Caterpillar 140G Motor Grader Problems

[MikePhua]

Introduction to the 140G
The Caterpillar 140G is a mid-size motor grader introduced in the early 1980s as part of the "G Series" lineup. Designed for road construction, grading, and heavy maintenance, the 140G quickly gained popularity due to its durability and precise blade control. The machine typically features a 6-cylinder diesel engine coupled with a sleeve metering fuel injection system and a robust transmission for smooth operation under heavy loads. Over its production period, the 140G became a mainstay in municipal and private fleets, valued for reliability and long service intervals.

Common Engine Stalling Issue
Operators have reported intermittent stalling during operation, often after extended periods or under heavy load. Symptoms include the engine running normally at full RPM and suddenly dying, requiring a 5–10 minute wait before restarting. This issue is particularly common in older models and can be caused by several fuel system-related factors.

Fuel System Troubleshooting

• Fuel Filters and Air Draws
  • First line of inspection involves checking primary and secondary fuel filters for blockage.
    
  • Air in the fuel lines can cause temporary engine shutdown.
    
• Fuel Tank and Cap Venting
  • A plugged fuel cap vent can create vacuum in the tank, restricting fuel flow.
    
  • Inspecting and loosening the fuel cap often allows air to rush into the tank, restoring flow.
    
• Lift Pump (Fuel Transfer Pump)
  • Located on the front of the injection pump housing, typically a small gear pump with a shearable pin.
    
  • Wear in this pump can cause inconsistent fuel delivery, particularly under high-demand situations like uphill grading or prolonged heavy loads.
    
  • Replacement or internal check valve servicing is often a cost-effective solution.
    
• Tank and Line Obstructions
  • Sludge, slime, or sediment buildup at the tank bottom or in supply lines can reduce fuel flow.
    
  • Flushing the tank, checking shutoff valves, and inspecting delivery lines prevent low-pressure events.
    

Operational Insights

• Machines with low-mounted fuel tanks are more susceptible to stalling due to gravity-feed limitations.
  
• Fuel system behavior varies between units; some use a cam-driven lift pump while others rely on gravity or side-mounted pumps.
  
• Observing engine performance after prolonged high-load operation can help identify whether stalling is due to fuel starvation or pump wear.
  

Maintenance Recommendations

• Clean fuel caps and vents monthly to prevent vacuum formation.
  
• Inspect and clean fuel tanks periodically, especially older machines with potential sludge accumulation.
  
• Service lift pumps regularly, including checking shear pins and replacing one-way check valves.
  
• Maintain a log of fuel system performance during different operating conditions to identify patterns before failures occur.
  

Conclusion
The Caterpillar 140G remains a durable and widely used motor grader, but operators must remain vigilant regarding fuel system maintenance. Common stalling issues often relate to fuel cap venting, lift pump wear, and tank obstructions. Systematic inspection, cleaning, and preventative servicing help ensure reliable operation, reduce downtime, and extend the life of this classic grading machine. Regular attention to these details allows fleets to maintain productivity and avoid unexpected failures on the job site.