If you own an excavator, proper maintenance can maximize its lifespan. One of the recommended maintenance methods is to regularly check the fluid levels, especially the hydraulic oil. Hydraulic oil powers all hydraulic operations, from digging and lifting to attaching various tools. Maintaining optimal hydraulic oil levels ensures smooth operation of your mini excavator.
This article will provide a clear guide to checking hydraulic oil levels, including pre-inspection preparation, standard operating procedures, and more.
Safety Inspection and Preparatory Work
Before officially starting the hydraulic oil level inspection, you must ensure that the operating environment and equipment status are in safe and stable conditions. Many times, the problem with incorrect inspection methods lies not in the steps themselves, but in the preparation. To avoid misreading the liquid level or potential risks, you need to complete the necessary safety checks and preparations before operating.
Security Measures
- Park the excavator on a flat, firm, level surface.
If the excavator is parked on a slope, the hydraulic oil in the tank will be unevenly distributed, causing inaccurate oil level readings. It’s recommended to park the excavator on compacted concrete or hard-packed dirt, rather than soft soil, slopes, or potholes.
- Fully lower all working devices (bucket, boom, and shovel) to the ground.
If the boom or bucket is not lowered, it may drop unexpectedly due to residual pressure in the hydraulic system. Moreover, after the working device is completely landed, the hydraulic oil can flow back to the oil tank. Oil retention in the lines may cause the oil level in the tank to be falsely low, affecting the accuracy of the reading.
- Turn off the engine and remove the key for safekeeping.
This prevents accidental starting of the equipment. Even if you temporarily leave the inspection location, leaving the key in the ignition could cause the engine to start by accidentally touching the lever or someone else’s mistake.
- Allow the hydraulic oil to cool before operating to avoid burns from hot oil splashing.
After operating the excavator, the hydraulic oil temperature may reach 60-80°C. If you open the oil level inspection cover or fuel tank cap at this time, the high-temperature oil may splash out due to pressure and burn your hands, face, and other parts of your body. It is recommended to wait for 15-30 minutes after stopping the machine (the specific time can be adjusted according to the ambient temperature) and wait until the oil temperature drops below 40℃ (the outer wall of the oil tank should not be hot to the touch) before operating.
- Wear appropriate personal protective equipment (PPE), such as gloves and safety glasses.
During the inspection, you may come into contact with oil stains or metal parts or be exposed to the risk of oil splashes. Gloves can protect your hands from oil stains and scratches from parts. Safety glasses can prevent oil and dust from splashing into the eyes.
Required Tools and Items
After confirming the safety measures, preparing the appropriate tools and supplies will ensure a smooth hydraulic oil level check. Therefore, you need to prepare the following items in advance and confirm their status.
First you need to prepare a clean cotton or lint-free cloth. This type of cloth can clean oil and dust from the surface of the oil level gauge. When opening the fuel filler cap, you can wipe off any debris around the cap to prevent it from falling into the fuel tank and contaminating the oil. If you use old towels, ordinary rags, and other lint-shedding materials, the lint can easily enter the fuel tank during operation, thereby clogging the hydraulic pipeline or wearing out the hydraulic pump.
Secondly, gloves must provide both cleanliness and protection. They prevent hand sweat, dust, and oil from coming into direct contact with the oil level gauge and filler cap, preventing impurities from entering the fluid. They also provide a non-slip and scratch-resistant surface when opening the oil cap and touching the outside of the tank. It is recommended to give priority to nitrile gloves that are wear-resistant and not easy to absorb oil, rather than cotton gloves that are easy to absorb oil and difficult to clean.
Additionally, you should prepare appropriate containers if necessary. This type of container is only used in specific scenarios. For example, when the oil level is found to be too high and excess oil needs to be drained, or when the oil level is too low and new oil needs to be added, the container needs to be cleaned and dried in advance to avoid residual moisture and impurities contaminating the oil. The capacity can be selected into a 5-10L bucket according to the specifications of the excavator’s fuel tank. This prevents oil spills when pouring and facilitates the subsequent disposal of excess oil in accordance with environmental protection requirements.
Finally, you’ll need tools such as wrenches to open the fuel filler cap, depending on the model. Not all models require this tool. Some excavators have a manually unscrewed oil level inspection cap that requires no additional tools. However, the fuel filler caps on some heavy-duty models or older equipment may become rusted, screwed shut, or have bolts securing them due to long-term use. At this time, you need to prepare open-end wrenches and ring wrenches of matching specifications. Be careful to avoid using an adjustable wrench, as it can slip and damage the cover threads. It’s recommended to confirm the fuel filler cap structure of your model in advance to avoid delays due to missing tools.
Looking for a Hydraulic Reservoir and Dipstick/Oil Level Gauge
You’ll need to locate the hydraulic oil tank and an indicator for reading the oil level. The location of the hydraulic oil tank is usually fixed. Most excavators place it behind the counterweight or on the side of the fuselage for easy refueling and inspection. The specific location can be confirmed according to the equipment manual or model identification.
There are two common oil level indicators:
Dipstick: This is the most common way to check the oil level; it is typically attached to the hydraulic oil filler cap. You can determine the hydraulic oil level by removing the dipstick, wiping it clean, reinserting it, and reading the scale.
Sight Glass: Some excavators have a transparent, round or strip-shaped window mounted on the side of the oil tank. You can quickly determine whether the oil level is within the normal range simply by observing it directly from the outside.
Method 1. Using the Dipstick to Check Hydraulic Oil Level
Using the dipstick is the most common and intuitive way to check the hydraulic oil level. During operation, it is necessary to judge separately according to the cold and hot car states to ensure accurate readings.
Before opening the fuel tank cap, thoroughly clean the dust and debris around the fuel filler port with a clean cloth to prevent impurities from falling into the hydraulic system.
Cold Engine Check (Static Oil Level): Turn off the engine and let it sit for at least 30 minutes to allow the hydraulic oil to drain back into the tank. The oil level should remain between the MIN and MAX marks on the dipstick.
Warm Engine Check (Dynamic Oil Level): Start the engine and operate all equipment for 5–10 minutes to allow the hydraulic oil to reach normal operating temperature. Then, immediately turn off the engine and check the dipstick. The liquid level at this time is usually closer to the MAX line, which better reflects the oil level status of the equipment under actual working conditions.
After pulling out the dipstick, wipe it clean with a clean cloth, then fully insert it, then pull it out again, observe the position of the oil on the dipstick, and record the reading.
Method 2. Using the Sight Glass for Inspection
In addition to the oil dipstick, some excavators are equipped with an oil sight glass, which allows you to observe the hydraulic oil level more intuitively.
Before inspection, wipe the surface of the oil sight glass with a clean cloth to ensure that there is no dust, oil, or water vapor blocking the observation.
Observe the oil level with the engine either cold or hot, as directed by the manual. The hydraulic oil level should be maintained between the upper and lower scale lines on the sight glass, with the ideal position usually close to the middle.
If the level is too low, replenish the hydraulic oil promptly. If it is too high, it may need to be drained. If you find that the oil sight glass is blurred due to long-term oil pollution, you should consider further cleaning or replacing it to avoid affecting your judgment.
Conclusion
Regular inspections can effectively prevent hydraulic component wear, operational stalls, and other problems caused by abnormal oil levels and can also reduce equipment downtime and maintenance costs.
However, in actual operation, the hydraulic system layout and oil level detection component characteristics of different models of excavators may be different. Some equipment may also experience issues such as aging detection components and oil obstruction due to long-term use.
If you have professional technical support, it can solve a lot of troubles. Evisco has experience adapting to various machine models. We can answer your practical questions about oil level checks and provide maintenance solutions tailored to your equipment needs. If you have any questions regarding excavator hydraulic system maintenance, please feel free to contact Evisco.
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