Tech Tips | Brake Bleeding
What is brake bleeding and why is it necessary?
Brake fluid is an essential part of the brake system. The pressure you place on the brake pedal moves the brake fluid which in turn moves the brake parts to slow the wheel. Over time, brake fluids can be contaminated with moisture and rust, which impedes your ability to properly brake and stop the vehicle. Most car manufacturers recommend replacing brake fluid every three years. Brake bleeding not only gets air out of the brake system, but can refresh the system with new brake fluids by following the steps below.
• Vacuum brake bleeder
• Air compressor (>2 CFM)
• Your vehicle’s specified brake fluid
• Bleeder wrench (box end wrench recommended)
• Shop rags or towels
• Car jack
• Jack stands
Vacuum Brake Bleeder
1. Get access to bleeder screws – Safely raise your vehicle with a floor jack and lower onto jack stands. (Never get under a vehicle that is only supported by a floorjack) Remove tires to gain access to bleeder screws located on the vehicle’s brake calipers.
2. Set up – Begin by hooking up your assembled vacuum brake bleeder to an air compressor capable of at least 2 CFM.
3. Extract old fluid from master cylinder
(1) Turn on air compressor.
(2) Remove master cylinder reservoir cap and insert brake bleeder nipple into the reservoir.
(3) Depress the air flow handle to evacuate old fluid from the reservoir.
(4) Remove bleeder nipple from the reservoir once old fluid has been extracted.
4. Top off brake fluid – Top off master cylinder reservoir to the maximum level with fresh brake fluid. Refer to the vehicle’s service manual for the correct brake fluid type.
5. Slide the correct sized box wrench on the bleeder screw. Push the rubber bleeder nipple over the bleeder screw. Consult the vehicle’s service manual for the correct brake bleeding sequence. Typically, you should start at the brake that is furthest from the master cylinder reservoir, usually the passenger side rear brake.
6. Prepare the vacuum bleeder
(1) Turn on air compressor.
(2) To apply suction, depress the air flow handle.
(3) Move the air flow handle securing clamp over the handle for continuous suction.
7. To begin bleeding your brakes, loosen the bleeder screw on the vehicle about a 1/2 turn until brake fluid draws out. Ensure the master cylinder reservoir does not run empty as this will introduce air to the brake system causing your brakes to operate improperly. Avoid this by ensuring the master cylinder has fresh brake fluid at all times and is topped off before beginning bleeding your brakes.
8. Bleed the brake system until fluid runs clear and no bubbles are visible in the bleeder hose. Close the bleeder screw to stop extraction and remove the rubber bleeder nipple from the bleeder screw.
9. Repeat steps 4 to 7 going from the passenger side rear to the driver side rear, passenger side front and finish with the driver side front brake, unless otherwise specified by the vehicle’s service manual.
10. Check the master cylinder reservoir fluid level once all brakes have been bled. Fill to maximum level and replace master cylinder cap.
11. Inspect your work. Run the engine and depress the brake pedal to ensure firm braking. If braking is spongy, air may be in the system and the bleeding process should be repeated.