Water Contamination in Hydraulic Systems

[MikePhua]

Background on the Machine
The 2014 Takeuchi T770 is a compact track loader widely used for construction and landscaping tasks. Takeuchi, founded in Japan in 1963, became one of the first companies to mass-produce compact track loaders with superior maneuverability. The T770 model, popular for its 74-horsepower engine and hydraulic versatility, has sold thousands globally, known for reliability and ease of maintenance.
Discovery of Water in the Hydraulic System
During routine maintenance, the hydraulic fluid in a T770 was found contaminated with water. Investigation revealed the top of the hydraulic reservoir cap had broken, leaving only threads and the plug base. Water could easily enter the recess of the plug and accumulate in the reservoir over time. The previous owner admitted the breakage occurred 200–300 hours prior, assuming the threads and plug base still maintained a seal.
Risks of Water Contamination
Water in hydraulic fluid is detrimental to system performance and component longevity. The key risks include:

• Additive breakdown – Hydraulic oils contain additives to reduce wear and corrosion. Water accelerates their degradation.
  
• Corrosion – Metal surfaces such as pumps, cylinders, and valves are exposed to oxidation, leading to pitting and scoring.
  
• Reduced lubrication – Water lowers oil viscosity, increasing metal-to-metal contact and wear.
  
• Foaming and cavitation – Water vaporizes under pressure and heat, causing cavitation, which can damage pumps and valves.
  

Even if the machine currently operates normally, prolonged water exposure can act like a "ticking time bomb," leading to unexpected failures.
Inspection and Mitigation Measures
Several steps are recommended to address and monitor water contamination:

• Fluid Replacement – Drain the hydraulic fluid in stages, replacing 50–100% at a time, until the new fluid appears clean.
  
• Filter Check – Inspect and replace hydraulic filters, which may have trapped water or contaminants.
  
• Water Analysis – Laboratory analysis can quantify water content in parts per million (ppm), ensuring it meets manufacturer tolerances.
  
• System Drying – Operate the loader with fresh fluid, running hydraulic functions to circulate oil and evaporate residual moisture.
  
• Seal Repair – Replace the broken reservoir cap to prevent future ingress. Ensure caps and threads are correctly installed and fully sealed.
  

Preventive Advice

• Always inspect hydraulic reservoirs for visible damage or compromised seals during routine checks.
  
• Store hydraulic machinery in sheltered areas to prevent water entry from rain or washdowns.
  
• Schedule fluid testing annually or every 1,000 operating hours to detect water or other contamination early.
  

Conclusion
While the Takeuchi T770 in question currently functions normally, water exposure in hydraulic systems poses a high risk to internal components. Thorough fluid replacement, filter inspection, and preventive maintenance can mitigate long-term damage. Operators should remain vigilant, as even minor water contamination can accelerate wear and reduce system reliability over time.
Glossary of Terms

• Cavitation – Formation and collapse of vapor bubbles in fluid, which can erode metal surfaces.
  
• PPM (Parts per Million) – A unit measuring the concentration of water or contaminants in hydraulic fluid.
  
• Hydraulic Additives – Chemicals added to oil to improve lubrication, prevent corrosion, and reduce wear.
  
• Viscosity – The resistance of fluid to flow, critical for proper hydraulic system operation.