Hitachi EX 120-2 Repair and Maintenance Support

[MikePhua]

The Hitachi EX 120-2 is a compact hydraulic excavator known for its durability, efficiency, and versatility in various construction and mining applications. Although built to last, like any heavy machinery, it requires regular maintenance and occasional repairs to keep it in optimal working condition. For owners and operators of the EX 120-2, understanding common repair issues, maintenance practices, and repair support can ensure prolonged machine life and efficiency.
This article provides a detailed overview of common repair concerns for the Hitachi EX 120-2, how to address them, and the best sources for repair support. It also delves into the importance of proper maintenance and provides advice on maintaining your machine to minimize costly repairs.
The Hitachi EX 120-2: An Overview
The EX 120-2 is a mid-sized hydraulic excavator from Hitachi's EX series, popular in the 1990s and early 2000s. It is equipped with a powerful diesel engine and advanced hydraulic systems, making it well-suited for demanding tasks such as digging, lifting, grading, and demolition. The machine is recognized for its compact design, allowing it to operate in tight spaces while maintaining impressive digging depth and lifting capacity.
With a robust construction, the EX 120-2 quickly gained a reputation for reliability in the construction and mining sectors. However, as with all older machines, users often face challenges regarding maintenance and repair as the equipment ages.
Common Repair Issues with the Hitachi EX 120-2
Even with its reliability, the Hitachi EX 120-2 can experience specific repair issues over time. These problems can arise from wear and tear, improper maintenance, or even manufacturer defects that surface with age. Below are some of the most common repair concerns:
1. Hydraulic System Failures
The hydraulic system is the heart of any excavator, and for the EX 120-2, hydraulic failures can be among the most serious issues. These problems often manifest as poor digging performance, slow response from the arm, or total hydraulic failure.
Common Causes:

• Hydraulic pump wear or failure
  
• Leaking hydraulic hoses or fittings
  
• Contaminated hydraulic fluid
  
• Hydraulic valve malfunctions
  

Solution:
If hydraulic issues arise, the first step is to check the hydraulic fluid levels and cleanliness. Replacing filters and fluid can often solve minor problems. For more severe issues, such as pump wear or valve failure, a professional inspection is required. In some cases, replacing components may be necessary.
2. Engine Performance Problems
The engine is another critical component that can face issues such as overheating, oil leaks, or performance drops. Common symptoms include reduced power, smoke from the exhaust, or strange noises coming from the engine compartment.
Common Causes:

• Dirty air filters
  
• Clogged fuel injectors
  
• Worn-out seals or gaskets
  
• Lack of proper maintenance and oil changes
  

Solution:
Regular engine servicing is crucial. Ensure that the air and fuel filters are changed according to the manufacturer’s recommendations. If engine performance drops, it’s advisable to check for any leaks or unusual wear on the seals and gaskets. Regular oil changes, especially using the right grade of oil, will also help maintain engine health.
3. Electrical System Failures
Electrical issues can cause problems such as failure to start, intermittent operation of lights or gauges, and electrical shorts. These issues are typically linked to the wiring, battery, or alternator.
Common Causes:

• Corroded or loose battery terminals
  
• Faulty alternator or charging system
  
• Damaged wiring harnesses
  
• Fuse issues
  

Solution:
For electrical issues, first inspect the battery terminals and ensure they are clean and tightly connected. If the alternator is not charging correctly, it may need to be replaced. A thorough inspection of the wiring harness can help identify damaged cables that need repairing or replacing.
4. Track and Undercarriage Wear
The undercarriage, including tracks, rollers, and sprockets, faces constant wear during operation. Track issues can result in uneven ground contact, affecting the machine’s stability and efficiency.
Common Causes:

• Track misalignment
  
• Worn-out sprockets or rollers
  
• Excessive wear on the track links
  

Solution:
Regular inspection of the undercarriage is important to catch wear early. Ensure that tracks are aligned correctly and that the rollers and sprockets are not excessively worn. Regular lubrication and periodic adjustments to the track tension will help extend the lifespan of these components.
5. Boom and Arm Hydraulic Cylinders
Boom and arm hydraulic cylinders can become damaged over time due to stress or poor maintenance, leading to oil leaks and reduced performance. This issue is often noticed when the boom or arm fails to hold a position or moves erratically.
Common Causes:

• Seal damage in hydraulic cylinders
  
• Contaminated hydraulic fluid
  
• Improper maintenance or misuse
  

Solution:
Replacing damaged seals and ensuring the hydraulic fluid is clean can resolve minor issues. If the cylinders themselves are damaged, they may need to be rebuilt or replaced.
Repair Support for Hitachi EX 120-2
When it comes to repairing or maintaining the Hitachi EX 120-2, professional repair support is invaluable. Several resources are available for owners and operators of the machine:
1. Hitachi Dealers and Service Centers
Hitachi has a wide network of authorized dealers and service centers around the world. These centers are staffed with experienced technicians who are familiar with the EX 120-2 and have access to original parts and diagnostic tools. If you encounter a serious issue or need parts replacement, seeking support from an authorized Hitachi service center ensures that repairs are done according to manufacturer standards.
2. Third-Party Mechanics and Workshops
For less critical repairs, or if you’re looking for more cost-effective solutions, third-party mechanics and independent workshops can be an option. These technicians often have experience working on older Hitachi models, including the EX 120-2. However, it is important to ensure that the mechanic uses quality parts and understands the specific requirements of the machine.
3. Online Forums and Communities
Online forums and communities, such as those dedicated to heavy equipment repairs, can be a helpful resource for troubleshooting common issues with the Hitachi EX 120-2. These forums often feature advice from other owners who have faced similar challenges and can offer tips, solutions, or even recommendations for parts suppliers.
Best Practices for Maintaining the Hitachi EX 120-2
Preventing major repairs requires a proactive approach to maintenance. Regular inspections, fluid changes, and system checks can go a long way in ensuring the longevity and performance of your Hitachi EX 120-2. Some best practices include:

• Routine Fluid Checks: Regularly check hydraulic fluid levels and change the fluid according to the manufacturer’s schedule to keep the hydraulic system functioning efficiently.
  
• Engine and Filter Maintenance: Ensure that the air, fuel, and oil filters are replaced as recommended, and always use high-quality oils and filters.
  
• Undercarriage Maintenance: Inspect the undercarriage frequently for wear and adjust track tension to prevent uneven wear patterns.
  
• Electrical System Checks: Regularly clean and inspect the battery terminals, and ensure that the alternator is charging correctly to prevent electrical failures.
  
• Service the Hydraulic System: Regularly inspect and service the hydraulic cylinders and pumps to avoid leaks and maintain performance.
  

Conclusion
The Hitachi EX 120-2 is a robust and reliable machine, but like any piece of heavy equipment, it requires proper care and attention to avoid costly repairs. By understanding common repair issues and following best practices for maintenance, operators can maximize the lifespan and efficiency of their machine. Whether seeking professional repair support or performing basic maintenance, ensuring the EX 120-2 remains in top condition will pay dividends in performance, safety, and overall cost-effectiveness.