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What Causes Hydraulic Fluid to Overheat

by Dr McCaslin | Oct 11, 2018 |

Hydraulics, hydraulic fluid


Hot hydraulic fluid can be one of the causes of an overheating final drive motor. If your hydraulic fluid is running at a higher than normal temperature then it can cause problems for your entire hydraulic system. In this Shop Talk Blog post, we are going to talk about what can cause hydraulic fluid to overheat.

What Causes Hydraulic Fluid to Overheat

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Hot Hydraulic Fluid

So, what is hot? Most experts agree that an operating temperature above 180°F is too hot for hydraulic fluid. Temperatures this high will cause the hydraulic fluid to age and degrade far more quickly. Temperature also affects the viscosity of the fluid. Higher temperatures reduce viscosity, which can negatively impact the ability of hydraulic fluid to transfer power. Hydraulic hoses and seals can also be damaged over time by hot hydraulic fluid. All of this combined will significantly affect the performance and efficiency of your system, besides causing additional problems that can become costly to repair.

Changing the System Pressure

One thing that is sure to mess up your hydraulic system is to decide to change the system pressure from what the manufacturer has it set at. Adjusting the system pressure will result in overheating, among other things. The system pressure was determined by engineers who put a good deal of effort into designing your machine, and they did not arbitrarily choose what the system pressure should be.




Relief Valve Out of Adjustment

Another potential source of problems is a relief valve. If a relief valve fails or is out of adjustment, it can affect the system pressure. Changes in system pressure, as we just discussed, can also affect the temperature of the hydraulic fluid.

Wrong Type of Hydraulic Fluid

If you use the wrong type of hydraulic fluid for your machine, that, too, can cause the fluid to overheat. If that’s the case, then you need to replace the hydraulic fluid to fully address the problem.

Oil Cooler Problems

If the oil cooler gets dirty or becomes plugged, that can also cause hydraulic fluid to run too hot. The solution to this problem is to take some time to clean off the oil cooler fins. Another potential source of problems is the cooling fan. If it is damaged, or if the fan belt isn’t at a right tension, then it can be the source of hot hydraulic fluid.

Low Hydraulic Fluid Level

Another source of overheating lies in the level of your hydraulic fluid. If your reservoir is low on hydraulic fluid, that can cause the fluid that is in the system to overheat. However, that points to another problem: a leak somewhere. Don’t just top off the hydraulic fluid level, but also check for leaks that could be responsible for a low level of fluid.





If your hydraulic system is running too hot, then you need to track down the source of the problem. Hot hydraulic fluid will lead to damage and is a sign that something is wrong and needs to be addressed. If left unaddressed, then expensive issues and unnecessary downtime are bound to be the results.

Texas Final Drive is your partner in providing new or remanufactured final drive hydraulic motors from a single mini-excavator to a fleet of heavy equipment. Call today so we can find the right final drive or hydraulic component for you, or check out our online store to find your O.E.M. manufacturer brand motor now. 

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Topics: Hydraulics, hydraulic fluid

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