Hydraulic Cylinder Failure: The Dieseling Effect Causes and Prevention Measures

1 August 2016
 Categories: , Blog


Without the proper performance of hydraulic cylinders, many construction equipment and manufacturing machinery would not be able to operate efficiently. If you run any hydraulic equipment, you may be aware of the different problems that can cause cylinder failure. One of these is the dieseling effect. The dieseling effect occurs when excess air is drawn into the hydraulic cylinder and mixes with the hydraulic oil. When the oil is pressurized, it explodes due to the high volume of air in it.

Causes of dieseling effect

Note that hydraulic cylinder oil usually contains some amount of air. The air molecules attach themselves to the oil molecules in a process known as saturation. When saturation occurs, the presence of air in the oil does not affect the performance of the hydraulic cylinder. However, if the amount of air is directly proportional to the pressure exerted on the oil by the hydraulic pump, higher amounts of air will mix with the oil causing the dieseling effect.

There are two common causes of the dieseling effect in hydraulic cylinders:

  • Incorrect commissioning and re-commissioning procedures during startup and after carrying out maintenance work. Faulty components that are not checked before start-up can cause air to mix with the hydraulic fluid and explode.
  • Incorrectly adjusted or faulty load control valve, causing the fluid demand in the cylinder to exceed the volume of hydraulic fluid that's pumped into the cylinder. This causes negative pressure to build on the cylinder rod and allows excess air to be drawn past the rod seals.

Effects of dieseling effect

The dieseling effect can cause the cylinder components in the hydraulic equipment to lose lubrication or overheat. Components end up wearing out fast and eventually fail, affecting the performance of the entire hydraulic system. Some cylinder parts such as seals are affected by high temperatures; therefore, when they overheat, they will be damaged over time.

How to prevent dieseling effect

Here are some of the measures you can take to avoid the dieseling effect and subsequent damage of your hydraulic equipment:

  • Manually bleed the hydraulic system during installation or install an automatic bleeder device to get rid of excess air that can cause an explosion in the system.
  • Inspect cylinder components through scheduled maintenance and before commencing operations to ensure all parts are in proper physical condition.
  • During commissioning, stroke the cylinder several times without load to purge air out of the cylinder.
  • In the case of cylinder failure, always inspect it for dieseling problems before ruling it out and moving on to other causes of cylinder failure.

Cylinder failure can cause downtime and frustrate operations in the industry. Carrying out regular maintenance of hydraulic equipment can help prevent dieseling effect and other causes of cylinder failure.