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Pressurised Hydraulic systems are crucial in various industries, from construction and manufacturing to aviation and renewable energy.

Two large blue hydraulic valves in an industrial plant, with visible bolts and pipes around them, demonstrating the use of pressurized hydraulic systems in such applications
A dam with several sluice gates, one of which is open, allowing water to flow through, demonstrating the use of pressurized hydraulic systems in managing water flow
A close-up view of a wind turbine against a cloudy sky, demonstrating the use of pressurized hydraulic systems in adjusting the turbine blades for optimal performance.

Despite their robust design, hydraulic systems can encounter several issues that may lead to decreased efficiency, system failures, and costly downtime. 

In this post, we will explore common hydraulic system issues and provide a guide to identifying and troubleshooting these problems. By understanding these issues and their solutions, you can maintain the optimal performance and longevity of your hydraulic systems.

Common Hydraulic System Issues

1. Overheating

Problem: Overheating is a frequent issue in hydraulic systems and can lead to severe damage if not addressed promptly. Excessive heat can cause fluid breakdown, seal damage, and reduced system efficiency.

Causes:

  • Poor Design resulting in flow restrictions and or excessive internal oil velocities  
  • Insufficient or non existent Oil cooling. 
  • Restricted airflow to installed coolers from dirt and debris
  • High ambient temperatures
  • Overloaded system operations
  • Fluid viscosity too high or too low
  • Contaminated or degraded hydraulic fluid

Symptoms:

  • Unusually Noisy System
  • Hot Spots throughout the hydraulics system    
  • Slow or erratic actuator movements
  • Fluid temperature exceeding recommended levels
Close-up of hydraulic hoses and fittings, illustrating potential overheating issues in pressurized hydraulic systems, which can lead to severe damage if not addressed. Causes include poor design, insufficient cooling, restricted airflow, high ambient temperatures, overloaded operations, improper fluid viscosity, and contaminated or degraded hydraulic fluid. Symptoms include noisy systems, hot spots, slow or erratic actuator movements, and excessive fluid temperatures.

2. Fluid Contamination

Problem: Contamination of hydraulic fluid is a major cause of system failure. Contaminants can include dirt, metal particles, water, and other impurities that are either introduced in the form of external contamination or are created within the system from wear and tear.

Causes:

  • Poor or infrequent maintenance practices
  • Damaged seals, filters, or Tank lids and Breathers. 
  • Improper storage, handling and dispensing of oils and fluids
  • Ingress of moisture or external particles during use or from poor machine seals and  covers.

Symptoms:

  • Unusual noises such as knocking, whining or grinding.
  • Reduced system performance, such as loss of lifting power or drive torque
  • Increased wear and tear on components resulting in the more frequent replacement of parts. 
  • Blocked or damaged filters
  • Excessive Heat
  • Oil Leaks
Close-up of hydraulic fluid being poured, illustrating fluid contamination issues in pressurised hydraulic systems. Contaminants such as dirt, metal particles, water, and other impurities can cause system failure. Causes include poor maintenance practices, damaged seals and filters, improper storage and handling, and ingress of moisture. Symptoms include unusual noises, reduced system performance, increased wear and tear, blocked filters, excessive heat, and oil leaks.

3. Air Contamination

Problem: Air contamination occurs when air bubbles become entrapped in the hydraulic fluid, leading to aeration. 

Causes:

  • Leaks in suction lines
  • Low fluid levels in the reservoir
  • Incorrect bleeding procedures during maintenance and repairs.
  • Damaged or worn seals

Symptoms:

  • Foam or froth in the reservoir
  • Oil and Foam leaking or overflowing from the Reservoir
  • Erratic or Jerky and inaccurate actuator movements
  • Increased noise and vibration
  • Spongy or unresponsive controls
  • Low lifting power and Drive Torque  

Close-up of air bubbles in hydraulic fluid, illustrating air contamination issues in pressurized hydraulic systems. Causes include leaks in suction lines, low fluid levels in the reservoir, incorrect bleeding procedures, and damaged or worn seals. Symptoms include foam or froth in the reservoir, oil and foam leaking or overflowing, erratic or jerky actuator movements, increased noise and vibration, and spongy or unresponsive controls.

4. Cavitation

Problem: Cavitation is a condition where vapor bubbles form in the hydraulic fluid, leading to potential damage when these bubbles collapse.

Causes:

  • Low fluid levels
  • High fluid temperature
  • Inadequate pump inlet pressure
  • Fluid viscosity too high

Symptoms:

  • Unusual noise, like a rattling or knocking sound
  • Reduced pump efficiency
  • Visible damage to pump components
  • System performance degradation

5. Hydraulic Leaks

Problem: Leaks in hydraulic systems can cause significant fluid loss, reduced system pressure, environmental damage as well as serious safety issues from personnel lipping and Fire from oil touching hot surfaces.

Causes:

  • Worn or damaged seals, hoses and pipes.
  • Loose fittings or connections
  • Cracked or damaged components
  • Excessive system pressure
  • Excessive Operating temperatures. 

Symptoms:

  • Visible fluid on the ground or on and around components
  • Unusual Smells, (hydraulic Oil has a characteristic Smell)  
  • Oil Drips or Sprays (Larger high pressure oil leaks can be seen as well as heard)    
  • Drop in system pressure
  • Increased need for fluid top-ups
  • Decreased system efficiency
Close-up of worn and damaged hydraulic hoses, illustrating hydraulic leak issues in pressurised hydraulic systems. Causes include worn or damaged seals, hoses, and pipes, loose fittings or connections, cracked or damaged components, excessive system pressure, and excessive operating temperatures. Symptoms of hydraulic leaks include visible fluid on the ground or on and around components, unusual smells (hydraulic oil has a characteristic smell), oil drips or sprays (larger high-pressure oil leaks can be seen as well as heard), drop in system pressure, increased need for fluid top-ups, and decreased system efficiency.

6. Component Wear and Tear

Problem: Regular wear and tear of hydraulic components can lead to system inefficiencies and eventual failure if not monitored and addressed.

Causes:

  • Prolonged use without proper maintenance
  • Operating beyond design specifications
  • Inadequate lubrication
  • Contaminated or degraded fluid
  • Cavitation caused by over speed, wrong oil viscosity and or temperature range.

Symptoms:

  • Unusually loud noises or vibrations of pumps
  • Grinding Noises in Motors 
  • Slow or jerky movements of actuators
  • Reduced overall system performance such as low torque and power 
  • Visible damage to components such as Scratched rods on Cylinders,
  • Physical wear to internal components in pumps and Motors 
Close-up of an internal hydraulic component showing signs of wear and tear, illustrating issues related to component wear and tear in pressurised hydraulic systems. Causes include prolonged use without proper maintenance, operating beyond design specifications, inadequate lubrication, contaminated or degraded fluid, and cavitation caused by overspeed, wrong oil viscosity, and/or temperature range. Symptoms include unusually loud noises or vibrations of pumps, grinding noises in motors, slow or jerky movements of actuators, reduced overall system performance such as low torque and power, visible damage to components such as scratched rods on cylinders, and physical wear to internal components in pumps and motors.

Troubleshooting Common Hydraulic System Issues

1. Addressing Overheating

Solution:

  • Inspect Cooling Systems: Ensure that coolers and fans are clean and functioning properly. Check for adequate airflow around the system.
  • Monitor Fluid Levels: Ensure hydraulic fluid levels are within the recommended range. Top up if necessary, using the correct fluid type.
  • Check Fluid Viscosity: Verify that the hydraulic fluid viscosity matches the system requirements. Replace with appropriate fluid if necessary.
  • Reduce System Load: Avoid operating the system under excessive load for prolonged periods. Implement load management practices.
  • Run Pumps and Motors at or below manufacturers recommended maximum continuous Speed (RPM)

2. Combatting Fluid Contamination

Solution:

  • Regular Maintenance: Follow a strict maintenance schedules, this may include a combination of extended idle time and hours actually worked, Regular fluid changes and filter replacements should be irrespective of hours worked. Inspect and Replace Seals: Regularly check seals for wear and damage on cylinder rods, Motor shafts and tank cover gaskets. Replace as needed to prevent contamination ingress.
  • Proper Storage and Handling: Store hydraulic fluids in clean, sealed containers. Avoid storing containers in direct sunlight or outdoors. Use proper handling and dispensing procedures to avoid introducing contaminants.
  • Implement Filtration Systems: Use high-quality filtration systems to remove contaminants from hydraulic fluid continuously.
  • Invest in regular oil sampling and testing: This is a cost effective exercise that potentially could save you thousands of dollars and bitter disappointment. 

3. Eliminating Air Contamination

Solution:

  • Bleed the System: Properly bleed the system to remove trapped air. Follow manufacturer guidelines for bleeding procedures.
  • Check for Leaks: Inspect suction lines and connections for leaks. Look for cracked kinked or squashed hoses, and repair or replace any damaged components.
  • Maintain Fluid Levels: Ensure the reservoir is adequately filled with hydraulic fluid to prevent air ingress.
  • Replace Damaged Seals: Check and replace any worn or damaged seals that may allow air to enter the system.
  • Ensure oil return lines to the tank enter the tank below the minimum oil level (return lines must be submerged) 

4. Preventing Cavitation

Solution:

  • Maintain Adequate Fluid Levels: Ensure the system reservoir is properly filled.
  • Control Fluid Temperature: Keep hydraulic fluid within the recommended temperature range to prevent vapor bubble formation.
  • Ensure Proper Inlet Pressure: Check and maintain pump inlet pressure to avoid conditions leading to cavitation.
  • Use Correct Fluid Viscosity: Make sure the hydraulic fluid used is within the correct viscosity range specified by the manufacturer.
Close-up of a hydraulic component surface showing signs of cavitation damage, illustrating the importance of preventing cavitation in pressurized hydraulic systems. Solutions include maintaining adequate fluid levels to ensure the system reservoir is properly filled, controlling fluid temperature to keep hydraulic fluid within the recommended range and prevent vapor bubble formation, ensuring proper inlet pressure to avoid conditions leading to cavitation, and using the correct fluid viscosity as specified by the manufacturer.

Hydraulic systems are integral to many industrial applications, and maintaining their efficiency and reliability is crucial. 

5. Fixing Hydraulic Leaks

Solution:

  • Inspect Hoses and Fittings: Regularly check hoses, fittings, and connections for signs of wear, links or damage. Tighten or replace as needed.
  • Replace Worn Seals: Identify and replace any seals on adaptors, cylinders, pumps and motors that are worn, damaged, or leaking.
  • Monitor System Pressure: Ensure the system is operating within the recommended pressure range. Install pressure relief valves if necessary.
  • Perform Regular Inspections: Conduct routine inspections to identify and address leaks or wet, Dark and or Shiny patches early.

6. Mitigating Component Wear and Tear

Solution:

  • Implement Preventive Maintenance: Establish a preventive maintenance schedule to monitor and address component wear regularly.
  • Lubricate Components: Ensure all moving parts are adequately lubricated with the correct oil or grease to minimise friction and wear.
  • Use Quality Hydraulic Fluids: Use high-quality hydraulic fluids that meet system specifications to protect components and enhance performance.
  • Monitor System Performance: Keep track of system performance metrics to identify early signs of wear and address them promptly.


By understanding common hydraulic system issues and how to troubleshoot them, you can ensure your hydraulic systems operate at peak performance, minimising downtime and maintenance costs. 

Regular maintenance, proper fluid management, and timely component inspections are key to preventing issues and extending the life of your hydraulic systems. 

Whether you’re dealing with overheating, fluid contamination, entrained Air, leaks, or component wear, following the troubleshooting steps outlined in this guide will help you address these problems effectively and maintain a robust hydraulic system.