The Komatsu 6D105 is a six-cylinder diesel-engine family found in older construction and industrial equipment. The core engine designation is useful, but it is not enough by itself to order every internal or external part. A correct order starts with the full model marking, the machine and engine serial numbers, the old part number, and clear photos of the removed component.
Komatsu 6D105 quick specifications
The table below separates the stable family-level information from data that is configuration-specific. This distinction matters because a number copied from one loader, dozer or excavator brochure may not describe another 6D105 installation.
| Item | Verified family-level information | Ordering implication |
|---|---|---|
| Configuration | Inline six-cylinder, four-cycle, water-cooled diesel | Confirm the complete model and suffix rather than ordering from “six-cylinder Komatsu” alone. |
| Bore × stroke | 105 mm × 125 mm | Do not treat nominal bore as proof that a liner, piston or ring set matches the installed engine. |
| Displacement | Approximately 6.49–6.5 L | Use displacement as an identification clue, not as a unique parts key. |
| Aspiration | Family references distinguish 6D105 and turbocharged S6D105 versions | Photograph the model plate and intake/exhaust arrangement before ordering related parts. |
| Power and torque | Varies by engine suffix, rating and machine installation | Use the correct machine specification or engine shop manual; avoid a universal horsepower claim. |
| Oil, coolant, weight and dimensions | Installation-dependent | Confirm the exact equipment model and service publication before filling fluids or planning a replacement. |
Technical basis: the Japan Construction Mechanization Association’s historical 6D105/S6D105 specification table records six cylinders, 105 × 125 mm bore and stroke, and 6.5 L displacement. Komatsu’s current parts resources also organize service information by machine-specific references rather than by a generic engine name alone. See the historical 6D105 technical reference and Komatsu quick-reference parts guides.
How to identify the correct Komatsu 6D105 version
Identification should be evidence-based. Start with the machine plate and the engine plate, then compare those records with the old component. A clear photograph often prevents a costly assumption about a suffix, production change or previous repair.
1. Record the complete model
Write down every character visible on the engine identification plate. A prefix or suffix can separate naturally aspirated and turbocharged versions or distinguish a machine-specific arrangement. Do not shorten the marking to “6D105” when requesting parts.
2. Record both serial numbers
The machine serial number and engine serial number serve different purposes. Keep both. Komatsu’s own parts tools use model and serial information to narrow the correct service items, which is why a serial number is more useful than a visual resemblance.
3. Photograph the old part number
Clean only enough of the removed part to expose stamped, cast or printed markings. Photograph the entire part and the marking in separate images. A casting number may identify a raw casting rather than the complete service assembly, so preserve context.
4. Measure only what can be measured reliably
For pistons, rings, liners and bearings, record dimensions with suitable tools and state whether the measurement is nominal, worn or machined. A worn bore or a previously ground crankshaft can mislead a buyer who reports only a single dimension.
For a broader explanation of why plates, serial numbers and old-part evidence matter, review our engine identification workflow before ordering parts and the more detailed serial-number and parts-verification example. The brands differ, but the verification discipline is the same.
Why power, capacity and dimensions cannot be one universal number
Search results often combine specifications from different machines. That creates an easy trap: a power rating from one application is presented as if it applies to every 6D105. In practice, rated speed, aspiration, fuel-system setting, cooling package and accessory load can change the published output. Oil and coolant capacity can also include machine-specific pans, radiators, hoses and coolers.
For a section-by-section purchasing plan covering liners, pistons, rings, bearings, gaskets and valve-train components, use the Komatsu 6D105 engine parts rebuild checklist. It turns the identification evidence below into an overhaul ordering workflow.
Parts that require the most verification before ordering
Piston, piston ring and cylinder liner group
These parts work as a matched sealing and wear system. Confirm the piston crown and bowl geometry, pin size, ring-groove arrangement, ring thicknesses, liner outside profile and sealing features. Also determine whether the block or crankshaft has been machined. The available 6D105 piston kit, 6D105 piston ring set and 6D105 cylinder liner are relevant product references, but each link still requires model, serial and old-part confirmation before purchase.
If the old piston shows scoring, broken lands or abnormal crown damage, replacing parts without finding the cause can repeat the failure. Our guide to common diesel-engine piston failure causes provides a diagnostic starting point.
Bearings, thrust control and crankshaft condition
Bearing selection depends on the crankshaft journal condition and the required size or grade. Never assume standard size because the engine model is correct. Ask the machine shop for measured journal diameters and confirm whether the crankshaft has been ground. A live 6D105 connecting-rod bearing listing can help identify the intended product family, but measured data must control the final order.
Gasket sets and cylinder-head sealing
A complete overhaul gasket kit and a cylinder-head gasket are not automatically interchangeable purchasing choices. Kit contents can differ, and the head gasket must match the correct engine version and sealing arrangement. Compare every required seal with the packing list before teardown begins. Relevant live references include the 6D105 overhaul gasket kit and 6D105 head gasket.
Valve train, lubrication and cooling parts
Valve guides, seats and valves should be checked as a system, including stem diameter, guide condition, seat geometry and cylinder-head machining history. The 6D105 valve guide is one available reference. For lubrication and cooling components, compare ports, mounting pattern and old numbers; the live 6D105 oil-cooler assembly should be treated as an application-specific component, not a universal fit claim.
Parts-ordering checklist
- Full equipment model and machine serial number.
- Complete engine designation and engine serial number.
- Old OEM or service part number, photographed in place and after removal where possible.
- Clear photos of the entire part, mounting face, ports, connectors and identifying marks.
- Measured bore, pin, ring, liner or journal data when internal parts are involved.
- Standard or repair size, supported by machine-shop measurements.
- Requested quantity and whether related seals, clips or hardware are needed.
- Any known previous rebuild, machining or component substitution.
Komatsu describes machine-specific parts guides and serial-number-driven ordering as tools for finding the correct items. That supports a simple rule: the more complete the identification evidence, the lower the risk of a wrong order. A general rebuild example is available in our engine rebuild parts checklist and buying guide, although its model-specific recommendations must not be transferred to a 6D105.
Send the engine model, engine serial number, machine model and serial number, old part number, dimensions and clear photos. We will use that evidence to narrow the correct option before you order.
Frequently asked questions
What are the key Komatsu 6D105 engine specs?
Family-level references identify an inline six-cylinder, four-cycle, water-cooled diesel with a 105 mm bore, 125 mm stroke and approximately 6.49–6.5 L displacement. Power, torque, capacities, weight and dimensions depend on the exact suffix and machine installation.
How do I identify the correct Komatsu 6D105 version?
Record the complete engine designation, engine serial number, machine model and machine serial number. Then compare the old part number, photos, mounting details and measurements with the parts reference for that specific serial range.
Where can I find the engine serial number?
Inspect the engine identification plate and the locations specified in the correct machine or engine manual. Do not rely on a universal location description because access and mounting can differ by installation. Photograph the plate and nearby engine features together.
What should I verify before ordering Komatsu 6D105 parts?
Verify the complete model and serial data, the old part number, standard or repair size, critical dimensions, visible design details and any evidence of previous machining. For external assemblies, also compare ports, mounting pattern and connectors.
Which rebuild parts are commonly evaluated together?
Pistons, rings and liners are normally evaluated as a wear and sealing group; crankshaft condition determines bearing size; and cylinder-head work may involve valves, guides, seats and gaskets. This does not mean one universal kit contains every item, so confirm the required list for the actual engine.
Sources consulted: JCMA historical 6D105/S6D105 technical table; Komatsu quick-reference parts guides; My Komatsu parts and manual resources. Exact service procedures, limits and torque values must come from the correct manual for the machine and engine serial range.