Flushing Old Fluid and/or Excessive Air Out of Your Brake System

Jan 30, 2020

At Grafco Electric, we understand the importance of maintaining your vehicle's brake system to ensure optimal performance and safety. Regularly flushing old brake fluid and removing excessive air from the system is crucial for maintaining the effectiveness of your brakes. In this comprehensive guide, we provide step-by-step instructions on how to flush old brake fluid and eliminate excessive air, enhancing brake performance and overall safety.

Why is it Important to Flush Old Brake Fluid and Remove Excessive Air?

Over time, brake fluid can become contaminated with moisture, dirt, and debris, compromising its effectiveness. Additionally, air can enter the brake system through leaks or improper bleeding, leading to diminished brake performance and potential safety hazards. Flushing old fluid and removing air from the system is essential for the following reasons:

  • Improved Braking Performance: Regularly flushing the old fluid and eliminating air ensures the brake system operates at its full potential, providing better stopping power.
  • Extended Brake Components Lifespan: By maintaining clean brake fluid and a properly bled system, you can help prevent premature wear and damage to brake components, resulting in cost savings over time.
  • Enhanced Safety: Efficient brakes are crucial for safe driving. Flushing old fluid and removing air reduces the risk of brake failure, helping to keep you and other road users safe.

Step-by-Step Guide to Flushing Old Brake Fluid and Removing Excessive Air

Follow our detailed instructions below to successfully flush your old brake fluid and remove excessive air from your brake system:

Step 1: Gather the Necessary Tools and Materials

To properly flush old brake fluid and remove air, you will need the following tools and materials:

  • Brake fluid (check your vehicle's manual for the recommended type)
  • Wrench or ratchet set
  • Clear plastic tubing
  • Bleeder wrench or line wrench
  • Container to catch old brake fluid
  • Fresh clean cloth or rag

Step 2: Locate the Brake Bleeder Screw

The brake bleeder screw is typically located at each brake caliper or wheel cylinder. Refer to your vehicle's manual to identify the exact location.

Step 3: Prepare the Brake Bleeding Process

For best results, consult your vehicle's manual for specific bleeding instructions. In general, follow these steps:

  1. Secure the Vehicle: Park your vehicle on a level surface and engage the parking brake.
  2. Remove Excess Brake Fluid: Wipe away any debris or dirt from the brake fluid reservoir cap before opening it. Remove excess fluid to prevent overflow during the bleeding process.
  3. Prevent Contamination: Brake fluid absorbs moisture quickly, so avoid leaving the reservoir open for an extended period. Immediately cover the reservoir with a clean cloth or plastic bag after removing the excess fluid.

Step 4: Bleed the Brakes

Now it's time to bleed the brakes following these steps:

  1. Start with the Furthest Wheel: Begin with the wheel farthest from the master cylinder, typically the rear wheel on passenger cars. If you're uncertain, consult your vehicle's manual.
  2. Attach the Tubing: Attach one end of the clear plastic tubing to the bleeder screw and the other end to a container to collect the old brake fluid.
  3. Open the Bleeder Screw: Loosen the bleeder screw with the bleeder wrench or line wrench. Ensure the tubing is securely attached to prevent air from entering the system.
  4. Have an Assistant: Enlist the help of an assistant to press and hold the brake pedal firmly while you turn the bleeder screw counterclockwise to expel the old fluid and air.
  5. Close the Bleeder Screw: Once the fluid flow stops and only clear fluid comes out, tighten the bleeder screw firmly. Instruct your assistant to release the brake pedal slowly.
  6. Repeat the Process: Repeat steps 2 to 5 for each brake caliper or wheel cylinder, working from the farthest wheel to the closest to the master cylinder.

Step 5: Check Brake Fluid Level and Top Up

After bleeding all the brakes, check the brake fluid level in the reservoir. If necessary, top up with fresh brake fluid recommended by your vehicle's manual.

Step 6: Test the Brake Pedal

Pump the brake pedal a few times to ensure it feels firm and doesn't sink to the floor. If the pedal feels spongy or abnormal, repeat the bleeding process.


Regularly flushing old brake fluid and removing excessive air from your brake system is crucial for maintaining optimum brake performance and safety. Following the steps outlined in our comprehensive guide will help you effectively flush old fluid and eliminate air, ensuring your brakes operate at their full potential. Remember to consult your vehicle's manual for specific instructions and recommended brake fluid type. If you're unsure or uncomfortable performing this procedure, it's always best to seek professional assistance from a trusted and qualified automotive technician. Drive safely!