Komatsuengine(no series)

Komatsu S6D125-1VV-R(S/N 35323-UP)

Maintenance schedule, common problems & OEM parts breakdown

Search live S6D125-1VV-R(S/N 35323-UP) parts

The Komatsu S6D125-1VV-R engine (S/N 35323-UP) is a turbocharged, aftercooled diesel powerplant designed for the PC400-5, PC400LC-5, and PC400HD-5K crawler excavator series. These machines belong to the 40-ton class, with operating weights typically ranging from 39,000 to 41,000 lb (17,700 to 18,600 kg) depending on the specific undercarriage and boom configuration. Production for this engine serial range corresponds to the PC400-5 generation, which succeeded the PC400-4 series and was eventually replaced by the PC400-6 and PC400LC-6 models. The S6D125-1VV-R configuration was standard for these mid-90s to early-2000s excavators, offering a balance of high torque and fuel efficiency for heavy digging and demolition applications.

Across the S6D125 engine lineage, the primary changes involved emissions compliance updates and minor internal component revisions to meet evolving Tier standards, while maintaining the core 6-cylinder architecture. The S6D125-1VV-R remains significant in the used and parts market because it powers the highly durable PC400-5 series, a workhorse in the secondary market. Its widespread use means parts availability is robust, and its mechanical simplicity compared to newer electronic-heavy engines makes it a preferred candidate for rebuilds and long-term fleet maintenance. The engine's reputation for longevity ensures continued demand for overhaul kits and specific wear components.

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 S6D125-1VV-R(S/N 35323-UP) specifications

Engine

Model	S6D125-1VV-R
Series/Generation	S6D125-1 (125 Series)
Type	4-stroke, water-cooled, direct injection diesel engine
Displacement	11.04 L (674 cu in)
Cylinders	6
Bore x Stroke	125 mm x 150 mm (4.92 in x 5.91 in)
Compression Ratio	17:1
Aspiration	Turbocharged and aftercooled
Gross Power	varies by configuration/series (typically 260 hp to 300 hp / 194 kW to 224 kW)
Net Power	varies by configuration/series (typically 260 hp to 300 hp / 194 kW to 224 kW)
Gross Torque	varies by configuration/series (typically 920 Nm to 1100 Nm / 678 lb-ft to 811 lb-ft)
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	Not documented for this exact serial range — verify with your dealer
Ground Clearance	Not documented for this exact serial range — verify with your dealer

Performance

Travel Speed	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 S6D125-1VV-R(S/N 35323-UP) maintenance schedule

Service interval	Tasks
Every 10 h	Check engine oil level. Check hydraulic fluid level. Check coolant level and secure cap. Drain water from fuel separator. Check DEF level. Check air filter restriction indicator.
Every 250 h	Change engine oil and filter. Grease all points. Check fluid levels. Check air filter. Inspect belts and hoses. Perform visual walk-around.
Every 500 h	Replace fuel filter. Replace hydraulic return filter. Service battery. Test coolant SCA. Collect KOWA oil sample. Inspect undercarriage.
Every 1,000 h	Collect hydraulic oil sample. Change final drive oil. Inspect turbocharger. Check valve adjustment. Inspect structural components. Measure undercarriage wear.
Every 2,000 h	Change hydraulic oil. Flush and replace coolant. Service transmission. Evaluate components comprehensively. Check KDPF. Replace worn belts and hoses.

Servicing the S6D125-1VV-R(S/N 35323-UP) beyond the schedule

Predictive Maintenance & Fluid Analysis

Utilize Komatsu KOWA fluid analysis at every 500-hour interval to monitor engine oil wear metals (iron, copper, lead) and contaminants. Check coolant SCA concentration at 500 hours to prevent liner cavitation in the S6D125-1VV-R block. Monitor hydraulic oil particle count and viscosity to protect the PC400-5's high-pressure pumps. Track DEF levels daily to ensure SCR system efficiency. Analyze final drive oil for gear wear indicators. Use KOMTRAX telematics to track load frequency and fuel consumption trends, identifying inefficiencies before they cause component failure.

Corrective & Common Repairs

Address oil leaks from the S6D125-1VV-R breather or valve cover gaskets by inspecting crankcase ventilation and seal integrity. Replace worn piston rings if excessive blow-by or oil consumption is detected, a known issue in high-hour units. Fix coolant contamination by replacing the cylinder head gasket or addressing cracked liners. Repair fuel injection pump issues by checking TVC settings and injector lines. Replace worn turbocharger bearings if boost pressure drops or excessive smoke occurs. Fix hydraulic hose cracks and leaks to maintain PC400-5 digging force and swing speed.

Overhaul & Rebuild Points

Perform an in-frame overhaul when compression drops below specification or oil consumption exceeds limits. Replace pistons, rings, and liners as a matched set to ensure proper clearance in the S6D125-1VV-R block. Inspect the crankshaft for journal wear and replace if out of tolerance. Rebuild the fuel injection pump and replace all injectors to restore proper spray patterns. Replace the turbocharger if shaft play is excessive. Rebuild the hydraulic pump and swing motor if flow rates drop below factory specs for the PC400-5.

Seasonal & Environment Servicing

In cold weather, use lower viscosity engine oil and ensure the coolant mixture provides adequate freeze protection for the S6D125-1VV-R. Pre-heat the engine block and oil pan before starting in extreme cold. In dusty environments, check the air filter restriction indicator more frequently and clean the radiator and oil cooler fins daily to prevent overheating. In high-humidity areas, drain the fuel water separator daily to prevent microbial growth. Inspect the undercarriage and tracks for mud buildup and wear after wet or muddy operations to maintain PC400-5 stability and traction.

S6D125-1VV-R(S/N 35323-UP) common service parts

Part number	Part	Notes
07281-00197	Clamp,(With Pre-Fuel Filter)	Fuel system service	Check fitment →
600-311-8282	Cartridge,Fuel Filter	Fuel system service	Check fitment →
6114-71-6201	Fuel Filter Ass'Y	Fuel system service	Check fitment →
6114-71-6210	Head, Fuel Filter	Fuel system service	Check fitment →
6151-71-6601	Fuel Filter Ass'Y,(B)	Fuel system service	Check fitment →

Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.

S6D125-1VV-R(S/N 35323-UP) fault codes & troubleshooting

Code	Meaning	Likely cause	What to do
CA115	Engine crankshaft speed sensor failure	Faulty crankshaft speed sensor, broken wiring harness, or corroded pin connector	Replace the speed sensor and verify voltage at the pin connector
CA451	Common rail pressure sensor feedback value too high	Malfunctioning rail pressure sensor or actual overpressure condition	Diagnose the fuel rail pressure sensor or check pump lines
CA111	Internal engine controller fault	Critical internal failure of the Electronic Control Module (ECM)	Replace or reprogram the ECM
CA234	Engine overspeed	Throttle calibration error, engine load cycle issue, or operator misuse	Verify throttle calibration and engine load cycle
CA441	Battery voltage too low	Weak battery, failing alternator, or loose connections	Replace the alternator or battery; check the voltage regulator
CA122	Intake air pressure high voltage	Faulty intake pressure sensor or restricted airflow	Verify the intake pressure sensor and wiring
CA153	Intake air temperature sensor high error	Faulty intake air temperature (IAT) sensor	Replace or test the IAT sensor
CA2311	IMV solenoid valve failure	Faulty Inlet Manifold Valve (IMV) solenoid or wiring harness issue	Replace the IMV solenoid or inspect the wire harness
AA10NX	Air cleaner clogging	Clogged air filter element	Replace the air filter
B@BCNS	Engine coolant overheating	Low coolant level, failed fan belt, or blocked radiator fins	Check 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.

S6D125-1VV-R(S/N 35323-UP) attachments & work tools

Excavator Attachments

The S6D125-1VV-R engine (S/N 35323-UP) powers the PC400-5 series, including the PC400-5, PC400LC-5, and PC400HD-5K. Factory configurations for this class typically include bucket capacities ranging from 1.5 to 2.5 cubic meters, depending on the specific sub-model and ground conditions. Coupler systems vary by configuration, with standard quick couplers or fixed pin setups available for hydraulic breakers and grapples.

Wheel Loader Attachments

This engine is installed in the WA470-3 and WA470-5 wheel loader series. Typical work tools include buckets with capacities between 2.0 and 3.0 cubic meters, optimized for the machine's class. Hydraulic arrangements for auxiliary tools like grapples or mulchers require specific flow and pressure kits compatible with the loader's hydraulic system.

Dozer Attachments

The S6D125-1VV-R engine is listed for the D65E-12 and D65PX-12 dozer series. Standard work tools include straight blades and angle blades, with capacities varying by configuration and series. Factory guarding options often include heavy-duty side cutters and root rakes for land-clearing applications.

Motor Grader Attachments

The engine is compatible with the GD663A-2 motor grader. Typical work tools include moldboard blades with widths around 3.6 to 4.0 meters, depending on the specific configuration. Auxiliary options may include side shift mechanisms and angle adjustments for precise grading operations.

All S6D125-1VV-R(S/N 35323-UP) assemblies by section

Every catalogued assembly group for the Komatsu S6D125-1VV-R(S/N 35323-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Cooling System

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cooling System : Cooling Fan And Mounting

01***30	Bolt,(For Quick Shift) (Mitsubishi)	22
01***15	Bolt,(With Air Conditioner Type)	6
01***14	Nut,(For Slag Handling)	1
01***16	Washer,(With Water Separator)	4

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cooling System : Corrosion Resistor And Piping

01***25	Bolt,(For Canvas Canopy?Head Guard)	4
02***25	Bolt,(Cold Weather Spec.)	4
07***32	Hose,(See Fig.0411-11)	1
07***56	Hose, Flexible	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-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)	3
01***35	Bolt,(For Quick Shift) (Mitsubishi)	3

See all parts with full part numbers in Heavy Parts AI →

Cylinder Block

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Block : Camshaft

01***22	Bolt	2
04***25	Key, Plain Woodruff	1
04***12	Ring,Snap (For Ripper)	12
61***12	Camshaft Assembly	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Block : Crankshaft

01***25	Bolt,(Without Rops Guard? Canopy)	6
01***30	Screw	1
01***35	Screw	5
04***28	Pin, Dowel - Transmission Case, Pin-Dowel	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-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
04***20	Pin,Dowel (Welded)	12

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Block : Cylinder Block Cover (B Spec.) (Except Japan)(#47234-)

01***20	Bolt,(For Quick Shift) (Mitsubishi)	2
01***30	Bolt,(For Quick Shift) (Mitsubishi)	1
01***08	Nut,(For Canvas Canopy?Head Guard)	2
01***16	Washer,Radio Controlled Slag Handling	3

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Block : Flywheel And Flywheel Housing (B Spec.) (Except Japan)(#47234-)

01***50	Bolt	2
01***50	Bolt, Radiator To Frame	6
01***60	Bolt, Hanger Bearing Mounting	2
01***45	Screw	6

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Block : Front Cover And Gear

01***30	Bolt,(For France Noise Suppression)	6
01***60	Screw	1
01***65	Bolt,(Except Japan)	6
01***70	Bolt, Mount Bracket And Oil Inlet Tube, Bolt	4

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Block : Oil Pan (B Spec.) (Except Japan)(#47234-)

01***12	Bolt, Bolt,(No Need To Quick Shift)	3
01***25	Bolt,(For Canvas Canopy?Head Guard)	28
01***30	Bolt,(For Quick Shift) (Mitsubishi)	7
01***10	Washer	3

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Block : Piston And Connecting Rod

02***13	Pin, Dowel	2
04***18	Ring, Snap	12
61***32	Piston Ring Ass'Y	6
61***33	Piston Ring Ass'Y	6

See all parts with full part numbers in Heavy Parts AI →

Cylinder Head

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Air Cleaner And Mounting (B Spec.) (Except Japan)(#47234-)

01***25	Bolt,(For Canvas Canopy?Head Guard)	4
01***60	Bolt,(For Ripper)	2
01***00	Bolt, Mount Back-Up Alarm	2
01***16	Washer,Radio Controlled Slag Handling	4

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Air Cleaner And Mounting (B Spec.) (Except Japan)(#49864-)

01***25	Bolt,(For Canvas Canopy?Head Guard)	2
01***30	Bolt,(For Quick Shift) (Mitsubishi)	2
01***45	Bolt,(For Power Tilt Mech Angle)	2
01***60	Bolt,(For Ripper)	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Air Intake Manifold And Connection

01***10	Bolt,(With Auto Emergency Steering)	2
01***20	Bolt,(For Quick Shift) (Mitsubishi)	2
01***30	Bolt,(For Quick Shift) (Mitsubishi)	11
01***45	Bolt,(For Power Tilt Mech Angle)	3

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Cylinder Head(#35323-48087)

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Cylinder Head(#48088-)

04***20	Pin,Dowel (Welded)	2
61***30	Sleeve,Holder	1
61***20	Cotter, Valve	48
61***40	Seal,Exhaust Valve (K1)	12

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Exhaust Manifold And Turbocharger(#35323-48087)

01***55	Bolt,(For Suction? Reversible Fan)	2
01***00	Bolt (M10-1.50x100)	22
01***45	Screw	2
01***55	Bolt, Mount Dryer To Bracket And Frame	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Exhaust Manifold And Turbocharger(#48088-)

01***35	Bolt, M10x1.5x35	2
01***00	Bolt (M10-1.50x100)	18
01***45	Screw	2
07***08	Plug,(Without Auto Priming System)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Muffler And Mounting

01***20	Bolt,(For Quick Shift) (Mitsubishi)	4
01***25	Bolt,(For Canvas Canopy?Head Guard)	7
01***35	Bolt,(For Quick Shift) (Mitsubishi)	1
01***40	Bolt, Mount Master Brake Cylinder	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Rocker Arm And Housing

01***08	Nut,R.H. Thread	12
01***32	Washer,(With Auto Emergency Steering)	42
61***10	Housing, Rocker Lever	6
61***10	Gasket,Rocker Arm Housing	6

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Rocker Arm Housing Cover

01***16	Washer,Radio Controlled Slag Handling	24
07***50	Cap,Oil Filler	1
07***50	Cap,Filler	1
61***11	Cover,Head? No.2?3?4?5?6	5

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Turbocharger

61***10	Turbocharger Ass'Y,(Ta4532)	1
61***10	Turbocharger Ass'Y,(Ta4532)	1
GA***60	V-Band	1
GA***14	Housing,Compressor	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Cylinder Head : Water Manifold And Thermostat (B Spec.) (Except Japan)(#47234-)

02***43	O-Ring	6
07***08	Plug,(Without Auto Priming System)	1
07***15	Plug,(Used When Without Heater)	1
07***08	Plug,(Without Oil Pressure Switch)	1

See all parts with full part numbers in Heavy Parts AI →

Electrical System

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Electrical System : Alternator (35a) (B Spec.) (Except Japan)(#47234-)

60***70	Alternator A. (35a),(With Non Hardening Pulley)	1
KD***90	Rectifier Ass'Y	1
KD***80	Collar	1
KD***62	Screw	3

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Electrical System : Alternator (50a)

60***80	Alternator A. (50a),(With Non Hardening Pulley)	1
SD***X0	Pulley,Non Hardening	1
SD***X0	Washer	1
SD***X0	Fan	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Electrical System : Alternator And Mounting (25a? 35a? 50a)

01***75	Bolt,(For Adjusting)	1
01***30	Bolt	1
01***23	Washer,(A)(W/After Cooler)(S6d155-4b)	2
01***32	Washer,(Not Used With Emergency Str.)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Electrical System : Electrical Wiring (B Spec.) (Except Japan)(#47234-)

01***16	Bolt, Battery To Frame Ground Wire Attaching	1
01***20	Bolt,(For Quick Shift) (Mitsubishi)	1
01***12	Bolt,(See Fig.0501)	3
01***16	Bolt,(With Alternator Cover Type)	5

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Electrical System : Starting Motor (11kw) (B Spec.) (Except Japan)(#47234-)

60***20	Starting Motor Ass'Y,(11kw)	1
SD***X0	Bearing,Ball	1
SD***X0	Armature Ass'Y	1
SD***X0	Seal,Oil	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Electrical System : Starting Motor (7.5kw)

60***70	Starting Motor Ass'Y,(7.5kw)	1
KD***20	Magnetic Switch Assembly	1
KD***40	Spring,Spring	4
KD***30	Washer Ass'Y,(Not Shown)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Electrical System : Starting Motor And Mounting (7.5kw? 11kw)

01***40	Bolt,(With Center Guard)	3
66***10	Gasket,Starting Motor	1
(6***0)	Starting Motor Ass'Y,(11kw) (See Fig.A6210-B3e4)	1
(6***0)	Starting Motor Ass'Y,(7.5kw) (See Fig.A6210-B4a9)	1

See all parts with full part numbers in Heavy Parts AI →

Fuel System

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Fuel System : Fuel Filter And Piping

01***20	Bolt,(For Quick Shift) (Mitsubishi)	1
01***25	Bolt,(For Canvas Canopy?Head Guard)	1
01***30	Bolt,(For Quick Shift) (Mitsubishi)	2
01***08	Nut,(For Canvas Canopy?Head Guard)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Fuel System : Fuel Injection Pump (Coupling) (B Spec.) (Except Japan)(#47234-)

ND***10	Flange,Coupling	1
ND***50	Bolt	1
ND***40	Bolt	2
ND***61	Bolt	6

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Fuel System : Fuel Injection Pump (Feed Pump) (B Spec.) (Except Japan)(#47234-)

ND***40	Washer? 1mm,Plate	1
ND***10	Spring, Check Valve	2
ND***20	Pump Ass'Y,Priming Pump	1
ND***60	Spring,Piston	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Fuel System : Fuel Injection Pump (Governor) (1/2) (B Spec.) (Except Japan)(#47234-)

ND***40	Plate,Thrust	1
ND***40	Plug,Screw	1
ND***10	Adapter	1
ND***70	Governor Ass'Y	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Fuel System : Fuel Injection Pump (Governor) (2/2) (B Spec.) (Except Japan)(#47234-)

ND***80	Pin,Stop	1
ND***20	Washer? 1.0mm,Cover Plate	2
ND***80	Plate,Cover	1
ND***10	Washer? 1.6mm,Nipple	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Fuel System : Fuel Injection Pump (Pump) (1/2) (B Spec.) (Except Japan)(#47234-)

61***30	Injection Pump A	1
ND***50	Ring,Adjust	1
ND***20	Retainer,Bearing	1
ND***00	Bearing,Center	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Fuel System : Fuel Injection Pump And Piping

01***75	Bolt,(See Fig.0142)	4
01***30	Bolt	4
01***20	Bolt,(For Quick Shift) (Mitsubishi)	2
01***25	Bolt,(For Canvas Canopy?Head Guard)	4

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Fuel System : Fuel Nozzle And Spill Tube

01***45	Bolt, Divider Valve Mounting	12
07***65	O-Ring,Cylinder Block	6
07***12	Gasket,(Without Air Compressor Type) (K2)	12
07***09	Tube,Spill	2

See all parts with full part numbers in Heavy Parts AI →

Kit

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Kit : Gasket Kit

02***43	O-Ring,Water Manifold	6
07***15	O-Ring,(For Low Speed) (D40pf)	1
07***25	O-Ring,Injection Pump Mounting	1
07***15	O-Ring,Relief Valve	1

See all parts with full part numbers in Heavy Parts AI →

Lubricating Oil System

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Lubricating Oil System : Lubricating Oil Cooler

01***25	Bolt,(For Canvas Canopy?Head Guard)	12
01***30	Bolt,(For Quick Shift) (Mitsubishi)	1
01***65	Bolt,(Except Japan)	2
01***80	Bolt,(Not Shown)	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Lubricating Oil System : Lubricating Oil Filter And Mounting

01***25	Bolt,(For Canvas Canopy?Head Guard)	2
01***30	Bolt,(For Quick Shift) (Mitsubishi)	3
01***35	Bolt,(For Quick Shift) (Mitsubishi)	1
01***80	Bolt,(Not Shown)	4

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Lubricating Oil System : Lubricating Oil Piping

01***25	Bolt,(For Canvas Canopy?Head Guard)	1
01***50	Bolt,(With Service Valve R.H.)	4
01***70	Bolt, Mount Bracket And Oil Inlet Tube, Bolt	1
01***08	Nut,(For Canvas Canopy?Head Guard)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-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)	1
01***25	Bolt,(Sandy? Dusty Terrain Spec.)	4
01***35	Bolt, Mounting - Flywheel Housing End	2

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Lubricating Oil System : Turbocharger Lubricating Oil Piping(#35323-48087)

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
01***20	Bolt,(For Quick Shift) (Mitsubishi)	1

See all parts with full part numbers in Heavy Parts AI →

Komatsu : S6d125-1vv-R(S/N 35323-Up) : Lubricating Oil System : Turbocharger Lubricating Oil Piping(#48088-)

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
01***20	Bolt,(For Quick Shift) (Mitsubishi)	1

See all parts with full part numbers in Heavy Parts AI →

S6D125-1VV-R(S/N 35323-UP) serial number reference

Locate the engine data plate on the left side of the engine block or near the valve cover; the engine serial number is stamped on the block itself, typically near the injection pump. The prefix 'S6D125-1VV-R' is the engine model code, not a chassis PIN prefix; match the engine serial number (starting at 35323) on the plate to the catalog range to confirm fitment.

Prefix	Identifies	Notes
S6D125-1VV-R	Engine Model	Identifies the specific engine configuration (S6D125-1VV-R) fitted to the machine. The serial number range S/N 35323-UP is explicitly tied to this engine model in parts catalog listings and component compatibility guides. This engine is commonly associated with the PC400-5 / LC-5 / LC-5T excavator series and WA470-3 wheel loader series, though the engine prefix itself identifies the powerplant rather than the chassis family. Build years for this specific engine serial range are not documented in the provided sources; verify with your dealer for exact production dates.

Frequently asked questions

What engine does the Komatsu PC400-5 use?

The Komatsu PC400-5 excavator uses the S6D125-1VV-R engine for serial numbers 35323 and up.

What is the operating weight of a Komatsu PC400-5?

The operating weight of a Komatsu PC400-5 varies by configuration, typically ranging from 39,000 to 41,000 lb (17,700 to 18,600 kg).

What replaced the Komatsu PC400-5?

The Komatsu PC400-5 was replaced by the PC400-6 and PC400LC-6 models.

What S6D125-1VV-R(S/N 35323-UP) owners discuss

How does the S6D125-1VV-R engine's hydraulic pump setup differ from the L10 variant, and what is the community consensus on reliability?

The S6D125-1VV-R engine is paired with a hydraulic pump setup where the TVC (Travel Valve Control) is set to the midpoint between minimum and maximum. In contrast, L10 variants typically have the TVC set near the maximum. Community consensus indicates the S6D125-1VV-R is more suitable for Komatsu's advanced hydraulic systems than the Cummins L10, which was prone to valve train damage and piston ring issues around 4,000 hours. The S6D125-1VV-R is regarded as durable, often running until mechanical failure rather than wearing out, provided maintenance is consistent. Hardened liners matched to OEM rings are standard and prevent wear issues common in other brands.

What are the typical torque and power characteristics of the S6D125-1VV-R engine?

The S6D125-1VV-R is a turbocharged and aftercooled diesel engine. Torque output varies by configuration and application, generally ranging from 920 Nm (678 lb-ft) to 1100 Nm (811 lb-ft). The engine is known for high reliability and power density, making it suitable for heavy-duty applications like the PC400 series excavators and D65 dozers.

What are the common undercarriage and wear patterns associated with machines using this engine series?

Machines equipped with the S6D125-1VV-R, such as the PC400LC-5 and D65EX-12, are heavy-duty units subject to significant undercarriage wear. Typical wear patterns include track shoe elongation, sprocket tooth wear, and idler/seal failures due to high ground pressure and continuous load. Operators report that undercarriage life is heavily dependent on operating surface conditions; abrasive environments accelerate wear on pins, bushings, and rollers. Regular cleaning of track frames is critical to prevent debris-induced seal failure.

What electrical or sensor issues are commonly reported for this engine series?

Komatsu excavators with this engine series rely on electronic control systems that can trigger multiple warning signals from single faulty sensors or unstable power supplies. Common issues include intermittent starting, dashboard failures, and random shutdowns. Fault codes related to engine controller power failure (E10), engine control failure (E11), and sensor malfunctions (E15) are frequent. These often stem from wiring harness chafing or connector corrosion rather than internal engine faults.

What are the known coolant and oil system quirks for the S6D125-1VV-R?

A known issue is coolant contamination leading to water in the crankcase, particularly in older units. This can result from a failing head gasket or cracked liner. Additionally, oil leakage from the breather is a reported symptom, often traced back to piston ring wear or excessive crankcase pressure. Operators should monitor oil levels closely and inspect the breather line for blockages or oil saturation.

What maintenance intervals and fluid specifications are standard for this engine?

Komatsu recommends daily checks and service intervals at 250, 500, 1000, 2000, and 4000 hours. Fluid specifications include Komatsu EO or equivalent diesel engine oil, Komatsu TO or equivalent hydraulic oil, and Komatsu Super Coolant AF-NAC. Fuel and oil filters should be replaced at 500-hour intervals, with more thorough services at 2000-hour marks. KOWA (Komatsu Oil Wear Analysis) is recommended at major intervals to monitor internal engine health.

What should be checked when buying a used machine with the S6D125-1VV-R engine (S/N 35323-UP)?

Verify the serial number matches the S/N 35323-UP range to ensure correct parts catalog alignment. Check for oil in the coolant or water in the crankcase, a known failure mode. Inspect the hydraulic pump TVC setting and look for signs of valve train damage if the machine was previously equipped with a Cummins L10 (though S/N 35323-UP units are S6D125-1VV-R). Test for intermittent electrical faults, dashboard errors, and random shutdowns. Inspect the undercarriage for excessive wear on track shoes, sprockets, and idlers. Ensure the turbocharger and aftercooler are free of leaks or blockages. Have your dealer verify the engine's compression and internal wear via KOWA analysis before purchase.

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

Need a specific S6D125-1VV-R(S/N 35323-UP) part?

Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.

Search parts in the app