Why is My Volvo Excavator’s Boom or Arm Moving Slowly?

A Volvo excavator’s boom and arm are critical for digging, lifting, and operating attachments. If the boom moves slowly, hesitates, or lacks power, it may be caused by low hydraulic pressure, clogged filters, failing control valves, or worn hydraulic cylinders. Below, we’ll explore the most common reasons why a Volvo excavator’s boom is slow to respond and how to fix it.

Common Causes of Slow Boom and Arm Movement in Volvo Excavators

1. Low Hydraulic Fluid or Contaminated Oil

Hydraulic fluid is the power source for all boom and arm functions. If it’s low or dirty, movement may be sluggish.

Solution:

  • Check the hydraulic fluid level and top off if needed using the recommended oil listed in your Volvo excavator service manual.

  • If the fluid is contaminated (milky or dark), flush and replace it.

  • Inspect for hydraulic leaks in hoses, fittings, and cylinders.

2. Clogged Hydraulic Filters or Screens

A blocked hydraulic filter can restrict fluid flow, reducing speed and response time for the boom and arm.

Solution:

  • Replace the hydraulic filter at recommended service intervals.

  • Inspect the return line filter and clean it if necessary.

  • Follow filter maintenance steps in your Volvo repair manual.

3. Weak or Failing Hydraulic Pump

A failing hydraulic pump can’t generate enough pressure for the boom to move efficiently.

Solution:

  • Use a pressure gauge to test hydraulic pump output and compare it to manufacturer specifications.

  • If the pressure is too low, rebuild or replace the pump.

  • Follow pump diagnostics in your Volvo excavator hydraulic system manual.

4. Faulty Boom Control Valve or Relief Valve Malfunction

If the boom control valve is stuck or the relief valve is set incorrectly, it can restrict hydraulic flow to the boom and arm.

Solution:

  • Test the relief valve and adjust if necessary.

  • Inspect the boom control valve for blockages or internal wear.

  • Use the Volvo excavator service guide for troubleshooting and valve adjustments.

5. Worn or Leaking Hydraulic Cylinders

If the boom drifts down after lifting or moves erratically, the hydraulic cylinder may be bypassing internally.

Solution:

  • Check for visible leaks around the cylinder seals.

  • Perform a bypass test to see if fluid is leaking past the piston seals inside the cylinder.

  • If necessary, rebuild or replace the hydraulic cylinder using the Volvo excavator repair manual.

6. Air in the Hydraulic System

Trapped air in the hydraulic lines can cause delayed or jerky movement in the boom and arm.

Solution:

  • Bleed the hydraulic system to remove air pockets.

  • Check for leaks that may be allowing air to enter the system.

  • Follow air-bleeding procedures in your Volvo equipment manual.

Preventive Maintenance for Volvo Excavator Boom and Arm

To prevent sluggish movement in the future:

  • Regularly check and change hydraulic fluid and filters.

  • Monitor pump pressure and control valve performance.

  • Inspect and replace worn hydraulic cylinders and seals.

  • Follow scheduled maintenance in your Volvo excavator manual.

Get the Right Manual for Your Volvo Excavator

A Volvo excavator service manual is essential for diagnosing and fixing slow boom movement, hydraulic failures, and valve issues. At PDFManualsShop.com, we provide Volvo hydraulic system repair manuals with step-by-step troubleshooting guides, system diagrams, and maintenance procedures.

We also offer manuals for Case, John Deere, Kubota, and Bobcat.

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