d125-1m(S/N 11574-Up) : Lubricating Oil System : Lubricating Oil Cooler
| 01***25 | Bolt,Without Revolution Sensor | 2 |
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 12 |
| 01***30 | Bolt,(For Quick Shift) (Mitsubishi) | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Lubricating Oil System : Lubricating Oil Filter And Mounting
| 01***25 | Bolt,(For Canvas Canopy?Head Guard) | 8 |
| 02***16 | Plug | 1 |
| 04***12 | Ring, Snap | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Lubricating Oil System : Lubricating Oil Piping(#11574-13430)
| 01***50 | Bolt,(With Service Valve R.H.) | 2 |
| 01***55 | Bolt, Mount Tube To Switch Pump | 2 |
| 01***16 | Washer,Radio Controlled Slag Handling | 7 |
Komatsu : S6d125-1m(S/N 11574-Up) : Lubricating Oil System : Lubricating Oil Piping(#13431-)
| 01***50 | Bolt,(With Service Valve R.H.) | 4 |
| 01***16 | Washer,Radio Controlled Slag Handling | 7 |
| 04***12 | Ring, Snap | 1 |
Komatsu : S6d125-1m(S/N 11574-Up) : Lubricating Oil System : Lubricating Oil Pump And Suction Pipe
| 01***25 | Bolt,(Without Auto Priming System) | 4 |
| 01***20 | Bolt,(Large Capacity Type) (Std) | 2 |
| 01***25 | Bolt,(Sandy? Dusty Terrain Spec.) | 5 |
Komatsu : S6d125-1m(S/N 11574-Up) : Lubricating Oil System : Turbocharger Lubricating Oil Piping
| 01***20 | Bolt,(With Auto Emergency Steering) | 2 |
| 01***30 | Bolt,(For Mechanical Governor) | 2 |
| 01***16 | Bolt, Battery To Frame Ground Wire Attaching | 2 |
S6D125-1M(S/N 11574-UP) serial number reference
The engine serial number plate is located on the left side of the engine block, near the injection pump. The plate displays the engine model (e.g., S6D125-1M) and the serial number; match the serial number to the 11574-UP range to confirm the correct parts catalog. The machine's chassis PIN plate is typically riveted to the right-hand side of the cab on the lower frame.
| Prefix | Identifies | Notes |
|---|---|---|
| S6D125-1M | Engine model | Identifies the S6D125-1M engine family. Serial range 11574-UP is explicitly listed in the Komatsu Parts Catalog for this engine variant. The 'M' suffix typically denotes a specific market or emissions configuration variant within the S6D125 series. No further 3-character PIN prefixes are documented for this specific engine serial range in the provided sources; verify with your dealer for specific machine build codes. |
Frequently asked questions
What is the engine type?
The Komatsu S6D125-1M is a turbocharged, aftercooled, six-cylinder, water-cooled, direct-injection diesel engine from the Komatsu 125 series.
What is the operating weight of the host machines?
Operating weight varies by configuration and series; for the D65E-12/D65P-12/D65EX-12/D65PX-12 dozers, it ranges from approximately 31,600 mm (103,675 lb) to 34,500 mm (113,190 lb) depending on ROPS/canopy and track shoe width.
What replaced the S6D125-1M?
The S6D125-1M was succeeded by the S6D125E-2 series engine, which was designed to meet stricter emissions standards while maintaining the 125 series platform.
What S6D125-1M(S/N 11574-UP) owners discuss
What are the typical power and torque specifications for the Komatsu S6D125-1 engine?
What are the known hydraulic behaviors and common failure patterns for Komatsu excavators equipped with this engine series?
What undercarriage and wear patterns are typical for machines using this engine type?
What are the specific engine quirks and maintenance requirements for the S6D125-1 series?
What are the common electrical and sensor issues reported for this engine platform?
What fluids and specifications are recommended for this engine and its associated systems?
What should be checked when buying a used machine with the S6D125-1 engine (S/N 11574-UP)?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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