Hydraulic oil overheating is a common fault in hydraulic systems; it has both obvious and indirect signs, frequent causes, and requires a step-by-step diagnostic process; ignoring the problem leads to costly repairs, whilst preventative maintenance extends the service life by a factor of 2–3.
Hydraulic oil overheating is a common fault in hydraulic systems, which serves as a warning sign of underlying problems in the equipment’s operation; ignoring this can lead to rapid wear and tear of components and costly repairs. Diagnosing this problem requires a systematic approach aimed at identifying the root causes of the abnormal rise in the working fluid’s temperature.
Clear signs include the operating temperature exceeding 80 degrees Celsius, the oil turning a dark brown colour, the presence of a burnt smell, as well as an increase in the fluid’s viscosity and the appearance of fine carbon particles within it. Indirect signs include a reduction in the power output of hydraulic equipment and erratic operation of the actuators.
The most common causes include a fault with the hydraulic cooler, such as a dirty radiator or a fan failure, insufficient oil level, excessive load on the hydraulic system beyond its design parameters, as well as clogged filters, which lead to increased hydraulic resistance and the generation of excess heat.
In the first stage, the actual oil temperature is measured using a contact thermometer, and the cooling system’s performance, the level and external condition of the coolant, and the integrity of the filter elements are checked. These simple steps make it possible to identify up to 60 per cent of common causes of overheating without dismantling the equipment.
If a visual inspection yields no results, a sample of the oil is taken for laboratory analysis, which determines changes in viscosity, the acid number, and the presence of wear particles and oxidation products in the fluid. Based on the results of the analysis, it is possible to determine precisely how long the oil has been operating in an overheated state and which components of the hydraulic system have already deteriorated.
When operating continuously at temperatures above 90 degrees, the oil loses its lubricating properties within 500 operating hours, leading to rapid wear of pumps, hydraulic motors and directional control valves. In extreme cases, overheating causes blockages in the hydraulic system’s passages and complete equipment failure, the cost of repairing which is 10–15 times higher than the cost of timely diagnostics.
To prevent overheating, it is sufficient to clean the radiator every 1,000 hours of operation, change the filters in accordance with the maintenance schedule, check the oil level and avoid running the equipment at maximum load for prolonged periods. Regular monitoring of the temperature regime extends the service life of the hydraulic system by a factor of 2–3 without any additional capital expenditure.
