Intermittent Brake Failure on Volvo L70: Troubleshooting and Solutions

[MikePhua]

Introduction
Experiencing intermittent brake failure on a Volvo L70 wheel loader can be a significant safety concern, leading to potential delays in work and increased repair costs. Brake issues, especially when they occur sporadically, can be difficult to diagnose. This article reviews common causes of intermittent brake failure on the Volvo L70, offers troubleshooting tips, and suggests possible solutions.
Symptoms of Brake Failure
Before diving into the causes, it’s important to understand the symptoms. In this case, the intermittent brake failure typically presents as inconsistent braking performance, where the brakes may work fine one moment and fail the next. Operators might notice:

• Soft brake pedal feel.
  
• Sudden loss of braking power during operation.
  
• Unpredictable stopping ability, especially under load.
  

If you’re experiencing these issues, you’ll want to address them immediately to avoid further damage to the braking system and ensure the safety of the operator.
Possible Causes of Intermittent Brake Failure

1. Low Brake Fluid Level
   • One of the most common causes of intermittent brake failure is a low brake fluid level. As fluid depletes, air may enter the brake lines, leading to a soft pedal or reduced braking performance.
     
   • Solution: Check the brake fluid level and top up if necessary. If the fluid level is consistently low, inspect the brake lines and master cylinder for any leaks.
     
2. Contaminated Brake Fluid
   • Contaminated or old brake fluid can cause inconsistent braking. Moisture or debris in the fluid can impair the brake system's function.
     
   • Solution: Replace the brake fluid if it appears cloudy or discolored. Ensure that the fluid is clean and at the appropriate level. Regular maintenance should include fluid checks and changes as per the manufacturer’s recommendation.
     
3. Worn Brake Pads or Discs
   • Worn-out brake pads or discs may not engage properly, especially under load, leading to unpredictable braking performance.
     
   • Solution: Inspect the brake pads and discs for wear. If they are below the recommended thickness, replace them. Ensure that all parts are functioning correctly and are properly aligned.
     
4. Faulty Brake Master Cylinder
   • The master cylinder is responsible for generating hydraulic pressure to activate the brakes. A faulty master cylinder may fail to build up adequate pressure, leading to sporadic braking performance.
     
   • Solution: Test the master cylinder for leaks or internal failure. If it is malfunctioning, it will need to be replaced or rebuilt.
     
5. Air in the Brake Lines
   • Air trapped in the brake lines can cause inconsistent braking, as it compresses when the brake pedal is pressed, preventing full brake engagement.
     
   • Solution: Bleed the brake system to remove any air from the brake lines. Ensure that all connections are tight to prevent air from entering the lines in the future.
     
6. Hydraulic System Issues
   • On a wheel loader like the Volvo L70, the braking system is often hydraulically powered. Hydraulic system malfunctions, such as a pump failure or low pressure, can lead to irregular brake performance.
     
   • Solution: Inspect the hydraulic system for leaks or low fluid levels. Check the hydraulic pump and valves to ensure they are working properly.
     
7. Faulty Brake Proportional Valve
   • A malfunctioning brake proportional valve can cause an imbalance in braking power, leading to inconsistent braking performance.
     
   • Solution: Test the brake proportional valve. If it's defective, replace it to restore proper brake function.
     
8. Electrical Problems
   • On some Volvo models, electrical components control braking functions. Issues with the brake control system, sensors, or wiring can lead to intermittent brake failure.
     
   • Solution: Inspect the electrical system for faults. Check for loose connections, damaged wires, or faulty sensors. Diagnose using an onboard diagnostic tool to pinpoint the issue.
     

Troubleshooting Steps

1. Visual Inspection
   • Begin by conducting a visual inspection of the brake system. Look for visible leaks, worn components, and any signs of damage. Check the fluid levels and the condition of the brake pads and discs.
     
2. Check Brake Fluid
   • Verify the brake fluid level and condition. If low, add fluid and inspect for leaks. Contaminated fluid should be flushed and replaced.
     
3. Brake Bleeding
   • If air in the brake lines is suspected, bleed the brakes to remove trapped air. Use the correct procedure and make sure all air is purged.
     
4. System Pressure Test
   • Conduct a pressure test on the hydraulic system to ensure the master cylinder and proportional valve are functioning properly.
     
5. Use Diagnostic Tools
   • If the issue is electrical, use diagnostic equipment to scan for error codes or faults in the braking control system.
     

Conclusion
Intermittent brake failure on the Volvo L70 can be caused by a variety of issues, ranging from low fluid levels to faulty hydraulic components. By understanding the potential causes and following a methodical troubleshooting process, operators and technicians can quickly identify and resolve the problem, ensuring the loader’s braking system works as intended. Regular maintenance and inspections can prevent many brake-related issues from occurring and prolong the lifespan of the equipment.
Always ensure that safety is the top priority when working with heavy machinery. If the problem persists, consult a professional technician to further diagnose and repair the system.