How To Bleed Your Brakes

Why you need to bleed your brakes

Bleeding your brakes is essential for maintaining proper brake performance and safety. Air trapped in the brake lines reduces braking efficiency because air compresses, unlike brake fluid. This can lead to a spongy brake pedal feel, longer stopping distances, or even brake failure. By removing air through the bleeding process, you restore full hydraulic pressure to the system, ensuring responsive and reliable braking. Regularly bleeding your brakes, especially after repairs, helps keep your vehicle safe on the road. 

How to bleed your brakes

While one person can bleed a brake system successfully, it should be noted that since bleeding a brake system can sometimes be a complicated affair, we highly recommend that you enlist an assistant to make things easier. Note also that you will need some basic tools and equipment, including the following:

TIP: Apart from the tools and equipment listed below, you may want to consider investing in a vacuum or pressure based tool that eliminates the need for an assistant. These kinds of tools are available from most auto parts stores and come in a wide variety; from simple hand-held, manual vacuum pumps that suck brake fluid into a small container, to bulky equipment that requires a compressor to work. Note that while simple hand-held vacuum pumps are often adequate to bleed simple brake systems, bleeding complex brake systems on high-end vehicles usually requires the use of complex and expensive equipment that often includes a separate compressor if a compressor is not incorporated into the equipment- as is sometimes the case.

  • A sufficient quantity of clean brake fluid; we recommend about 500 ml of brake fluid that is recommended for the vehicle in a sealed container. Using brake fluid from sealed containers only will largely prevent the introduction of contaminants like water into the brake system
  • About a metre or so of silicone tubing; aquarium tubing works well
  • A 600 ml soft drink bottle cut down to about half its height
  • A suitable spanner, or selection of suitable spanners that will fit the bleeding nipples on the calipers and/or wheel cylinders
  • A few large highly absorbent cloth towels or rags to wipe off brake fluid spills, or a supply of sawdust to absorb brake fluid spills on the ground or garage floor
  • A set of four suitable and rated jack stands to place under the vehicle’s specified(!) support points
  • A suitable and rated jack that can lift the vehicle off the ground- one axle at a time

 WARNING: Since brake fluid is extremely corrosive, and its corrosive effect on painted surfaces is almost immediate, place a thick layer of newspaper or similar under the brake master cylinder reservoir to prevent brake fluid from coming into contact with the vehicle’s paint when refilling the reservoir during the bleeding process.

 

STEP 1
Start at the wheel that is furthest away from the master cylinder. Fit a suitable spanner onto the bleeding nipple, and slip one end of the silicone hose over the bleeding nipple’s end so that it fits securely. Place the other end of the hose into the cut-down soft drink bottle, and pour a small quantity of brake fluid into the container. Make sure the end of the silicone hose is fully submerged to prevent air from being sucked back into the brake system.
 
STEP 2

Have your assistant apply a firm pressure on the brake pedal, but make sure they maintain this pressure. Crack open the bleeding nipple, and observe what spurts out; in most cases, the brake fluid spurting out will be dirty, and there may not be any visible air bubbles in the old fluid. Close the bleeding nipple, and let your assistant remove pressure from the brake pedal.

STEP 3

Repeat this process until the brake fluid that spurts out of the bleeding nipple is clear and free of visible air bubbles. Note that this process requires a fair bit of coordination between yourself and your assistant; they should not allow the brake pedal to rise before you have closed the bleeding nipple, so be sure to communicate clearly. Note also that it is important not to let the brake fluid reservoir on the master cylinder run dry- if this happens, you will simply be pumping air into the brake system, so have your assistant check and replenish the brake fluid level in the reservoir constantly.

 

STEP 4

Once the brake fluid emerging from the first wheel is clear and free of air bubbles, repeat the process on the next furthest wheel from the master cylinder until the brake fluid on all four wheels is clear and free of air bubbles.

 

STEP 5

Check the operation of the brakes by starting the engine and stepping firmly on the brake pedal; if the system is free of air, the brake pedal will be rock-hard. There should be no “sponginess”, or abnormal pedal travel, and the pedal should not sink towards the floor under pressure.

Note, however, that damaged rubber brake hoses and master cylinder seals can cause the brake pedal to remain spongy or soft, so be sure to replace all suspect brake parts if bleeding the brakes does not resolve a spongy or soft brake pedal.

 The brake pedal should feel solid, not spongey. 

 

STEP 6

Top off the brake fluid level strictly to the “Maximum” mark on the reservoir, and clean up all brake fluid spills. Note that since brake fluid is water soluble, brake fluid spills on the hubs and calipers can easily be removed by spraying the hubs with a garden hose or pouring clean water over the hubs with a bucket or similar implement.

  

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