Replacing Hydraulic Pump Hoses on a Hitachi EX200-5

[MikePhua]

Hitachi’s EX200-5 and Its Hydraulic System Design
The Hitachi EX200-5 is part of the fifth-generation lineup of the EX200 series, a mid-size excavator class that became widely popular in the 1990s and early 2000s. Hitachi Construction Machinery, founded in 1970, built its reputation on durable hydraulic systems and efficient engine integration. The EX200-5 features a dual-pump hydraulic system that powers both the boom and travel functions, with fluid routed through a network of high-pressure hoses and steel lines.
The machine’s pump-to-valve chest hoses are critical for distributing hydraulic flow to the control valves. These hoses are subject to constant vibration, pressure surges exceeding 3,000 psi, and thermal cycling—making them one of the most failure-prone components in the system.
Terminology:
- Valve Chest: A block of directional control valves that distribute hydraulic flow to various actuators. - Dual-Pump System: A configuration where two hydraulic pumps operate in tandem to supply fluid to different circuits.
Challenges in Sourcing and Replacing OEM-Spec Hoses
One of the recurring issues with the EX200-5 is the difficulty in sourcing OEM-spec hoses, particularly those with uncommon diameters and complex bends. The original hoses connecting the pump to the valve chest are 7/8-inch in diameter and feature long 90° and 30° bends. These bends are not just for routing convenience—they’re engineered to reduce stress and accommodate movement from engine mounts and frame flex.
In many regions, hydraulic shops stock standard sizes like 1-inch or 3/4-inch, but 7/8-inch hose is rare. Some technicians resort to modifying the original fittings by cutting off the bent sections and welding on ferrules to accept more common hose sizes. While this can work temporarily, it introduces risks:

• Welded joints may not match the original flow geometry
  
• Stiff hose material can transfer vibration directly to fittings
  
• Misalignment can cause premature failure or leaks
  

Terminology:
- Ferrule: A metal sleeve crimped onto the end of a hose to secure it to a fitting. - Flow Geometry: The internal shape and path of fluid through a fitting or hose, affecting pressure and turbulence.
Material Selection and Vibration Management
In one case, Gates 4-wire hydraulic hose was used to replace the original lines. While Gates is known for high-quality products, the 4-wire construction proved too rigid for the EX200-5’s dynamic environment. The hose failed mid-length due to constant flexing and vibration from the engine mounts.
To mitigate this, technicians should consider:

• Using 2-wire hose with sufficient pressure rating but more flexibility
  
• Adding vibration dampeners or hose supports
  
• Avoiding sharp bends near crimped ends
  
• Installing protective sleeves to reduce abrasion
  

In high-vibration zones, hose flexibility is often more critical than burst pressure. A slightly lower-rated hose with better movement tolerance can outperform a stiffer, overbuilt alternative.
Terminology:
- Burst Pressure: The maximum pressure a hose can withstand before rupturing. - Vibration Dampener: A device or material that absorbs oscillations to protect hydraulic components.
Dealer Support and Lead Time Issues
Hitachi’s global dealer network varies in responsiveness. In some regions, dealers may take days to confirm availability or pricing for OEM hoses. This delay can be costly, especially when the machine is scheduled to work in sensitive environments like tidal zones or municipal contracts.
To reduce downtime, operators often:

• Keep spare hoses and fittings for critical circuits
  
• Build relationships with local hydraulic shops that offer custom crimping
  
• Maintain a log of hose dimensions, bend angles, and fitting types
  
• Use digital calipers and angle gauges to replicate OEM geometry
  

In one coastal project, an EX200-5 was scheduled to begin work in a tidal reclamation area. The operator couldn’t wait for OEM parts and had a local shop fabricate a replacement using a combination of 1-inch hose and welded adapters. The machine ran successfully, but the operator noted increased vibration and planned to replace the hose with a factory unit once available.
Terminology:
- Custom Crimping: The process of attaching hose ends using shop-specific dies and pressure settings. - Tidal Reclamation: Land development in coastal zones involving excavation and fill operations.
Recommendations for Long-Term Hose Reliability
To ensure hose longevity and system integrity, consider the following:

• Use OEM hoses when available, especially for pump-to-valve connections
  
• If fabricating replacements, match bend angles and hose flexibility
  
• Avoid mixing hose types with different internal diameters
  
• Inspect hose routing for pinch points and abrasion zones
  
• Replace both hoses in a pair to maintain balanced flow and wear
  

In older machines like the EX200-5, hydraulic performance depends heavily on hose condition. A single compromised line can lead to pressure drops, erratic valve behavior, and increased fuel consumption due to pump inefficiency.
Terminology:
- Pressure Drop: A reduction in hydraulic pressure due to flow restriction or leakage. - Balanced Flow: Equal distribution of hydraulic fluid across circuits to maintain consistent performance.
Conclusion
Replacing the pump hoses on a Hitachi EX200-5 is more than a parts swap—it’s a precision task that demands attention to geometry, material flexibility, and vibration dynamics. While aftermarket solutions can bridge the gap, they must be carefully matched to the machine’s operating environment. With proper planning and a clear understanding of hydraulic behavior, operators can restore full functionality and extend the life of their equipment—even when OEM support is slow to arrive.