Hydraulic System Slowing Down When Warm: Causes and Solutions

[MikePhua]

Hydraulic systems are critical components in heavy equipment, including excavators, loaders, and other construction machinery. These systems are responsible for providing the power necessary to perform a variety of tasks such as lifting, digging, and moving heavy loads. However, one common issue that operators may encounter is the slowing down of hydraulics once the equipment warms up. When the hydraulic system starts out strong but becomes painfully slow after a while, it can affect the machine’s performance, causing delays and even potential damage if left unresolved. Understanding the causes of this issue and knowing how to address it can help ensure that your hydraulic system operates smoothly under all conditions.
Understanding Hydraulic Systems in Heavy Equipment
Hydraulic systems use pressurized fluid to transfer energy and perform various mechanical tasks. These systems consist of a hydraulic pump, valves, hoses, cylinders, and fluid. The pump generates pressure by pushing hydraulic fluid through the system, which in turn drives the movement of machinery components like booms, arms, and buckets.
The efficiency of the hydraulic system depends on factors such as fluid viscosity, pump efficiency, and the condition of seals and valves. However, like any other component of the equipment, the hydraulic system can experience performance issues, especially as the equipment undergoes heavy use over time.
What Happens When Hydraulics Slow Down?
When the hydraulics of a machine get “painfully slow” after warming up, operators may notice that the response time for hydraulic movements increases. For example, when operating the boom, bucket, or other hydraulic functions, the machine may take longer to respond or may not reach full speed. This slowdown can be accompanied by a decrease in power, especially during demanding operations.
This issue can occur for a variety of reasons, and understanding the root cause is crucial to diagnosing and fixing it effectively.
Common Causes of Slow Hydraulics When Warm

1. Hydraulic Fluid Viscosity Issues:
   One of the primary reasons for a hydraulic system becoming sluggish as it warms up is the viscosity of the hydraulic fluid. Hydraulic fluid is designed to operate efficiently within a certain temperature range. As the fluid warms up, its viscosity (or thickness) decreases. If the fluid becomes too thin, it may not provide the necessary pressure to keep the system running at optimal speed. Conversely, if the fluid is too thick when cold, it can cause strain on the pump until it reaches an optimal operating temperature.
   Solution: Check the fluid type and make sure it is rated for the temperatures in which the machine is operating. If the machine operates in extreme temperature conditions, using a multi-viscosity fluid may help maintain proper viscosity levels.
   
2. Contaminated or Degraded Hydraulic Fluid:
   Over time, hydraulic fluid can become contaminated with dirt, moisture, or metallic particles from wear and tear. Contaminated fluid can cause clogging in the hydraulic filters, leading to slow operation, especially once the fluid has warmed up. In some cases, moisture in the fluid can cause foaming, which will reduce the efficiency of the hydraulic pump.
   Solution: Regularly replace the hydraulic fluid as per the manufacturer’s guidelines. Ensure that filters are changed regularly to prevent buildup of contaminants. A filtration system designed to remove particles before they enter the pump can also be beneficial.
   
3. Damaged or Worn Hydraulic Pump:
   The hydraulic pump is the heart of the system. It is responsible for maintaining the flow of fluid under pressure. If the pump is worn out, the pressure will drop, leading to slower operation. This can become more noticeable when the system heats up because the fluid expands, and the pump’s ability to maintain pressure diminishes.
   Solution: Inspect the hydraulic pump for any signs of wear or damage. If the pump is not functioning correctly, it may need to be rebuilt or replaced. Regularly servicing the pump can extend its lifespan and prevent unexpected breakdowns.
   
4. Faulty Valves or Pressure Relief Valve Malfunction:
   Hydraulic valves direct fluid flow to different parts of the system. If any of the valves are malfunctioning or clogged, it can result in erratic fluid flow, which causes slow operation. The pressure relief valve, in particular, is a critical component, as it maintains the pressure within the system. A stuck or malfunctioning pressure relief valve can cause the system to lose pressure, slowing down hydraulic movements.
   Solution: Check all valves for proper functioning. If necessary, clean the valves or replace damaged ones. Ensure that the pressure relief valve is calibrated and working properly to avoid unwanted pressure drops.
   
5. Leaks in the System:
   Leaks in the hydraulic lines, seals, or fittings can lead to a loss of fluid and pressure, which can slow down the system. As the system warms up, the material may expand, causing previously minor leaks to worsen. If a leak is present, the hydraulic fluid can escape, reducing the fluid’s volume and causing a drop in system pressure.
   Solution: Inspect the hydraulic system for leaks, paying close attention to the seals, hoses, and connections. Replace damaged seals and tighten any loose connections. Keep an eye on fluid levels and ensure the system is fully pressurized.
   
6. Overheating of the Hydraulic System:
   Hydraulic fluid temperature plays a significant role in the performance of the system. If the hydraulic system is overheating, the fluid can break down and lose its effectiveness, leading to slower operation. This could be a result of a clogged radiator or improper cooling, especially after the system has been in use for extended periods.
   Solution: Ensure the hydraulic cooling system (including the radiator) is clean and functioning properly. If necessary, flush the cooling system to remove any dirt or debris that could impede airflow. Monitor the hydraulic fluid temperature regularly to ensure it stays within the recommended range.
   

Preventative Measures and Regular Maintenance
To prevent hydraulic systems from slowing down when warmed up, it is essential to follow a proactive maintenance routine. Some of the key preventative measures include:

• Regular Fluid Changes: Change the hydraulic fluid at regular intervals as recommended by the manufacturer. Use the appropriate type of fluid for the working conditions.
  
• Filter Maintenance: Clean or replace hydraulic filters regularly to prevent contaminants from entering the system.
  
• Pressure Checks: Regularly test the hydraulic system's pressure to ensure that it is within the recommended range.
  
• Routine Inspections: Regularly inspect the hydraulic pump, hoses, seals, and valves for wear and tear. Timely repairs can prevent more serious issues down the road.
  

Conclusion
When hydraulics get painfully slow after warming up, it’s a sign that something in the system is not functioning as it should. Whether it’s due to fluid viscosity issues, pump wear, or leaks, identifying and addressing the underlying cause is essential for maintaining optimal performance. Regular maintenance, fluid checks, and inspections are the best way to keep hydraulic systems operating smoothly and efficiently, ensuring your machinery performs at its best and avoids costly repairs.