Why the Same Komatsu Engine Uses Different Part Numbers & Real Examples)

If you have ever searched for a certain "komatsu engine parts", you may have noticed that for seemingly identical components, there are multiple different part numbers. This is not an isolated case. It is one of the most common reasons for incorrect orders: merely based on the engine model, it is impossible to ensure the compatibility between the parts.

Komatsu machines often have production updates, regional configurations, and option packages.  Engine spare parts are customized for different countries and regions, incorporating specialized parts tailored to local operating conditions. Consequently, part numbers for engines of the same model may vary.That’s why Komatsu parts catalogs frequently rely on machine model + serial number (serial breaks) to confirm the correct part.

Next，I explains why the same engine can lead to different part numbers, and how to confirm the correct part quickly—without trial and error.

Engine model ≠ machine configuration

An engine family (for example, a Komatsu “D102” series) can appear across different equipment types—excavators, loaders, dozers, even forklifts. Those machines differ in:

• available mounting space

• required starting torque

• wiring layout and connector direction

• electrical system and protection requirements

• emission configuration and control strategy

This is exactly why Komatsu recommends confirming with part number + serial number, because the same machine name (and even the same engine family) can have multiple valid configurations over time.

The 6 most common reasons part numbers differ (even with the “same engine”)

(1) Different equipment platform (excavator vs loader vs forklift)

The component may be “the same function,” but built as a different “arrangement” to fit the machine. A starter for a forklift application can be listed under the same Komatsu number family, but the mounting, terminals, or packaging specs may differ.

(2) Output power / torque requirement differs

Heavy-duty cycles or cold-start requirements can change starter output. Komatsu lists starter motors with different power levels (for example 4.5 kW vs 5.5 kW)—both are valid parts, but not always interchangeable.

(3) Gear reduction vs direct drive design

Gear-reduction starters deliver higher torque with different internal structure and sometimes different packaging. Komatsu explicitly lists gear reduction type starters as separate products.

(4) Teeth count & pinion specs

Even if voltage matches, tooth count and pinion dimensions can change. Komatsu’s official specs often include tooth count (e.g., 10 teeth) and voltage.

(5) Serial breaks & production revisions

Komatsu catalogs commonly split fitment into ranges—“up to S/N XXXXX” and “from S/N XXXXX onward.” Your machine may be the same model name, but built in a different year/config revision.

(6) New vs Reman part numbers

Komatsu sells Genuine Reman versions as separate part numbers with their own specification pages and warranty terms.

Real example: Komatsu S6D102 engine can use multiple starter motor part numbers

Let’s use the starter motor as a practical example of why the “same engine family” can still lead to different valid part numbers.

Even across Komatsu starter listings and common field references, you’ll notice that starter motors are defined by specs and arrangement, not just “S6D102 engine.” For the S6D102 family, it’s common to see multiple starter options such as:

• 600-863-4110 — typically listed as 24V / 4.5 kW / 10T, often referenced for S6D102 applications (e.g., PC200-6 / wheel loader listings).

• 600-863-5110 — often listed as 24V / 5.5 kW / 10T, used in higher-output starter configurations in some machine arrangements.

• 600-863-4410 — commonly listed as 24V / 4.5 kW, but tooth count can vary by listing (some show 10T, some show 11T), so this one must be verified by the original label and teeth count.

  
  

You can also see the same “spec-first” pattern directly on Komatsu’s official parts site, where starters are distinguished by output power, voltage, teeth count, and design type, for example:

• 600-863-5131 — Starting Motor with specs including 24V / 5.5 kW / 10 teeth.

• R600-863-5131 — Starter, Gear Reduction type with 24V / 5.5 kW / 10 teeth (Komatsu Genuine Reman).

• R600-863-4511 — Starter, Gear Reduction type with 24V / 4.5 kW (Komatsu Genuine Reman).

When would one starter be used instead of another?

In practice, the correct starter depends on arrangement (machine application), serial breaks, and physical specs:

• 4.5 kW (e.g., 600-863-4110) is commonly seen where standard cranking output is sufficient, and the machine’s original arrangement matches 24V + 10T.

• 5.5 kW (e.g., 600-863-5110 / 600-863-5131) is typically used in configurations that require higher starter output, but you still must match teeth count + mounting + terminal/plug layout.

• Gear-reduction vs direct-drive is not interchangeable: if your machine is equipped with a gear-reduction starter, you must match that design (Komatsu lists gear-reduction starters as separate items, including reman versions).

• Tooth count differences (10T vs 11T) are a hard stop: if teeth count doesn’t match, engagement issues can occur. That’s why some part numbers like 600-863-4410 must be confirmed by counting teeth and checking the old label, because listings are inconsistent.

What this tells you

• A “starter motor” is not one universal part, even for the same engine family (S6D102).

• The correct part depends on configuration (arrangement), machine application, serial breaks, and key specs (24V, kW, teeth count, design type).

• The safest path is matching by part number + machine serial number + physical confirmation, not engine name alone. (This is exactly why Komatsu part identification relies on S/N breaks and arrangement checks.) 

FAQ

Q1: Why do I see multiple part numbers when searching Komatsu engine parts for the same engine model?
A: Komatsu engine parts are often defined by the machine arrangement, not just the engine family name. Different equipment platforms (excavator/loader/dozer), serial number breaks, option packages, and design revisions can all lead to different valid part numbers. Always confirm using machine model + serial number + original part label.

Q2: Are aftermarket Komatsu parts safe to use?
A: Aftermarket Komatsu parts can be a cost-effective solution for repair and fleet maintenance—as long as the part is correctly matched. The key is verification: confirm the old part number, specs, and fitment details (connector/mounting/teeth count for starters). A wrong-fit “aftermarket” order is usually a verification issue, not a category issue.

Q3: How do I confirm the correct Komatsu starter motor before ordering?
A: For a Komatsu starter, confirm these four items first:

1. Old starter label/part number (best reference)

2. Voltage (12V or 24V)

3. Teeth count (e.g., 10T vs 11T)

4. Mounting flange / bolt pattern
   If you can, send photos of the old starter and the machine nameplate—this prevents wrong orders.

Q4: Can I replace a 4.5 kW Komatsu starter with a 5.5 kW starter?
A: Not automatically. Higher kW can mean different internal design and arrangement. You must match teeth count, mounting, and electrical/terminal layout. If the machine was originally configured for a specific starter type (including gear reduction vs direct drive), swapping without confirmation can cause fitment or engagement problems.

Q5: What does “gear reduction starter” mean, and why does it matter?
A: A gear reduction starter uses an internal gear system to produce higher torque. It often has different dimensions and arrangement compared to direct-drive starters. If your machine is equipped with a gear reduction design, you should match that type when replacing.

Q6: What information should I provide to get the right aftermarket Komatsu parts quickly?
A: To match aftermarket Komatsu parts accurately, provide:

• Machine model + serial number

• The old part number or label photo

• Clear photos of the part (no special angles required)