How To Check Hydraulic Fluid Level: Quick Guide

Excavators, forklifts, presses, and numerous pieces of construction equipment require specific amounts of hydraulic fluid to function. Hydraulic fluid supports several key processes in these machines, from lubricating and cooling internal components to creating a seal to pressurize the system and transmit power. 

Below, explore how to check hydraulic fluid levels quickly so you can maintain your machinery without significant downtime. 

Why Are Hydraulic Fluid Levels Important? 

Hydraulic fluid lubricates, controls temperature, seals, and transmits power within heavy-duty machinery or equipment. 

Hydraulic fluid flows through the system and lubricates and removes heat from critical internal components to maintain optimal operating conditions. Proper fluid levels also enable the system to create a tight seal, pressurize, and transmit power effectively and efficiently. 

When hydraulic fluid levels drop, the system can no longer perform as expected. A low volume of hydraulic fluid restricts the system from building the appropriate pressure to source energy and do mechanical work. 

A lack of seal can also lead to contamination, which degrades the oil and prevents it from reducing friction and heat within the system. If left unaddressed, this will eventually lead to failure. 

How To Check Hydraulic Fluid Levels

Hydraulic fluid is used in machinery in several industries, including construction and agriculture.

While the process is fairly standard across various types of equipment, it’s a good idea to check the manufacturer’s recommendations before proceeding. 

1. Check Hydraulic Levels When Equipment Is Cold

Before checking the hydraulic fluid levels in any machinery, ensure it’s turned off and cooled down enough to work on. 

Hydraulic fluid expands when it gets hot, so you’re more likely to get an inaccurate fluid level reading if you measure when the machine is operating or has just been shut down. A cool machine also removes the risk of hot hydraulic fluid coming into contact with any part of your body. 

Park the equipment on level ground before letting it cool. If the machine has an extending feature, such as a bucket, boom, or forks, these may need to rest on the ground to allow any hydraulic fluid within them to drain into the reservoir for a more accurate reading. 

Again, check the owner’s manual for specifics, as some machines’ recommended hydraulic fluid levels are measured while the machine is operating or “hot.” 

2. Clean Around the Fluid Level Checkpoint

Wipe down the area where the dipstick comes out of the machine to ensure no contaminants enter the hydraulic system. If your machine has sight glass, clear the face of the glass to view the hydraulic fluid levels properly. 

As you clear away dirt and debris, look for leaks or signs of damage, especially around hoses and fittings. 

3. Evaluate the Hydraulic Fluid Level

Remove the dipstick, wipe it clean, replace it in the machine, and remove it again to gauge the hydraulic fluid level. A sight glass simplifies the process. Simply look at the level to determine if it’s within the specified range.

4. Inspect the Fluid’s Appearance

As you visually inspect the hydraulic fluid, examine it for contaminants. Clean hydraulic fluid is typically transparent or clear, with a slight amber tint. If the fluid is black, sludgy, or smells burnt, replace it immediately. 

Burned hydraulic fluid can indicate the system is overheating during normal operations. Most hydraulic fluid operates between 120 and 150 degrees Fahrenheit, depending on the equipment. If the fluid exceeds normal operating temperatures, there may also be an issue with the unit’s cooling system. 

5. Record Your Findings

Keep a logbook detailing when you last checked the hydraulic fluid levels, what those fluid levels were, and any notes regarding the fluid’s condition. These notes can help inform future maintenance, especially if you make any repairs to the system. 

With enough time and data, you can adjust preventative maintenance schedules or even develop predictive maintenance protocols. 

What To Look For When Inspecting Hydraulic Fluid Levels

The key purpose of inspecting hydraulic fluid levels is to determine whether the fluid is viable enough to continue supporting the machine’s basic operations or if it requires replacement. The fluid’s condition also sheds light on potential underlying issues that could cause the replacement fluid to deteriorate prematurely. 

Discover what hydraulic fluid characteristics you should pay attention to below, but don’t forget to dispose of used hydraulic fluid responsibly. 

Low Fluid Levels

Low hydraulic fluid levels can lead to a loss of pressure, increased component wear, and extreme operating conditions that cause overheating. 

When the system fails to seal, contaminants are more likely to enter the system. These foreign particles alter the fluid’s chemical makeup, reducing its lubricating abilities and allowing friction to increase operating temperatures to the point where the fluid cannot adequately absorb and remove heat. 

Preventing low fluid levels begins with properly filling the reservoir at the outset. Inspect the fill cap and seal to ensure both are functional. Check fluid levels regularly and top off as needed. 

Contamination

Contaminants can easily enter the hydraulic system through worn or damaged seals, and the damage they cause is severe. Dirt, water, and debris can clog filters, valves, and lines, restricting critical flow, accelerating component wear, and degrading the machine’s overall performance. 

Regular fluid changes, filter inspections, and close monitoring can help prevent contamination within the hydraulic system. 

Degradation

Hydraulic fluid, like any other type of consumable, degrades naturally over time. However, contaminants — like debris or air that enters the hydraulic system — and excessive or extreme operating conditions can speed up the degradation process and cause a loss of viscosity, overheating, cavitation, and color changes. Degraded hydraulic fluid can appear brown or black, with foam or sludge present. 

Refilling the machine with the proper type of hydraulic fluid and changing it at the manufacturer’s recommended intervals helps ward off premature degradation. Problems with the cooling system can also influence the hydraulic system, so keep an eye on the machine’s radiator and related components. 

Avoid excessive loads, extreme temperatures, and other conditions that put undue stress on the equipment.

Best Practices for Hydraulic Fluid Maintenance 

Now that you know how to check hydraulic fluid levels, add it to your routine maintenance tasks. Address any issues you found while checking the fluid and make the necessary changes. For example, keep the system clean to prevent contaminants and ensure optimal operating temperatures to reduce overheating and degradation. 

Routine hydraulic fluid checks should also happen at regular intervals between hydraulic fluid flushes. Train staff to inspect hydraulic fluid filters with each inspection and flush. Oil analysis can also help equipment owners evaluate and adjust maintenance intervals to get the most out of hydraulic fluid changes. 

Hydraulic Maintenance Made Simple With Cadence

The experts at Cadence know that without the proper industrial oils, heavy-duty machinery can quickly become dead weight. 

Call us at 336-629-2061 to learn more about how our high-quality products support numerous businesses across industries, from the largest operations to smaller outfits. We take pride in delivering value to our customers at every turn. 

Sources:

Hydraulic Fluids | Engineering Library

Managing Used Oil: Answers to Frequent Questions for Businesses | EPA 

Hydraulic Fluid Safety | Tameson.com

Cavitation Flows | University of Minnesota Fluid Mechanics Lab