Why Is My Hydraulic Motor Not Working? Causes and Solutions

A hydraulic motor is a critical component in many hydraulic systems. However, some users may find that their brand-new motor fails to operate, and they mistakenly assume the product is defective, even requesting returns. In reality, a non-functioning hydraulic motor can result from various system-related issues—not necessarily a faulty product.

This article will explore the most common reasons why a hydraulic motor won’t rotate and provide practical troubleshooting steps.

1. Insufficient System Pressure – The Root Cause

Hydraulic motors rely on adequate system pressure to operate. When there’s not enough pressure, the motor can’t start. The most common reasons for low pressure include:

1.1 Malfunctioning Valves or Blocked Lines

If directional, pressure, or flow control valves are damaged or clogged, the hydraulic fluid cannot circulate properly. This flow restriction prevents the motor from receiving enough oil pressure, leading to motor failure.

1.2 Relief Valve Set Too Low

The relief valve protects the hydraulic system by redirecting oil back to the tank once the pressure limit is reached. If this valve is set too low, pressure is released before it reaches the motor—causing the motor to stop functioning.

1.3 Incorrect Hydraulic Oil Viscosity

Hydraulic oil that is too thick increases system resistance, while oil that is too thin results in poor lubrication and sealing. Both extremes can reduce system efficiency and prevent the motor from producing the required torque.

1.4 Air in the Hydraulic System

Air contamination is especially common in newly installed systems. Air pockets disrupt pressure consistency, causing erratic or zero motor movement.

2. How to Troubleshoot a New Hydraulic Motor That’s Not Turning

Here are the recommended steps to diagnose and fix a hydraulic motor that isn’t rotating:

✓ Inspect the Hydraulic Lines and Control Valves

Ensure all lines are clean and valves are functioning correctly. Remove any blockages and replace damaged valves.

✓ Adjust the Relief Valve Pressure Setting

Reset the relief valve to an appropriate level based on the system’s working pressure. Ensure it is high enough for motor activation.

✓ Use the Correct Hydraulic Oil Viscosity

Select oil based on the ambient temperature and system requirements. Refer to the equipment manual for the recommended viscosity range.

✓ Bleed Air from the System

Run the motor without load for about 30 minutes to purge trapped air. Then shut down the system to cool and inspect for normal function.

3. Common Mistakes New Users Make

Especially for beginners, these often-overlooked issues can lead to premature troubleshooting or incorrect assumptions:

✘ Ignoring Component Compatibility

When connecting a new motor to an old system, mismatches may arise. For example, the motor’s flow demand may exceed the pump’s delivery capacity.

✘ Skipping System Calibration

Many users skip proper setup procedures like adjusting flow, setting system pressure, or air bleeding. This can lead directly to hydraulic motor startup failure.

By understanding these hydraulic motor troubleshooting steps, users can avoid unnecessary returns and ensure smooth motor operation. If the issue persists, consult with a professional or the equipment manufacturer for further diagnostics.