Komatsu 4D95S-W-1F-AP(S/N 23318-UP)
Maintenance schedule, common problems & OEM parts breakdown
The Komatsu 4D95S-W-1F-AP is a four-cylinder diesel engine used in the GD85A and GD105A bulldozer series. It delivers approximately 137 horsepower and is built for heavy-duty earthmoving. The engine is part of the 95 Series family, which includes variants like the 4D95L and 4D95S. Production years for this specific configuration span from the late 1990s through the early 2000s. It succeeded earlier 4D95 models and was later replaced by newer emission-compliant engines. The engine is designed for compact to mid-size dozers with operating weights ranging from 9,182 to 87,083 lb.
Across the 95 Series, changes included updates to emissions compliance and fuel injection systems. The 4D95S-W-1F-AP is significant in the used market due to its reliability and widespread use in compact dozers. Parts availability remains strong, with many components cross-referenced across similar 4D95 variants. The engine's durability makes it a common choice for rebuild and replacement in older Komatsu equipment.
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 4D95S-W-1F-AP(S/N 23318-UP) specifications
Engine
| Model | 4D95S-W-1F-AP |
| Serial Range | 23318-UP |
| Cylinders | 4 |
| Displacement | 3.26 L (198.9 cu in) |
| Bore | 95 mm (3.74 in) |
| Stroke | 115 mm (4.53 in) |
| Gross Power | varies by configuration/series |
| Net Power | varies by configuration/series |
| 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)
| 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 |
| 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 |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
Komatsu 4D95S-W-1F-AP(S/N 23318-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 4D95S-W-1F-AP(S/N 23318-UP) beyond the schedule
Predictive Maintenance & Fluid Analysis
Use KOWA fluid analysis at every 500-hour interval to monitor engine oil wear metals and hydraulic fluid cleanliness. Check coolant SCA levels at 500 hours to prevent scaling and corrosion. Monitor DEF levels daily on Tier 4 models. Track fuel consumption trends to detect injector issues early. Inspect air filter restriction indicators before each shift. Replace hydraulic return filters at 500 hours to maintain system cleanliness and protect pumps.
Corrective & Common Repairs
Address poor revving and rough idle by inspecting injectors and checking for air leaks in the fuel system. Replace worn cylinder liners and pistons if compression drops below spec. Fix oil leaks by replacing seals and gaskets, especially around the water pump and oil pan. Check starter motor and alternator connections if starting issues occur. Replace fuel filters regularly to prevent clogging. Inspect belts and hoses for cracks or wear during every 250-hour service.
Overhaul & Rebuild Points
Plan a full engine overhaul at 10,000 to 15,000 hours or when wear metals exceed limits in KOWA reports. Replace cylinder liners, pistons, rings, and bearings as a set. Resurface the cylinder head and replace valve guides and seats. Inspect the crankshaft for wear and replace if necessary. Use a complete overhaul gasket kit for reassembly. Ensure proper valve clearance adjustment after rebuild to maintain performance and fuel efficiency.
Seasonal & Environment Servicing
In cold weather, check coolant freeze point and use appropriate winter-grade oil. Drain water from the fuel separator daily to prevent icing. In dusty environments, clean the radiator and oil cooler fins frequently to prevent overheating. Inspect air filter elements more often and replace as needed. Check undercarriage tension and track shoe condition regularly on dozers working in abrasive conditions. Grease all pivot points daily to protect against dirt ingress.
4D95S-W-1F-AP(S/N 23318-UP) common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 07281-00197 | Clamp,(With Pre-Fuel Filter) | Fuel system service | Check fitment → |
| 600-311-1190 | Plate? Caution,Fuel Filter | Fuel system service | Check fitment → |
| 600-311-6220 | Cartridge,Fuel Filter | Fuel system service | Check fitment → |
| 600-311-9600 | Fuel Filter Ass'Y | Fuel system service | Check fitment → |
| 600-311-7440 | Cartridge,Fuel Filter | Fuel system service | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
4D95S-W-1F-AP(S/N 23318-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 |
| CA441 | Battery voltage too low | Weak battery or charging system failure | Replace the battery or alternator and check the voltage regulator |
| CA442 | Battery voltage too high | Alternator overcharging or voltage regulator failure | Replace the alternator or battery and check the voltage regulator |
| CA122 | Intake air pressure high voltage | Intake pressure sensor malfunction or actual overpressure | 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 pressure sensor malfunction or actual overpressure | Diagnose the fuel rail pressure sensor or pump lines |
| CA452 | Common rail pressure sensor feedback value too low | Fuel rail pressure sensor malfunction or low pressure condition | 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 |
| CA111 | Internal engine controller fault | ECM internal failure | Replace or reprogram the ECM |
| AA10NX | Air cleaner clogging | Dirty or blocked air filter | Replace the air filter |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
4D95S-W-1F-AP(S/N 23318-UP) attachments & work tools
Bulldozer Blade Configurations
The 4D95S-W-1F-AP engine is installed in the D20P-6, D20PL-6, D20Q-6, D20S-6, D21P-6, D21A-6, D21S-6, and D21QG-6 dozer series. Typical blade capacities for this class range from 2.0 to 2.5 cubic meters (2.6 to 3.3 cubic yards), varying by specific dozer model and blade type (straight, semi-universal, or universal). Factory guarding options include ROPS/FOPS certified cabs and side guards for the undercarriage, as documented in the Komatsu shop manual for the 95 Series engine range.
Excavator Attachment Families
This engine powers compact excavators such as the PC75UU-2, PC75UD-2, PC75UU-2E, and PC75UD-2E. Standard work tools include standard digging buckets, grading buckets, and trenching buckets with widths typically between 0.5 to 1.0 meters (1.6 to 3.3 feet). Hydraulic breaker and hammer attachments are supported via auxiliary hydraulic circuits, requiring specific flow and pressure settings verified against the machine's operation and maintenance manual.
Wheel Loader Bucket Options
The 4D95S-W-1F-AP engine is used in the WA65-6, WA70-6, WA70-7, and WA80-6 wheel loaders. Typical bucket capacities for these models range from 1.5 to 2.5 cubic meters (2.0 to 3.3 cubic yards) for general purpose applications. Multi-purpose and rock buckets are available as factory options, with mounting systems compatible with the standard loader arm geometry for this weight class.
Hydraulic and Coupler Systems
Work tools require auxiliary hydraulic connections for functions such as tilt, rotation, or breaker operation. The specific hydraulic kit arrangement, including hose routing and valve configurations, varies by the host machine model (e.g., PC75 excavator vs. WA65 loader) and is detailed in the respective equipment operation and maintenance manual. Quick couplers, if equipped, must match the pin diameter and mounting pattern specified for the specific dozer or excavator model.
All 4D95S-W-1F-AP(S/N 23318-UP) assemblies by section
Every catalogued assembly group for the Komatsu 4D95S-W-1F-AP(S/N 23318-UP). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Cooling System
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cooling System : Water Pump And Cooling Fan
| 01***16 | Screw | 5 |
| 01***20 | Screw | 2 |
| 01***25 | Bolt,(With Corrosion Resistor) | 6 |
Cylinder Block
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Camshaft And Tappet
| 01***20 | Screw | 2 |
| 04***16 | Fitting Wedge | 1 |
| 62***31 | Thrust Washer | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Crankshaft
| 61***20 | Bolt | 1 |
| 62***00 | Crankshaft Ass'Y | 1 |
| 62***00 | Main Metal Ass'Y | 5 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Cylinder Block
| 01***55 | Bolt, Mount Tube To Switch Pump | 8 |
| 01***16 | Screw | 1 |
| 01***20 | Screw | 2 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Flywheel And Flywheel Housing
| 01***30 | Bolt | 6 |
| 01***30 | Bolt - Lower Oil Cooler Outlet Tubemounting | 11 |
| 01***40 | Bolt,(Shim 3-Piece) | 3 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Front Cover And Gear
| 01***10 | Bolt | 1 |
| 01***70 | Bolt,(For 75a Alternator) | 1 |
| 01***16 | Bolt | 2 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Oil Pan (Double Bottom Type)(#36389-74638)
| 01***16 | Bolt, Mount Solenoid Valve | 24 |
| 01***16 | Screw | 24 |
| 07***12 | Washer, Gasket,(Without Thermo Sensor) (K1) | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Oil Pan (Double Bottom Type)(#74639-)
| 01***20 | Bolt,(Forwarded Individually Parts) | 24 |
| 07***12 | Washer, Gasket,(Without Thermo Sensor) (K1) | 1 |
| 07***16 | Gasket,(For Pc750-6) (See Fig.A2110) | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Oil Pan(#23318-74638)
| 01***16 | Bolt, Mount Solenoid Valve | 24 |
| 01***16 | Screw | 24 |
| 07***16 | Gasket,(For Pc750-6) (See Fig.A2110) | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Oil Pan(#74639-)
| 01***20 | Bolt,(Forwarded Individually Parts) | 24 |
| 07***16 | Gasket,(For Pc750-6) (See Fig.A2110) | 1 |
| 62***12 | Pan,Oil | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Block : Piston And Connecting Rod
| 04***12 | Ring, Snap | 8 |
| 62***40 | Piston (S) | 4 |
| 62***00 | Piston Ring Ass'Y,Per Cylinder | 4 |
Cylinder Head
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Head : Air Cleaner And Mounting
| 01***30 | Bolt,(Water Separator Spec.) | 1 |
| 01***16 | Bolt,(With Alternator Cover Type) | 2 |
| 01***06 | Nut | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Head : Air Intake Manifold And Connection(#23318-30907)
| 01***65 | Stud | 1 |
| 01***65 | Bolt,(With Water Separator) | 3 |
| 01***75 | Bolt,(For Shipping) | 8 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Head : Air Intake Manifold And Connection(#30908-)
| 01***65 | Stud | 1 |
| 01***12 | Bolt,(With Speedometer) | 4 |
| 01***65 | Bolt,(With Water Separator) | 3 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Head : Cylinder Head
| 01***20 | Bolt, Hose Clamps (Inlet And Return Line Hoses) | 4 |
| 01***32 | Washer,(Not Used With Emergency Str.) | 17 |
| 02***04 | Plug, Pipe | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Head : Cylinder Head Cover
| 61***10 | Cap, Oil Filler | 1 |
| 61***20 | Screw | 3 |
| 61***30 | Washer,(B) | 3 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Head : Exhaust Manifold And Muffler
| 01***25 | Grub Screw | 4 |
| 01***45 | Bolt, Bracket Mounting | 8 |
| 01***11 | Nut (M14-1.50 Thd), Nut; Was 01582-01411 | 2 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Head : Exhaust Manifold And Muffler (With Spark Arrester)
| 01***25 | Grub Screw | 4 |
| 01***45 | Bolt, Bracket Mounting | 8 |
| 01***11 | Nut (M14-1.50 Thd), Nut; Was 01582-01411 | 2 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Cylinder Head : Rocker Arm
| 01***12 | Bolt,(Without R.P.C.U.) | 1 |
| 01***65 | Bolt,(For Alternator Bracket Mount) | 5 |
| 61***30 | Nut | 8 |
Electrical System
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Electrical System : Alternator (15a)
| 60***60 | Alternator A. (15a) | 1 |
| KD***70 | Cover | 1 |
| KD***30 | Retainer | 2 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Electrical System : Alternator (25a)
| 60***10 | Alternator A. (25a) | 1 |
| KD***57 | Bearing,Ball? Front | 1 |
| KD***11 | Rear Bracket Ass'Y | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Electrical System : Alternator And Mounting (15a)
| 01***25 | Bolt,(With Corrosion Resistor) | 1 |
| 01***45 | Bolt | 1 |
| 01***06 | Nut | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Electrical System : Alternator And Mounting (25a)
| 01***55 | Bolt,(With Engine Stop Motor Type) | 1 |
| 01***30 | Bolt | 1 |
| 01***11 | Nut,(For Center Guard) | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Electrical System : Starting Motor (2.8kw)
| 60***70 | Starting Motor Ass'Y,(2.8kw) | 1 |
| KD***60 | Bracket,Center | 1 |
| KD***50 | Stopper,Piston | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Electrical System : Starting Motor And Mounting (2.8kw)
| 01***30 | Bolt | 2 |
| 07***95 | O-Ring,Transmission Strainer | 1 |
| (6***0) | Starting Motor Ass'Y,(2.8kw) (See Fig.A6210-B0b3) | 1 |
Engine Kit
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Engine Kit : Gasket Kit
| 01***12 | Washer,Lock (Noise Suppression Spec.) (K2) | 1 |
| 07***65 | O-Ring,Injection Pump Case | 1 |
| 07***85 | O-Ring,(Without Fuel Level Gauge) | 1 |
Fuel System
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Filter And Piping
| 01***65 | Bolt,(With Water Separator) | 2 |
| 07***12 | Gasket,Mechanical Pump Piping | 1 |
| 07***12 | Gasket,(Without Air Compressor Type) (K1) | 4 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Filter And Piping (For Large Capacity)(#56149-)
| 01***65 | Bolt,(With Water Separator) | 2 |
| 07***12 | Gasket,Mechanical Pump Piping | 1 |
| 07***12 | Gasket,(Without Air Compressor Type) (K1) | 4 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Injection Pump (Feed Pump)
| DK***20 | Bolt, Joint | 1 |
| DK***00 | Valve,Check | 2 |
| DK***20 | Pump,Priming | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Injection Pump (Governor) (1/2)
| DK***00 | Shim? 2.00mm,(High Altitude Spec.) | 0 |
| DK***00 | Adapter | 1 |
| DK***80 | Nut | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Injection Pump (Governor) (2/2)
| DK***20 | Lever | 1 |
| DK***40 | Gasket,Air Compressor | 2 |
| DK***20 | Capsule,Spring | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Injection Pump (Pump) (1/2)
| 62***10 | Injection Pump Ass'Y | 1 |
| 62***11 | Injection Pump Ass'Y | 1 |
| DK***30 | Bearing | 0 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Injection Pump (Pump) (2/2)
| DK***40 | Shim? 0.50mm, Shim, 0.50mm; Was Dk029311-0040 | 0 |
| DK***90 | Shim? 0.25mm, Shim, 0.25mm; Was Dk029311-0590 | 0 |
| DK***00 | Sleeve,Control | 4 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Injection Pump And Piping
| 01***35 | Stud | 4 |
| 01***12 | Bolt | 2 |
| 01***25 | Screw | 2 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Fuel Nozzle And Spill Pipe
| 07***50 | Tube,Spill | 1 |
| 07***55 | Tube,Spill | 1 |
| 07***85 | Clip | 2 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Fuel System : Water Separator And Piping(#43240-)
| 01***80 | Stud | 2 |
| 01***25 | Bolt,(With Corrosion Resistor) | 2 |
| 01***08 | Nut,See Fig. K4010-04a0 | 2 |
Lubricating Oil System
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Lubricating Oil System : Lubricating Oil Filter
| 60***40 | Cartridge,Engine Oil Filter (D31s) | 1 |
| 60***41 | Cartridge,Engine Oil Filter (D31s) | 1 |
| 60***20 | Plate? Caution,(Italian-English) | 1 |
Komatsu : 4d95s-W-1f-Ap(S/N 23318-Up) : Lubricating Oil System : Lubricating Oil Pump And Suction Pipe
| 01***12 | Bolt,(See Fig.0501) | 1 |
| 01***16 | Screw | 6 |
| 01***55 | Bolt,(With Engine Stop Motor Type) | 1 |
4D95S-W-1F-AP(S/N 23318-UP) serial number reference
The engine serial number plate is located on the left side of the engine block, typically near the injection pump or on the valve cover. The prefix is the first six characters of the machine model code (e.g., D20PL-6), which identifies the dozer series and generation; the engine serial range 23318-UP confirms the specific 4D95S-W-1F variant installation.
| Prefix | Identifies | Notes |
|---|---|---|
| D20PL-6 | Crawler Dozer | Series 6 generation. Engine 4D95S-W-1F installed S/N 23318-UP. |
| D20PLL-6 | Crawler Dozer (LGP) | Series 6 generation. Engine 4D95S-W-1F installed S/N 23318-UP. |
| D20Q-6 | Crawler Dozer | Series 6 generation. Engine 4D95S-W-1F installed S/N 23318-UP. |
| D20S-6 | Crawler Dozer | Series 6 generation. Engine 4D95S-W-1F installed S/N 23318-UP. |
Frequently asked questions
What is the engine type?
The Komatsu 4D95S-W-1F-AP is a four-cylinder, water-cooled, turbocharged diesel engine. It is part of the 95 Series family and delivers approximately 137 horsepower. It is used in GD85A and GD105A bulldozers.
What is the operating weight range?
The operating weight varies by configuration and series. For the GD85A and GD105A dozers equipped with this engine, weights range from 9,182 to 87,083 lb depending on attachments and undercarriage setup.
What replaced the 4D95S-W-1F-AP?
The 4D95S-W-1F-AP was replaced by newer emission-compliant engines in the Komatsu lineup. Specific successor models vary by region and machine series, with later generations adopting Tier 4 Final or Stage V compliant power units.
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