Komatsu D45 Engine Damage Likely Caused by Turbo Fragment Ingestion and Requires Full Head Inspection

[MikePhua]

Komatsu D45 Dozer Background
The Komatsu D45 crawler dozer was part of Komatsu’s mid-size earthmoving lineup during the late 1970s and early 1980s. Known for its mechanical simplicity and rugged undercarriage, the D45 was widely used in forestry, grading, and small-scale mining. Komatsu, founded in 1921 in Japan, became a global leader in construction equipment by the 1980s, with the D-series dozers contributing to its reputation for reliability and durability.
The D45 typically featured a naturally aspirated or turbocharged diesel engine, mechanical transmission, and a robust track frame. While not as electronically advanced as modern machines, its mechanical systems were serviceable and resilient—making it a favorite among independent operators and rural contractors.
Incident Overview and Initial Symptoms
In this case, the D45 had recently undergone undercarriage refurbishment, including new rollers and rebuilt tracks. The engine was reported to start easily and run smoothly, with no oil consumption—until the turbocharger catastrophically failed. A fragment from the turbo’s compressor wheel entered the intake manifold before the engine could be shut down.
Following the incident:

• The engine began to bind when cranked
  
• Oil was found exiting an injector port
  
• A deep knocking sound was heard during turnover
  
• A mechanic suspected internal damage reaching the crankshaft
  

These symptoms suggest that the turbo fragment may have damaged the piston crown, bent a valve, or even fractured a connecting rod.
Turbocharger Failure and Ingestion Risks
Turbochargers operate at speeds exceeding 100,000 RPM. When a compressor wheel fails, its fragments can become high-velocity projectiles. If these enter the combustion chamber, they can:

• Dent or puncture the piston crown
  
• Bend intake or exhaust valves
  
• Damage cylinder liners
  
• Cause hydraulic lock if oil is forced into the cylinder
  

In this case, the presence of oil at the injector port may indicate a cracked piston or breached cylinder wall allowing oil to migrate upward.
Repair Strategy and Inspection Priorities
Before any repair decisions are made, the cylinder head must be removed. This allows for:

• Visual inspection of piston crowns and valve faces
  
• Detection of bent rods or cracked liners
  
• Assessment of head surface integrity and valve seat damage
  

If the damage is limited to the head or piston crown, welding may be possible. A skilled welder can repair cast iron heads using nickel rods and controlled heat cycles. However, if the crankshaft or connecting rods are compromised, a full rebuild or engine replacement may be necessary.
Used Engine Availability and Cost Considerations
Given the age of the D45, sourcing a replacement engine is challenging. The original engine model may no longer be in production, and used units are rare. Options include:

• Searching salvage yards specializing in Komatsu equipment
  
• Checking with overseas suppliers in regions where older Komatsu machines are still active
  
• Considering engine swaps with compatible models from the same era
  

Cost-wise, a full rebuild could exceed $6,000 in parts and labor, while a used engine—if found—might range from $3,000 to $5,000 depending on condition.
Field Advice and Practical Experience
One technician recalled removing a piston from a CAT 3406 in three pieces after a similar ingestion event. Despite minimal external symptoms, internal damage was severe. This underscores the importance of not relying solely on sound or cranking resistance to assess damage.
Another operator shared that welding a cracked block was possible with proper preheating and post-weld cooling, but only if the crack was accessible and not near critical bearing surfaces.
Recommendations for Next Steps

• Remove the cylinder head and inspect all combustion chambers
  
• Check piston travel and rod alignment manually
  
• Drain and inspect engine oil for metal shavings
  
• Evaluate turbocharger remnants and intake tract for additional debris
  
• Consult with a machinist before attempting any weld repairs
  

Conclusion
The Komatsu D45’s engine damage following turbo failure is likely due to fragment ingestion, which may have compromised the piston, valves, or even the crankshaft. While the machine’s age complicates parts sourcing, a methodical teardown and inspection will clarify the repair path. Whether through welding, rebuilding, or engine replacement, the decision should balance cost, downtime, and long-term reliability. For legacy machines like the D45, mechanical simplicity remains both a challenge and an opportunity for skilled hands.