Komatsuengine(no series)
Komatsu S6D105-1TT(S/N 86423-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu S6D105-1TT (S/N 86423-UP) is a turbocharged, six-cylinder diesel engine belonging to the 6D105 series family. It powers mid-size Komatsu wheel loaders such as the WA250-1LC and WA250-3, as well as various excavator and dozer models from the 1990s and early 2000s. This engine delivers approximately 170 horsepower and 550 lb-ft of torque, designed for heavy-duty construction and mining applications. The S6D105-1TT configuration is distinct from the naturally aspirated S6D105-1 and the later S6D105E-1 series, featuring specific turbo and fuel system components tailored for its era of production.
Across the 6D105 series generations, the primary changes involved the transition from mechanical fuel injection to electronic control systems in the E-series variants, along with updates to emissions compliance for Tier 2 and Tier 3 standards. The S6D105-1TT remains significant in the used and parts market due to its widespread installation in the durable WA250 wheel loader and PC200/PC220 excavator lines. Its mechanical simplicity compared to modern Tier 4 engines makes it a preferred choice for independent rebuilds and long-term fleet maintenance where electronic dependency is a liability.
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 S6D105-1TT(S/N 86423-UP) specifications
Engine
| Model | S6D105-1TT |
| Series | S6D105-1 |
| Displacement | 6.5 l (396 cu. inch) |
| Cylinders | 6 |
| Aspiration | Turbocharged |
| Fuel System | Direct injection, mechanical fuel system |
| Power | 170 hp (127 kW) |
| Torque | 550 lb-ft (745 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 | 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 |
| Dig Depth | Not documented for this exact serial range — verify with your dealer |
| Swing Speed | Not documented for this exact serial range — verify with your dealer |
Service capacities (summary)
| Engine Oil Refill Capacity | Varies by configuration/series (refer to engine model specific table in Operation and Maintenance Manual) |
| Cooling System Capacity | Not documented for this exact serial range — verify with your dealer |
| Fuel Tank Capacity | Not documented for this exact serial range — verify with your dealer |
| Hydraulic System Capacity | 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 S6D105-1TT(S/N 86423-UP) maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 4,000 h |
|
Servicing the S6D105-1TT(S/N 86423-UP) 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 levels at 500 hours to prevent cavitation in the S6D105-1TT cylinder liners. Monitor hydraulic oil particle count to protect the high-pressure pump. Track fuel dilution in the engine oil to detect injector or piston ring wear early. Use KOMTRAX telematics to correlate load frequency with fluid degradation rates for optimized change intervals.
Corrective & Common Repairs
Address intermittent starting issues by inspecting the starter motor and battery cables common in this serial range. Replace worn turbocharger seals if blue smoke appears under load. Fix hydraulic hose leaks promptly to prevent pump cavitation damage. Inspect the fuel injection pump for wear if power drops or fuel consumption rises. Check the air filter restriction indicator daily to prevent turbocharger damage from dust ingestion. Replace worn piston rings if compression drops below specification.
Overhaul & Rebuild Points
Plan an inframe overhaul around 10,000 to 12,000 hours for the S6D105-1TT. Replace pistons, rings, and liners during the overhaul to restore compression. Inspect the crankshaft for journal wear and replace if out of tolerance. Check the cylinder head for warpage and replace valves if seats are damaged. Rebuild the fuel injection pump and injectors to ensure proper spray pattern and pressure. Replace all gaskets and seals during disassembly to prevent leaks.
Seasonal & Environment Servicing
In cold climates, use lower viscosity engine oil and ensure the coolant mixture provides adequate freeze protection. Check the battery charge frequently in cold weather as capacity drops. In hot environments, clean the radiator and oil cooler fins daily to prevent overheating. Inspect the thermostat operation to ensure it opens at the correct temperature. Use high-temperature hydraulic fluid in extreme heat to maintain viscosity. Drain and clean the fuel water separator more frequently in humid conditions.
S6D105-1TT(S/N 86423-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 07281-00197 | Clamp,(With Pre-Fuel Filter) | Fuel system service | Check fitment → |
| 600-311-9100 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| 600-311-8221 | Cartridge,Engine Fuel Filter | Fuel system service | Check fitment → |
| 6136-71-6120 | Cartridge,Engine Fuel Filter | Fuel system service | Check fitment → |
| 6136-72-6100 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
S6D105-1TT(S/N 86423-UP) fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CA115 | Engine crankshaft speed sensor failure | Broken sensor, wiring issue, or connector corrosion | Replace the speed sensor and verify the voltage at the pin connector |
| CA111 | Internal engine controller fault | ECM internal abnormality | Replace or reprogram the ECM |
| CA441 | Battery voltage too low | Weak battery or charging system issue | Replace the battery or alternator; check the voltage regulator |
| CA442 | Battery voltage too high | Alternator overcharging or regulator failure | Replace the alternator or battery; check the voltage regulator |
| CA122 | Intake air pressure high voltage | Sensor malfunction or actual overpressure condition | Verify the intake pressure sensor and wiring |
| CA123 | Intake air pressure low voltage | Sensor short or airflow restriction | Check for a sensor short or an airflow restriction |
| CA451 | Common rail pressure sensor feedback value too high | Fuel rail sensor malfunction or actual overpressure | Diagnose the fuel rail pressure sensor or pump lines |
| CA234 | Engine overspeed | Throttle calibration error, engine load cycle issue, or operator misuse | Verify throttle calibration, engine load cycle, or operator misuse |
| CA153 | Intake air temperature sensor high error | Sensor failure or high intake temperature | Replace or test the IAT sensor |
| CA154 | Intake air temperature sensor low error | Sensor failure or low intake temperature | Replace or test the IAT sensor |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
S6D105-1TT(S/N 86423-UP) attachments & work tools
Bucket
Standard and heavy-duty buckets are the primary work tool for the WA250-1LC wheel loader equipped with this engine. Typical capacities for this class range from 2.0 to 3.0 cubic meters (2.6 to 3.9 cubic yards), varying by configuration/series based on material density and application requirements.
Pallet Forks
Hydraulic-operated pallet forks are a common attachment for material handling tasks. They mount to the standard loader linkage and utilize the machine's auxiliary hydraulic circuits for tilt and spread functions.
Quick Coupler
A hydraulic quick coupler system is typically installed to allow rapid tool changes. It connects to the loader's hydraulic lines to operate the locking mechanism, enabling the operator to switch between buckets and forks without leaving the cab.
Hydraulic Piping
Auxiliary hydraulic piping kits are required for attachments that need additional flow, such as pallet forks or specialized grapples. These kits route high-pressure lines from the main valve to the quick coupler or remote ports on the loader arms.
All S6D105-1TT(S/N 86423-UP) assemblies by section
Every catalogued assembly group for the Komatsu S6D105-1TT(S/N 86423-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Accessory
Komatsu : S6d105-1tt(S/N 86423-Up) : Accessory : Air Compressor
| 61***12 | Air Compressor Ass'Y | 1 |
| DK***00 | Cylinder | 1 |
| DK***90 | Washer,Air Compressor | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Accessory : Air Compressor And Piping
| 07***16 | Gasket,Air Compressor Piping | 1 |
| 07***89 | Clamp,(For Japan) | 2 |
| 61***30 | Elbow,(For Pc200) | 1 |
Cooling System
Komatsu : S6d105-1tt(S/N 86423-Up) : Cooling System : Corrosion Resistor And Piping
| 01***25 | Bolt,(Sandy? Dusty Terrain Spec.) | 4 |
| 01***20 | Bolt, Hose Clamps (Inlet And Return Line Hoses) | 4 |
| 01***29 | Washer,Spring (Cold Weather Spec.) | 4 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cooling System : Water Pump And Cooling Fan
| 01***16 | Bolt,(For Slag Handling) | 2 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 3 |
| 01***55 | Bolt,(For Suction? Reversible Fan) | 2 |
Cylinder Block
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Camshaft And Tappet
| 01***25 | Bolt,(Without Auto Priming System) | 2 |
| 01***20 | Bolt,(Forwarded Individually Parts) | 2 |
| 01***25 | Washer,Spring?(Sandy And Dusty Spec.) | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Crankshaft (With Air Conditioner)
| 01***70 | Bolt, Heater Hose Clip | 6 |
| 01***45 | Bolt,Nylock | 1 |
| 01***70 | Bolt,(For 75a Alternator) | 6 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Crankshaft (Without Air Conditioner)
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Cylinder Block
| 01***30 | Bolt,(For France Noise Suppression) | 3 |
| 01***45 | Bolt,(For Suction? Reversible Fan) | 1 |
| 01***20 | Bolt,(Used When Towing Winch) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Flywheel And Flywheel Housing(#86423-92027)
| 01***40 | Bolt,(Dust And Dirt Protection) | 9 |
| 01***45 | Bolt,(Cold Terrain Spec.) | 8 |
| 01***55 | Bolt,(For France Noise Suppression) | 4 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Flywheel And Flywheel Housing(#92028-)
| 01***35 | Bolt - Torque Converter Totransmission Mounting | 2 |
| 01***40 | Bolt,(Dust And Dirt Protection) | 9 |
| 01***45 | Bolt,(Cold Terrain Spec.) | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Front Cover And Gear
| 01***22 | Bolt,(Cold Terrain Spec.) | 4 |
| 01***25 | Bolt,(Without Auto Priming System) | 4 |
| 01***60 | Bolt,(Without Alternator Bracket) | 10 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Oil Pan (Cold Terrain Spec.) (With Oil Level Sensor)
| 01***22 | Bolt,(Cold Terrain Spec.) | 29 |
| 01***25 | Bolt,(Without Auto Priming System) | 8 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Oil Pan (Cold Terrain Spec.) (Without Oil Level Sensor)
| 01***22 | Bolt,(Cold Terrain Spec.) | 29 |
| 01***25 | Bolt,(Without Auto Priming System) | 8 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Oil Pan (With Oil Level Sensor)
| 01***22 | Bolt,(Cold Terrain Spec.) | 29 |
| 01***25 | Bolt,(Without Auto Priming System) | 8 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Oil Pan (Without Oil Level Sensor)
| 01***22 | Bolt,(Cold Terrain Spec.) | 29 |
| 01***25 | Bolt,(Without Auto Priming System) | 8 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Block : Piston And Connecting Rod
| 04***18 | Ring, Retaining | 2 |
| 61***40 | Crank Pin Metal A | 6 |
| 61***01 | Connecting Rod Ass'Y,(B) | 6 |
Cylinder Head
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Head : Air Cleaner And Mounting
| 01***25 | Bolt,(Sandy? Dusty Terrain Spec.) | 4 |
| 01***50 | Bolt | 2 |
| 01***55 | Bolt,(For Suction? Reversible Fan) | 4 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Head : Air Intake Manifold And Connection
| 01***16 | Bolt (Welded) | 2 |
| 01***20 | Bolt | 2 |
| 01***50 | Bolt,(For Trimming Dozer) | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Head : Cylinder Head
| 01***30 | Bolt,(For France Noise Suppression) | 2 |
| 01***25 | Bolt, Mount Engine Oil Drain To Fuel Tank | 2 |
| 01***30 | Washer,Spring(Sandy?Dusty Terrain S.) | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Head : Cylinder Head Cover
| 07***23 | Clamp - Hose | 1 |
| 07***00 | Clip | 1 |
| 07***30 | Clip | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Head : Exhaust Manifold And Turbocharger
| 01***60 | Bolt (M10-1.50x60) | 1 |
| 01***00 | Bolt (M10-1.50x100) | 9 |
| 01***15 | Bolt | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Head : Muffler And Mounting
| 01***40 | Bolt,(Dust And Dirt Protection) | 4 |
| 01***45 | Bolt,(For Suction? Reversible Fan) | 4 |
| 01***95 | Bolt,(For Reversible Fan) | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Head : Rocker Arm
| 01***80 | Bolt,(Shim 5 Pieces Over) | 2 |
| 01***06 | Nut, Regular Hexagon (M8-1.25) | 12 |
| 01***36 | Washer,Radio Controlled Slag Handling | 6 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Cylinder Head : Turbocharger
| 61***00 | Turbocharger Ass'Y,(T04b-59) | 1 |
| GA***00 | Clamp | 3 |
| GA***01 | Bolt | 6 |
Electrical System
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Alternator (25a)
| 60***30 | Alternator A. (25a),(With Hardening Pulley) | 1 |
| KD***57 | Bearing,Ball? Front | 1 |
| KD***80 | Collar | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Alternator (35a)
| 60***20 | Alternator A. (35a),(With Hardening Pulley) | 1 |
| KD***57 | Bearing,Ball? Front | 1 |
| KD***80 | Collar | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Alternator (50a)
| 60***90 | Alternator A. (50a),(With Hardening Pulley) | 1 |
| SD***X0 | Washer | 1 |
| SD***X0 | Fan | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Alternator And Mounting (25a? 35a) (Bracket Less Type)(#92938-)
| 01***45 | Bolt,(For Suction? Reversible Fan) | 1 |
| 01***35 | Bolt,(Cold Weather Spec.) | 1 |
| 01***40 | Bolt,(Shim 3-Piece) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Alternator And Mounting (25a? 35a) (Bracket Mounting Type)(#86423-92937)
| 01***40 | Bolt,(Dust And Dirt Protection) | 1 |
| 01***70 | Bolt,(With Wear Guard) | 1 |
| 01***35 | Bolt,(Cold Weather Spec.) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Alternator And Mounting (50a) (Bracket Mounting Type)
| 01***30 | Bolt,(For France Noise Suppression) | 1 |
| 01***70 | Bolt,(With Wear Guard) | 1 |
| 01***35 | Bolt,(Cold Weather Spec.) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Starting Motor (5.5kw)
| 60***90 | Starting Motor Ass'Y,(5.5kw) | 1 |
| KD***30 | Bracket,Center | 1 |
| KD***50 | Clutch Ass'Y,Over Running | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Starting Motor (7.5kw)
| 60***50 | Starting Motor Ass'Y,(7.5kw) | 1 |
| KD***60 | Shift Lever Assembly | 1 |
| KD***40 | Spring,Spring | 4 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Electrical System : Starting Motor And Mounting (5.5kw?7.5kw)
| 01***35 | Bolt - Torque Converter Totransmission Mounting | 3 |
| 01***30 | Bolt, Mounting - Front Hand Rails | 3 |
| 01***36 | Washer,Radio Controlled Slag Handling | 3 |
Engine Kit
Komatsu : S6d105-1tt(S/N 86423-Up) : Engine Kit : Gasket Kit
| 07***18 | O-Ring,(See Fig.1601-29?1602-17) | 1 |
| 07***70 | O-Ring,(For Intake Air Cover) | 1 |
| 07***00 | O-Ring,(F4350-65a1 -5 ) | 1 |
Fuel System
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Additionl Fuel Filer
| 07***12 | Gasket,Mechanical Pump Piping | 2 |
| 60***00 | Fuel Filter Ass'Y | 1 |
| 60***20 | Cartridge,Pref | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Filter And Piping
| 01***30 | Bolt,(For France Noise Suppression) | 2 |
| 01***25 | Bolt, Mount Engine Oil Drain To Fuel Tank | 2 |
| 01***30 | Washer,Spring(Sandy?Dusty Terrain S.) | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Injection Pump (Coupling)
| DK***00 | Bolt | 1 |
| DK***00 | Washer,Lock | 2 |
| DK***00 | Coupling,Cross | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Injection Pump (Feed Pump)
| DK***20 | Bolt, Joint | 1 |
| DK***20 | Pump,Priming | 1 |
| DK***20 | Housing | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Injection Pump (Governor) (1/2)
| DK***00 | Spring,Governor | 1 |
| DK***20 | Guide Lever Ass'Y | 1 |
| DK***00 | Adapter | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Injection Pump (Governor) (2/2)
| DK***80 | Shim? 0.5mm | 0 |
| DK***00 | Washer,Spring | 1 |
| DK***40 | Gasket,Air Compressor | 2 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Injection Pump (Pump)
| 61***60 | Injection Pump Ass'Y | 1 |
| 61***60 | Injection Pump Ass'Y,(Farming Spec.) | 1 |
| DK***10 | Washer,Spring | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Injection Pump And Piping (With Air Compressor)
| 01***70 | Bolt | 4 |
| 01***20 | Bolt,(Large Capacity Type) (Std) | 1 |
| 01***25 | Bolt,(Sandy? Dusty Terrain Spec.) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Injection Pump And Piping (Without Air Compressor) (Farming Spec.)
| 01***70 | Bolt | 4 |
| 01***20 | Bolt,(Large Capacity Type) (Std) | 1 |
| 01***25 | Bolt,(Sandy? Dusty Terrain Spec.) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Fuel Nozzle And Spill Pipe
| 01***55 | Bolt,(For Trimming Dozer) | 12 |
| 01***55 | Screw | 12 |
| 01***25 | Washer,Spring?(Sandy And Dusty Spec.) | 12 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Solenoid And Mounting
| 01***20 | Bolt | 4 |
| 01***50 | Bolt - Torque Converter Totransmission Mounting | 2 |
| 01***20 | Bolt,See Fig. K4010-11a0 | 4 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Fuel System : Water Separator
| 07***60 | O-Ring,(For Pc750?800?1800) (A2610) | 1 |
| 60***00 | Water Separator A.,(4d105-5h? 4d105-5t) | 1 |
| 60***60 | Plug,Drain (4d105-5h? 4d105-5t) | 1 |
Lubricating Oil System
Komatsu : S6d105-1tt(S/N 86423-Up) : Lubricating Oil System : Lubricating Oil Cooler
| 01***25 | Bolt,(Without Auto Priming System) | 5 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 2 |
| 01***35 | Bolt,(Without Auto Priming System) | 16 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Lubricating Oil System : Lubricating Oil Cooler (Cold Terrain Spec.)
| 01***25 | Bolt,(Without Auto Priming System) | 7 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 2 |
| 01***35 | Bolt,(Without Auto Priming System) | 12 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Lubricating Oil System : Lubricating Oil Filter And Mounting
| 01***70 | Bolt | 1 |
| 01***25 | Bolt,(Sandy? Dusty Terrain Spec.) | 5 |
| 01***35 | Bolt, Mounting - Flywheel Housing End | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Lubricating Oil System : Lubricating Oil Piping
| 01***16 | Bolt,(For Slag Handling) | 2 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 1 |
| 01***40 | Bolt,(For Position Fixing) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Lubricating Oil System : Lubricating Oil Pump And Suction Pipe
| 01***25 | Bolt,(Without Auto Priming System) | 3 |
| 01***30 | Bolt,(Cold Terrain Spec.) | 1 |
| 01***45 | Bolt,(S6d155-4b) | 1 |
Komatsu : S6d105-1tt(S/N 86423-Up) : Lubricating Oil System : Turbocharger Lubricating Oil Piping
| 01***22 | Bolt,(Cold Terrain Spec.) | 2 |
| 01***35 | Bolt, Mounting - Flywheel Housing End | 2 |
| 01***20 | Bolt,(Forwarded Individually Parts) | 2 |
S6D105-1TT(S/N 86423-UP) serial number reference
The engine serial number plate is located on the left side of the engine block or near the valve cover. The prefix is the engine model code (S6D105-1TT) stamped on the plate, followed by the serial number starting at 86423 for this specific variant.
| Prefix | Identifies | Notes |
|---|---|---|
| S6D105-1TT | Turbocharged, aftercooled, inline-6 diesel engine | Serial range 86423-UP. Source: published references catalog listing and DK Engine Parts equipment guide. No specific prefix letters identified beyond the engine model code itself in the provided sources; the engine model serves as the primary identifier for this serial block. Confirm with dealer for specific machine application prefixes (e.g., WA, PC) tied to this engine serial block. |
Frequently asked questions
What engine does the Komatsu S6D105-1TT (S/N 86423-UP) use?
It uses the Komatsu S6D105-1TT, a 6-cylinder, turbocharged, direct-injection diesel engine from the 6D105 series, delivering approximately 170 horsepower.
What is the operating weight of the machine powered by this engine?
Operating weight varies by configuration and series. For the WA250-1LC wheel loader, it is approximately 34,000 to 35,000 lb. For excavators like the PC200-3, it ranges from 40,000 to 45,000 lb depending on the boom and stick configuration.
What replaced the S6D105-1TT engine?
The S6D105-1TT was succeeded by the S6D105E-1 series and later the SAA6D107E-1 series, which feature electronic fuel injection and higher emissions compliance for Tier 3 and Tier 4 standards.
What S6D105-1TT(S/N 86423-UP) owners discuss
What are the known powertrain and hydraulic behaviors for the Komatsu S6D105-1TT engine series?
The S6D105-1TT is a turbocharged, direct-injection diesel engine delivering approximately 170 horsepower and 550 lb-ft of torque. It is widely noted for smooth operation and high fuel efficiency compared to earlier generation engines. The engine is paired with Komatsu’s hydraulic system, which relies on precise pump and valve coordination. Community consensus indicates that Komatsu hydraulic systems are generally robust but sensitive to oil condition and filter maintenance. If all hydraulic functions become slow simultaneously, the issue typically stems from shared components such as the main pump, engine speed, or hydraulic oil temperature rather than individual cylinders. When the machine is weak only when hot, internal leakage in the pump, main control valve, or motors is a common cause due to decreased oil viscosity at operating temperature. The engine and hydraulic system must be diagnosed together; if engine RPM drops heavily under load, the hydraulic system may be overloading the engine or the engine may be unable to produce expected power. The S6D105-1TT is often found in WA250-1LC wheel loaders (serial 86423-Up) and other mid-size construction equipment. Note that Dash 6 machines in the broader Komatsu line had known valve problems, particularly on PC150 and PC120 models, which can affect resale value and reliability perceptions. The line is generally designed to wear out complete machines all at once, meaning if a hydraulic pump fails, the engine may not be far behind in terms of wear. Have your dealer verify the specific hydraulic pressure settings for your machine's configuration/series as they vary by application. (170 hp, 550 lb-ft; 125 kW, 745 N·m)
What undercarriage or wear patterns are typical for machines equipped with this engine type?
Machines with the S6D105-1TT engine, such as the WA250-1LC wheel loader, experience significant wear on components like bushings, bearings, and track pads due to continuous load and environmental exposure. Worn-out bushings can lead to noise and vibration, while worn bearings may cause premature failure of the tracks. Track tension and undercarriage wear are critical maintenance areas; a machine that drifts or pulls while travelling should not immediately be diagnosed as having a failed travel motor. Check mechanical conditions first, including track tension on both sides, mud or debris packed into one undercarriage, roller condition, and track-chain condition. If mechanical resistance is similar but one track consistently runs slower, hydraulic or final-drive diagnosis becomes more relevant. Test the symptom in both forward and reverse to gather useful diagnostic information. Components like pins and bushings are subjected to significant wear and tear in used Komatsu equipment. Inspect for damage that may require specialized tools for repair. Have your dealer verify the undercarriage wear limits for your specific machine model. (Varies by configuration/series)
What are the common engine quirks per the S6D105-1TT series?
The S6D105-1TT engine is known for reliability but can suffer from power loss under heavy digging or loading loads if airflow or fuel delivery is restricted. Common causes include clogged air filters, fuel filters, or blocked fuel tank vents. Intake hoses and charge-air hoses on turbocharged engines must be checked for loose clamps or damage. Engine overheating during heavy excavation is often due to material packed between heat exchangers (radiator, hydraulic oil cooler, charge-air cooler) rather than internal engine failure. If temperature rises during heavy work but falls when idling, cooling capacity may be marginal. If coolant is repeatedly expelled or the system becomes highly pressurized shortly after a cold start, deeper engine diagnosis may be required. The engine uses a direct injection fuel system with turbocharged aspiration. Oil and coolant capacities are critical for optimal operation; refer to the engine model specifications for refill capacities. The S6D105-1TT is distinct from the S6D102E series and other variants; ensure the correct engine identification plate is consulted. Have your dealer verify the exact cooling system pressure and flow specifications for your machine's configuration/series. (Varies by configuration/series)
What are the common electrical or sensor issues associated with this engine?
Komatsu excavators and equipment rely 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 failure, or machines that randomly shut down. If the engine will not start, check the battery state of charge, battery terminals, engine and chassis grounds, main starter cable, starter relay, and control circuit. A battery can show acceptable voltage until the starter is loaded; perform a proper load and voltage-drop test before ordering a starter. If the engine cranks but does not start, check fuel level, fuel quality, fuel filters, water separator, and air entering the fuel supply. If the machine stopped starting immediately after a filter replacement, check the work that was just performed before assuming an expensive high-pressure component failed. Multiple fault codes often point to battery, grounds, or connectors. Komatsu also produces many equipment sizes and generations, so electrical systems and control strategies are model-specific. Always identify the exact machine before using service specifications. Have your dealer verify the electrical system diagnostics for your specific machine model. (Varies by configuration/series)
What should be checked when buying a used machine with the S6D105-1TT engine (S/N 86423-Up)?
When buying a used machine with the S6D105-1TT engine (serial 86423-Up, typically found in WA250-1LC wheel loaders), verify the exact serial-prefix specification sheet and installed attachment package. Check the engine for signs of overheating, such as coolant leaks or pressurization issues. Inspect the hydraulic system for leaks, stuck components, and inadequate fluid levels. Test all hydraulic functions cold and hot to identify internal leakage that may only appear at operating temperature. Check the undercarriage for worn bushings, bearings, and track pads. Verify the condition of the air and fuel filters, and check for air entering the fuel supply. Inspect the cooling package for material packed between heat exchangers. Check the electrical system for intermittent starting, dashboard failures, or random shutdowns. Confirm the engine number and model suffix to ensure it matches the S6D105-1TT designation and not a related variant like the S6D102E series. Have your dealer verify the engine and hydraulic system specifications for your specific machine model. (Varies by configuration/series)
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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