Mechanics

Bleed and Flush Brake System

Easy step by step guide on how to bleed and flush an automotive brake system, though appearances may vary, the procedure is the same on most vehicles.

Difficulty Scale: 4 of 10

Tools and Supplies Needed

  • Small wrench set
  • Vacuum hose
  • Brake fluid
  • Protective clothing and gloves
  • Shop towels
  • Helper
Start with the vehicle on level ground, engine "OFF", lifted safely using jack stands, using everyday tools while wearing protective eyewear and gloves.

Step 1 - Locate and identify brake master cylinder fluid reservoir, fluid cap, lines, and fluid level sensor, check the system for leaks which is a sign of component failure (Note: Brake systems should never leak). Visit - Master cylinder replacement


Master Cylinder Fluid Reservoir

Step 2 - Using a shop towel, wipe the master cylinder fluid reservoir clean to prevent dirt from contaminating the fluid.


Cleaning Master Cylinder Reservoir

Step 3 - Grasp the lid and twist counterclockwise to remove, wipe off and set to the side.


Remove Master Cylinder Reservoir Cap

Step 4 - Insert a brake fluid removal tool (turkey baster) to remove as much old brake fluid as possible.


Remove Old Brake Fluid

Step 5 - Refill the master cylinder with new fluid until full (most vehicles use DOT3 or DOT4), consult the cap on the master cylinder or owners manual.


Refill Brake System

Step 6 - Reinstall the brake fluid reservoir lid.


Reinstall Reservoir Lid

Step 7 - Locate all four brake fluid bleeder fittings located near the top of each caliper or wheel cylinder.


Brake Fluid Bleeder

Step 8 - Using a small screwdriver or pick remove the bleeder dust cap.


Remove Brake Bleeder Cap

Step 9 - Use a boxed end wrench and rubber hose positioned onto and over the bleeder. (Note: Rubber hose is optional if brake fluid is cleaned off components once completed.)


Wrench and Hose Over Brake Bleeder

Step 10 - Have a helper push down on the brake pedal slowly and hold even pressure.


Push Down Slowly

Step 11 - Open one bleeder valve while the opposite end of the rubber tube is in a fluid container.


Open Brake Bleeder

Step 12 - Fluid will start to flow out of the bleeder or tube.


Brake Fluid

Step 13 - As the fluid flow slows, and while the pedal comes to the end of its travel, tighten the bleeder valve while maintaining pressure on the brake pedal. (Note: Do not allow the brake pedal up while the valve is open.)


Close Bleeder Valve

Step 14 - Once the bleeder valve is closed, allow the brake pedal to return to its normal position (Note: Never pump brake pedal). While watching brake fluid level in the reservoir, continue this process at each wheel until clean fluid is present with no air bubbles being expelled from the bleeder valve or hose.


Let Brake Pedal Up Slowly

Step 15 - Refill reservoir with brake fluid.


Refill Brake Fluid

Step 16 - Reinstall brake fluid reservoir lid.


Reinstall Reservoir Lid

Step 17 - Using a shop towel, wipe any spilled fluid, rinse with water if needed. After a flush or bleed is complete, check brake pedal operation, do not move vehicle unless normal braking operation is present.


Cleaning Master Cylinder Reservoir

Helpful Information

The brake bleeder screw can be fairly tight because bleeder screws seal against a taper fit seat in the wheel cylinder, or caliper. When loosening a bleeder apply WD40 or equivalent to aid rust removal, use a 6 point wrench or socket is best.

A brake system fluid change removes moisture and contaminants which causes brake system failures. Brake fluid is subject to extreme pressure and heat, the boiling point of the fluid is important for different applications, higher boiling points (severe duty) and anti-lock braking ABS systems require higher quality fluid, ratings are DOT2, DOT3, DOT4 and DOT5. Distinctive ratings define the chemicals the fluids are produced with such as mineral oil, ester glycol and synthetic oils.

Many of these fluids are not compatible, make sure to add and flush your brake system with the manufacturers recommended brake fluid.

Brake fluid is corrosive, but can be cleaned up with water.

Best Practices

  • Avoid accidental brake fluid spillage.
  • Add brake fluid from a sealed container to avoid moisture.

AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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