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Hydraulic System Problems And Solutions

Hydraulic systems are specifically designed to facilitate certain movements, such as lifting, pulling and pushing – and these systems serve as the core of all productivity in the workplace/worksite. This is why when hydraulic system problems occur, the efficiency can slow by huge degrees, costing the business dearly. If you see symptoms that indicate that your hydraulic system is unhealthy, it’s important to discontinue use, as the damage will only spread. 

The heart of a hydraulic system is the pump, which is fitting, as it serves a similar function. Like how the heart pumps blood, the hydraulic pump pumps hydraulic fluids, which transmit energy and lubricate components. It’s here, however, where 80-90% of hydraulic system problems happen. Water and air contamination of the fluid results in poor hydraulic performance.

The following is a breakdown of the various system problems, what their causes are, and the best solutions for them.

Hydraulic Systems’ Temperature Increase

At peak efficiency, hydraulic system temperatures should be around two degrees Celsius. You should be able to monitor your system’s temperature through a gauge, though this depends on the hydraulic machine itself. Some hydraulic machines even come with a fluid temperature alarm, allowing you to identify issues before they manifest in the form of lowered productivity.

Excessive heat can have massive consequences on a hydraulic system:

  • Fluid Degradation – Fluid can break down at a foundational level, and lose its lubricating properties. Proper lubrication is necessary for movement throughout the system, and losing it means it’s less effective at transferring power from one end to the other.
  • Seal Damage – Over time, seals become brittle and begin to crack as a result of the heat. This, in turn, causes leaks. Leaks will render the entire machine inoperable.
  • Component Wear – Friction from wear and tear on moving parts, such as variable displacement pumps and pressure relief valves, accelerates dramatically without the lubrication properties of the fluid. This leads to grinding, reduced efficacy, and eventual internal leakage.
  • Oxidation – Fluid becomes infused with oxygen, which then forms sludge and varnishes that clog filters and restrict fluid flow.
  • Reduced Efficacy – The system’s overall performance will begin to suffer quickly and noticeably. Slow or erratic operation will make work unproductive, and sometimes even dangerous.

Causes And Solutions For High Temperatures

  1. Air Contamination – Trapped air can cause hydraulic fluid temperatures to skyrocket due to the constant compressing and decompressing of the air bubbles which form. This will manifest through erratic actuator movement, spongy operation and increased noise levels.
    • Bleed The System – Follow the manufacturer’s recommendations for bleeding the system to remove trapped air bubbles. This almost always involves opening a bleed valve at the highest point in the system.
  2. Low Fluid Levels – Low fluid levels restrict the system’s ability to dissipate heat, causing the pump to work harder. This is an easy cause to identify, as your hydraulic machine will have some mechanism by which you can check the fluid levels.
    • Maintain Correct Fluid Level – Make it a habit to check the fluid levels. It’s important to check for leaks or other faults that can diminish fluid if it’s excessively low, but if it’s below optimal efficiency levels, top up the system with the same type and grade of hydraulic fluid.
  3. Dirty Filters – If the filtration system is clogged, fluid flow will be restricted and the pump will overwork and generate excessive heat. Monitor your hydraulic machine’s pressure gauges. The difference between the clean filters’ pressure gauges should be minimal, but if it’s high, then this indicates a dirty filter.
    • Ensure Proper Filtration – Filters are made to be replaceable, and as such, we’d recommend following manufacturer recommendations. If compatible, consider buying a higher-quality filter that is designed to be compatible with the system.
  4. Worn Or Damaged Pump – The pump is the heart of hydraulic systems, and when it’s worn or damaged, the entire machine is in jeopardy. As far as temperature changes go, a worn pump can create friction, leading to elevated temperatures and excessive heat. Listen for knocking noises, or vibrations coming from the area in which the pump is situated to determine whether or not this is the cause.
    • Pump Repair – In the event of a broken pump, the only solution is to replace or repair the pump. Our hydraulic repairs come with a free, no-obligation diagnostic. We come out to collect the components and begin work immediately at our state-of-the-art workshop.
  5. Heat Exchanger – A faulty heat exchanger is either clogged with debris or contaminates, or damaged through malfunctioning components or an internal leak – making it hard for the machine to dissipate heat effectively. Check the temperature of your fluid as it enters and exits the heat exchanger.
    • Clean or Repair – A heat exchanger can either be too dirty to work effectively, in which cleaning it as soon as the problem arises is the solution, or it can be too damaged to be rectified.
  6. Overloaded System – When a system’s overloaded, it works beyond its intended limitations, and therefore creates excessive wear and stress on components, increasing the temperature of the system. There are multiple symptoms of an overworked system, such as sluggish operation, decreased hydraulic power, overheating and groaning/whining noises.
    • Adjust – An overloaded system is not a broken system. Consider adjusting the relief valve or modifying operation cycle to reduce the load on the system. Alternatively, reduce the external load of whatever the system is lifting or moving.
  7. Internal Leaks – Internal leaks can be hard to detect, as there are many paths that hydraulic fluid takes throughout the system. When a leak happens, the gap or seal in which the fluid leaks from increases in heat as the fluid pushes through the gaps and friction occurs.
    • Diagnostics – Due to internal leaks being hard to identify, it’s recommended that you have an expert diagnose your system. The possible replacements of your system could be the seals, O-rings, entire valves or actuators etc.

Hydraulic System

Excessive Noise

Hydraulic machines are noisy by nature, but when the noise goes past what’s normally standard, it’s likely there’s an issue with the interior system. As always, swift action will always result in a smaller repair bill, as there is a lot of interconnectivity in a hydraulic system, ensuring that the damage will spread.

Ignoring excessive noise will result in:

  • Component Damage – Excessive noise indicates friction, vibration and stress within the system. This will spread to components, which will then become damaged.
  • Efficiency Decrease – As the noise continues, you will notice the efficiency of your hydraulic system decrease. This is due to the damage spreading.
  • Increased Energy Consumption – When components require more energy as a result of damage, it will draw more energy to try and achieve its original efficiency.
  • Safety Hazard – Catastrophic failures within a hydraulic system can result in harm to a person, such as a bursting hose whipping with pressure.

Causes And Solutions For Excessive Noise

  1. Air within the System (Aeration) – Air bubbles can get trapped within hydraulic fluid, causing knocking noises as they compress and decompress. Check for cloudy or foaming hydraulic fluid in the reservoir, watch for spongy or erratic actuator movement and listen for the hammering which should change with varying system pressure.
    • Adjust Hydraulic Fluid – Bleed the system according to the manufacturer instructions. This will remove trapped air. Then check for leaks, thoroughly inspecting the suction lines, fittings and seals. If any damage is detected, you will need to have a professional replace or repair them. Lastly, ensure that the fluid level in the reservoir is within suitable range.
  2. Cavitation – Caused when pressure within hydraulic fluid drops below vapour pressure. Bubbles will then form and collapse, creating high-pitched whining or screeching. In events of cavitation, it’s best to act immediately, as the pump components will become damaged – and they are the heart of the system.
    • Cleansing or Repair – Firstly, ensure fluid levels are maintained to ensure adequate pump inlet pressure. If the problem persists, you may need to clean the pump inlet strainer to prevent clogs. If you notice damage with the pump, then it will require repairing.
  3. Worn or Damaged Pump – As pumps age, or experience wear and tear, the bearings, vanes, and gears can become damaged/misaligned. The noises that result are grinding, growling or whining noises.
    • Replacement or Repair – Worn/damaged components within the pump can be repaired, but it is much more cost-effective and guaranteed to replace them. However, if the seals of the pump are worn, the seals can be replaced to restore full function.
  4. Mechanical Vibration – Loose mounting bolts, worn bearings or misaligned components within the motor can cause components that should otherwise be apart to move and vibrate against each other.
    • Component Security – Loose mounting bolts can be tightened using a torque wrench. However, if the bearings are worn, they must be replaced and lubricated. Misaligned components should be realigned according to manufacturer’s instructions, though it may be better to find a qualified hydraulic repairman to do this.
  5. Fluid-Borne Noise – Hydraulic fluid experiencing faults can also generate noise, such as hissing, whistling or rushing. It can be caused by a few different issues, such as turbulent flow, high fluid velocity, valve issues or hydraulic shock.
    • Full Diagnostic – The truth is, there are so many different problems that the solutions are hard to recommend without knowing the specific one. Eliminating restrictions, reducing fluid velocity, repairing/replacing valves, dampening hydraulic shock or even redesigning the system may be necessary.

Abnormal Fluid Conditions

Finally, the hydraulic fluid within the system could take on several states that will damage the system overall. Deviations essentially change the property of the hydraulic fluid to no longer be suitable for the system, and the longer it remains in the system, the more damage over time.

Causes And Solutions For Abnormal Fluid

  1. Contamination – Foreign substances that enter the system somehow, and end up in the hydraulic fluids, can result in the system’s components becoming damaged. Fluid becoming cloudy, discoloured or even having visible particles are telltale signs of this.
    • Cleansing – Poor filtering may be the cause, so check your filters and replace if they’re due, and check seals to ensure all are tight. If you find the contamination to be severe, it’s best to flush and replace all hydraulic fluid within the system. Ensure all containers for hydraulic fluid are clean, and hydraulic equipment used to interact are similarly so.
  2. Degradation – Hydraulic fluid degradation can result due to oxidation, thermal stress and chemical reactions with contaminants. This will manifest in the fluid darkening, letting off a burning odour, or becoming thick/thin.
    • Replace and Control – Replace the degraded liquid with high quality fluid. Afterwards, ensure contamination is controlled through regular system maintenance, and operate your machine within recommended temperature ranges.
  3. Foaming – When air becomes trapped within the hydraulic fluid, it will create a frothy/bubbling appearance. This at least makes it easy to diagnose.
    • Repair and Adjust – Using anti-foam additives within the fluid will reduce the risk of foaming via aeration. If your pump is working too hard, adjust its speed, and repair any leaks that you find within the system – as always, a professional may be best placed to help here.


This collection of common hydraulic system problems and solutions are the tip of the iceberg, and by no means cover all possible hydraulic problems. CJ Plant recommends consulting with professionals if your system has suffered too much damage. Our diagnosis is fast and free, and our repair work is second to none. 

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