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Hydraulic System Problems And Solutions

In any business that relies on hydraulic machinery the hydraulic systems themselves are essentially the heart of the business. If they are not functioning at peak efficiency this can slow work and cost the business dearly in wasted time and more importantly actual revenue. More importantly, if the symptoms of a damaged or poorly working system are not recognised this can result in unnecessary wear and tear on the equipment or eventually a complete breakdown bringing work to a halt and resulting in costly repairs. However, with a little care and attention from the operator, this is easily avoided. 

At the heart of the system is the hydraulic pump itself and this must be properly lubricated to perform properly. In fact, recent industry analysis has shown that contamination of the lubricating fluid is responsible for 80- 90% of hydraulic problems. Regular checks of hydraulic equipment and hydraulic testing should be a part of basic plant maintenance for all firms. An awareness of the warning signs of common hydraulic problems can save on costly plant machine repairs by dealing with problems as soon as they arise. 

Hydraulic System problems

Warning signs 

  • Increased level of temperature:

    The optimum temperature for a hydraulic system running at peak efficiency is eighty-two degrees Celsius. If your system is exceeding this temperature on a regular basis it can be a sign of aeration, a damaged heat exchanger or a build-up of debris in the filter. Increased heat in the system can cause lowered viscosity of the hydraulic fluid, reducing the lubrication of moving parts and causing them to grind against each other. This can cause wear on the parts and introduce metal fragments into the system causing internal damage and wear on seals due to the abrasive nature of the fragments. Further increases in temperature can cause the fluid to oxidise and thicken, causing a varnish-like deposit to form on components, reducing flow in the future. Higher viscosity also reduces lubrication and the ability of the fluid to cool the system. Elevated heat levels can also put unnecessary strain on the motor and cause physical degradation of seals by burning to lead to leaks and potentially allowing air to enter the system. 

  • Excessive noise:

    While hydraulics by their very nature create noise, any persistent banging or knocking sounds coming from the system can be a sign that air has entered the system (known as aeration) and contaminated the hydraulic fluid which can be responsible for a host of problems. As it passes through the system the movement of the pump causes the air bubbles to compress and decompress, causing banging or knocking sounds. When placed under pressure the air bubbles can implode which can cause wear on parts and dislodge debris, further contaminating the fluid and also raising the temperature in the pump. Unusual banging or knocking can also also be an indication of a condition known as cavitation where air or fluid vapour occupies part of the hydraulic pump rather than just hydraulic fluid. Again, the high pressure of the pump can cause this to implode and the larger volume can cause far more severe damage such as sharing of drive shafts or mechanical failure in other parts of the system. 

  • Physical condition of hydraulic fluid:

    If the hydraulic fluid is regularly drained and replaced, several signs of internal problems can also be spotted simply by observing the physical condition of the fluid itself. The temperature can easily be measured to make sure it is not above eighty-two degrees, any cloudiness due to contamination by foreign particles or air or larger particles in the fluid will be easily observed and the viscosity can be measured as overly thick fluid can be a contributing factor to cavitation. The volume of liquid in the system can also be measured, a lower volume than usual being a potential indicator of cavitation. If the fluid has a milky appearance it is a sign of water contamination which can cause reduced lubrication and corrosion due to rust, which can cause wear on parts or seizing parts which could break as a result and place extra strain on the whole system. In very cold conditions any water in the system can freeze, reducing performance and causing further damage. Foaming in the fluid is another symptom of aeration. 

  • Erratic performance:

    any erratic or slow performance can be a sign of an internal or external leak in the system. This can lead to slower cycle time and an increase in heat in the system due to dropping pressure which will lower the viscosity of the hydraulic fluid, causing an increase in leakage which in turn leads to a further increase in temperature in a vicious cycle. Erratic actuator movement can also be an indication of aeration. 


The simplest solution to all of these problems is to have your hydraulic systems regularly inspected by a professional and make sure they are regularly cleaned and maintained properly.  Prevention is always better than cure especially when your business relies upon it. However, problems can still arise unexpectedly and in this case, immediate action should be taken. 

An increase in heat can be monitored externally with an infra red thermometer but this is not always a good indicator of abnormal internal temperature. The simplest solution is to make sure a fluid temperature alarm is fitted to the system which will indicate immediately if a rise in temperature occurs. If an internal leak is suspected a hydraulic flow tester may be necessary to pinpoint the exact location, saving time and effort without the need to dismantle the entire system to find the source of the leak. External leaks, for example from a burst pipe or loose seal will often be obvious from even a cursory external examination of the equipment but it is always worth double checking that all clamps and fittings are tightly secured and seals are not brittle or worn. This is also one way to ensure no air is entering as fluid escapes, leading to aeration or cavitation. 

As the main method of heat dissipation in hydraulic systems is via the reservoir it is important to check the water level is always correct and there are no obstructions or debris that could limit airflow. The heat exchanger should also be regularly checked to ensure there are no obstructions in the core that could reduce the flow of hydraulic fluid or water through it, causing heat to build up. Obviously, if either of these parts are damaged, they should be replaced immediately. 

The pump inlet should be checked regularly as this is one of the main causes of air entering the system. All intake pipe fittings should be checked and tightened if necessary. Flexible intake pipes can also become worn or porous over time as the material degrades so these should be inspected and replaced as necessary. Lowered water levels in the reservoir can also create a vortex that allows air to enter so the water level must be kept correct. Any way air can enter is also an opportunity for water moisture to enter so it is doubly important these checks are made. In some systems, there is also a risk of air entering via the pump seal, so it is important to check this as well. 

Regularly draining and replacing hydraulic fluid is a must to ensure optimum performance. As noted above this is a perfect opportunity to inspect the fluid for any sign of contamination, whether by air, water or other foreign materials and spot any signs of heat damage or damage to the filtration system. This can give warning of many problems before they can cause physical problems with the systems and gives an opportunity to drain any water that has become trapped. Many synthetic oils for hydraulic systems are available that offer increased resistance to heat and cold, protecting the system from damage whilst reducing degradation to the oil from heat. Many also have oxidation inhibitors, anti-wear additives and anti-foaming agents to aid in extracting air from the oil, all of which can reduce the need for hydraulic pump repairs. 

At CJ Plant, we are specialists in the repair, rebuilding and maintenance of all hydraulic motors and systems and can help with any issues you may have with your equipment. We offer a fast and free UK wide collection service. We will then transport your equipment to our workshop where we will quickly assess the problem with our custom built hydraulic testing equipment and provide you with a report and no obligation quote for repair. We also offer a replacement parts service and can even provide new and reconditioned equipment should yours be beyond repair. Please contact our expert staff who will be happy to help with your queries on all types of plant maintenance. 


Telephone: 01527870793

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