Troubleshooting the Mitsubishi MS120-2: Issues & Solutions for Better Performance

[MikePhua]

The Mitsubishi MS120-2 is a well-regarded machine in the world of heavy equipment, especially known for its durability and reliability. While not as well-known as some of its competitors, such as Caterpillar or Komatsu, Mitsubishi’s machinery has a loyal following for its solid engineering and relatively easy maintenance. However, like any older or specialized equipment, it is not immune to wear and tear. Operators and owners of the MS120-2 often encounter specific issues that need to be addressed to maintain optimal performance. In this article, we’ll take a closer look at some common issues with the Mitsubishi MS120-2, how to troubleshoot them, and best practices for ensuring long-lasting operation.
Overview of the Mitsubishi MS120-2
The Mitsubishi MS120-2 is a compact crawler excavator designed for various construction tasks, including digging, lifting, and material handling. Known for its strong engine and efficient hydraulics, the MS120-2 offers solid performance even in challenging conditions. However, its age and the availability of replacement parts may present challenges to modern operators.
Despite these challenges, the MS120-2 remains popular among those who value reliability, ease of use, and its relatively simple design compared to newer, more complex machinery. However, to get the best out of this machine, it’s essential to keep an eye on some recurring issues that tend to arise over time.
Common Problems with the Mitsubishi MS120-2

1. Engine Performance Issues
   

One of the most frequent problems with the MS120-2 is engine-related issues. These can include rough idling, loss of power, and difficulty starting. These issues can stem from a variety of factors:

• Fuel System Problems: The fuel system, including filters, injectors, and fuel lines, can become clogged with dirt and debris over time, affecting engine performance.
  
• Air Filter Blockages: Air filters play a crucial role in maintaining engine efficiency. A clogged air filter can reduce airflow, causing the engine to run inefficiently and increasing fuel consumption.
  
• Glow Plug Failures: For cold-start issues, worn or damaged glow plugs can prevent the engine from starting properly.
  

Troubleshooting Engine Problems
To address engine performance issues, begin by checking the fuel filter and replacing it if it appears dirty or clogged. Clean or replace the air filter regularly to ensure the engine gets enough air. Additionally, if the engine is struggling to start, inspect the glow plugs and replace them if necessary.

1. Hydraulic System Failures
   

Another area where the MS120-2 may experience issues is the hydraulic system. Given that the hydraulic components control essential functions like the arm, boom, and bucket, a failure in this system can severely impact performance. Common hydraulic problems include:

• Leaking Hoses: Over time, hoses and seals may begin to wear, leading to fluid leaks and reduced hydraulic pressure.
  
• Low Hydraulic Fluid: Insufficient fluid can lead to sluggish or unresponsive hydraulics, making it difficult to lift, lower, or rotate the boom or bucket.
  
• Pump Failures: The hydraulic pump itself may wear out over time, leading to low pressure or failure to operate certain hydraulic functions.
  

Troubleshooting Hydraulic Issues
Start by checking the hydraulic fluid levels and top them off if necessary. If the system is still unresponsive, inspect the hoses for leaks and replace any damaged components. If the hydraulic pressure continues to be low, the pump or valve may need to be serviced or replaced.

1. Undercarriage Wear
   

The undercarriage of the MS120-2, like any tracked machine, is subject to significant wear and tear. The tracks, rollers, and sprockets all experience heavy stress as the machine moves and operates. Over time, the following issues may arise:

• Track Tension Issues: Tracks that are either too tight or too loose can cause excessive wear on the undercarriage components.
  
• Worn Rollers and Sprockets: The rollers and sprockets can become worn down, which may cause the tracks to misalign or slip, reducing the machine’s efficiency and increasing the risk of further damage.
  

Troubleshooting Undercarriage Problems
Check the track tension regularly and adjust it according to the manufacturer’s specifications. Inspect the rollers and sprockets for signs of wear or damage, and replace them if necessary to prevent further wear on the tracks.

1. Electrical and Control System Malfunctions
   

Electrical issues can also occur in older machines like the MS120-2. Problems can range from simple issues like blown fuses to more complex ones, such as malfunctioning sensors or wiring issues that affect the control system.

• Battery and Charging System Issues: The battery or alternator may fail to charge properly, leading to starting issues or loss of power to the electrical system.
  
• Sensor Failures: Malfunctioning sensors can cause errors in the machine’s operation, leading to incorrect readings or failure of certain functions.
  

Troubleshooting Electrical Problems
Start by checking the battery and charging system. If the machine is having difficulty starting, test the battery and alternator to ensure they are functioning correctly. Inspect the wiring for any signs of wear or damage. If the electrical system is malfunctioning, diagnosing specific sensor or control system failures may require specialized diagnostic tools.
Preventive Maintenance: Best Practices for the Mitsubishi MS120-2

1. Regular Fluid Checks
   Consistent fluid checks are essential for maintaining the MS120-2’s performance. Ensure that engine oil, hydraulic fluid, and coolant levels are maintained according to the manufacturer’s guidelines.
   
2. Inspect Filters and Seals
   Regularly inspect and replace air, fuel, and hydraulic filters. These components are essential for maintaining optimal performance, especially in dusty or muddy environments where clogging can occur more easily.
   
3. Track and Undercarriage Maintenance
   Monitor the condition of the tracks, rollers, and sprockets. Regularly adjust track tension and replace any worn-out undercarriage components to ensure smooth operation.
   
4. Electrical System Inspections
   Perform routine checks on the electrical system, ensuring that all wiring and sensors are in good working order. Look for any loose connections or damaged components that could cause malfunctions.
   
5. Keep the Machine Clean
   A clean machine runs more efficiently and lasts longer. Regularly wash off dirt and debris from the undercarriage and engine compartment to prevent buildup that could affect the machine’s performance.
   

Real-World Experiences with the Mitsubishi MS120-2
Operators who have worked with the MS120-2 have shared that, despite its age, it can be a reliable and effective piece of equipment when properly maintained. One operator mentioned that the hydraulic system in their MS120-2 had some issues with pressure loss, but after replacing a few hoses and ensuring that the fluid levels were topped off, the machine ran like new. Another operator had issues with the electrical system, but they found that replacing a faulty fuse and tightening some loose wiring solved the problem.
Conclusion: Keeping the Mitsubishi MS120-2 Running Smoothly
The Mitsubishi MS120-2, like any older piece of equipment, requires attentive care and regular maintenance to continue performing well. By staying on top of engine issues, hydraulic system checks, undercarriage maintenance, and electrical diagnostics, operators can extend the life of this durable machine and keep it running smoothly for years to come. With the right maintenance approach and timely troubleshooting, the MS120-2 can continue to serve its purpose in a variety of construction and excavation tasks.