Komatsu PC400 Serial Number Identification and Field Preparation

[MikePhua]

The Komatsu PC400 excavator occupies an important place in the evolution of large hydraulic excavators. Machines in this size class are commonly used in quarrying, pipeline construction, forestry road building, and remote infrastructure projects. Because many PC400 units were deployed in rugged environments, it is not unusual to encounter older machines that have been sitting unused for years. When retrieving such a machine, understanding its serial number, configuration, and service requirements becomes essential.
A machine identified by serial number 10389 falls into the early production range of the PC400 series, a period when Komatsu was expanding its heavy‑duty excavator lineup to compete more aggressively with Caterpillar’s 375 and Hitachi’s EX400. These early PC400 units were known for their mechanical simplicity, robust steelwork, and dependable hydraulic systems.
Development History of the PC400 Series
Komatsu introduced the PC400 line as part of its strategy to strengthen its presence in the large‑excavator market during the late twentieth century. The company had already established itself with the PC300 and PC200 families, which became global bestsellers. The PC400 was designed to bridge the gap between mid‑sized excavators and the ultra‑heavy mining machines like the PC600 and PC800.
Key development goals included:

• Increasing digging force for quarry and pipeline work
  
• Improving hydraulic efficiency through variable‑displacement pumps
  
• Enhancing operator comfort with upgraded cabs
  
• Strengthening undercarriage components for rocky terrain
  

Komatsu’s global sales data from the era shows that the PC400 series became one of the company’s most widely adopted heavy excavators in North America and Asia. Many units were exported to remote regions, where their durability made them ideal for long‑term projects with limited support infrastructure.
Understanding Serial Numbers and Model Variants
Komatsu uses serial number ranges to identify production years and configuration types. The PC400 family includes variants such as:

• PC400 standard
  
• PC400LC long‑carriage
  
• PC400‑1, PC400‑2, PC400‑3 early generations
  
• PC400‑5 and PC400‑6 later refinements
  

Terminology notes:

• LC (Long Carriage): A wider and longer undercarriage designed for improved stability.
  
• Dash number: Indicates the generation of the machine, with higher numbers representing later updates.
  
• Serial number: A unique identifier used to determine production year, configuration, and parts compatibility.
  

A serial number in the low 10,000 range typically corresponds to early production, often associated with the PC400‑1 or PC400‑2 generation. These machines used mechanical fuel systems, simpler electronics, and early versions of Komatsu’s hydraulic control valves.
Preparing to Recover a Long‑Idle Machine
Retrieving a PC400 that has been sitting unused for two years requires careful planning. Machines stored in remote areas—such as half a mile off a highway in rugged terrain—often need a full fluid service before they can be safely started.
Essential service items include:

• Engine oil
  
• Hydraulic oil
  
• Swing gear oil
  
• Final drive oil
  
• Coolant
  
• Fuel filters and water separators
  
• Air filters
  
• Batteries
  

Older PC400 units typically use two large 12‑volt batteries wired in parallel to provide the necessary cold‑cranking amperage. In cold climates such as Alaska, higher‑capacity batteries are recommended to overcome thickened engine oil and sluggish hydraulic fluid.
Hydraulic and Engine Fluid Requirements
While exact capacities vary slightly by generation, early PC400 machines generally require:

• Several dozen gallons of hydraulic fluid
  
• Multiple gallons of engine oil
  
• Substantial coolant volume for the large diesel engine
  
• Gear oil for swing and final drives
  

Terminology notes:

• Hydraulic reservoir: The tank that stores hydraulic fluid for pumps and cylinders.
  
• Final drive: The planetary gear system that powers each track.
  
• Swing gear: The mechanism that allows the upper structure to rotate.
  

Because hydraulic contamination is a common issue in idle machines, it is wise to bring extra filters and enough fluid to perform at least a partial system flush.
Challenges of Remote Recovery
Recovering a large excavator in remote terrain presents unique challenges. Access roads may be soft, overgrown, or obstructed. Wildlife, weather, and limited daylight can complicate the process. In northern regions, machines often sink slightly into the ground over time, requiring additional effort to free the tracks.
A common field technique is to:

• Inspect all fluid levels before attempting to crank
  
• Prime the fuel system to remove air
  
• Warm the engine with external heaters if temperatures are low
  
• Check track tension and ensure the machine can move once started
  

Many operators also bring portable jump packs, diesel heaters, and spare hydraulic hoses to handle unexpected failures.
Anecdotes from the Field
Stories of recovering old Komatsu machines are common in remote construction regions. One operator recalled hiking through dense brush to reach a PC400 that had been abandoned after a storm washed out the access road. After replacing batteries and priming the fuel system, the machine started on the first attempt—a testament to Komatsu’s engineering.
Another crew in northern Canada revived a PC400 that had been idle for nearly five years. Despite frozen hydraulic lines and a seized track adjuster, the machine eventually crawled out under its own power, saving the team from having to disassemble it for transport.
These stories highlight the ruggedness of the PC400 platform and the importance of proper preparation.
Komatsu Company Background
Komatsu, founded in Japan in the early twentieth century, grew from a small mining equipment manufacturer into one of the world’s largest heavy machinery companies. By the time the PC400 series was introduced, Komatsu had already established global manufacturing plants and a strong dealer network.
The company’s success was built on:

• Standardized parts across multiple models
  
• Emphasis on durability and field serviceability
  
• Continuous refinement of hydraulic systems
  
• Strong export performance in North America, Australia, and Asia
  

Komatsu’s excavator sales consistently ranked among the top in the world, with the PC series becoming one of the most recognizable product lines in the industry.
Practical Recommendations for Owners and Operators

• Verify the exact model variant using the serial number plate.
  
• Bring sufficient fluids and filters when preparing to start a long‑idle machine.
  
• Use high‑capacity batteries in cold climates.
  
• Inspect hydraulic hoses for cracking before applying pressure.
  
• Check for rodent damage to wiring harnesses.
  
• Prime the fuel system thoroughly to avoid dry cranking.
  
• Allow the machine to warm up slowly to protect seals and pumps.
  

Conclusion
The Komatsu PC400 is a durable and historically significant excavator that continues to serve in demanding environments decades after its introduction. Understanding its serial number, configuration, and service requirements is essential when preparing to recover or restart an older unit. With proper planning and knowledge of the machine’s design, even long‑idle PC400s can often be brought back to life and returned to productive work.