How to bleed brakes - Cars & Trucks

Bleeding brakes is pretty much the same across all vehicles. However, are you sure that there's air in the system and not a faulty brake master cylinder? The brake master cylinder has rubberised 'O' seals inside which, if worn, can cause a spongy pedal that has to be pumped before the brakes feel hard.



To bleed the brakes you need a length of plastic tube to fit onto the brake bleed nipple on the brake calliper. You can buy a brake bleeding kit which incorporates a non-return valve. The valve allows brake fluid to be pumped through it but prevents air from being drawn back up the tube into the brake system.



You can use ordinary plastic tube, but one end should be placed in a container of brake fluid to prevent air being drawn back in.



1. Locate the bleed nipple. Usually you start at the wheel nearest to the brake master cylinder (and then bleed each wheel in turn working your way to the furthest wheel from the car -if necessary).



2. Before you begin:Put a ring spanner onto the bleed nipple. Put a finger over the end of the bleed nipple to prevent air from entering via the nipple and 'rock' the spanner to make sure that the nipple will actually loosen. It is quite common for brake bleed nipples to seize then shear when turned with a spanner(wrench..). Don't use an open-ended spanner (wrench) otherwise the chances are you will 'round off' the bleed nipple.



3. Put the ring spanner on the bleed nipple and fit the bleed tube.

Get somebody to turn on the engine and slowly - slowly - depress the brake pedal. Undo the nipple slightly and brake fluid (maybe with air bubbles in it) should be visible in the tube.



get your helper to pump the brake pedal 3-4 times and keep the pedal depressed. Tighten the brake nipple.



4. Then repeat for each calliper if necessary.



5. Many cars have a split circuit brake system. That is, the front offside wheel is on the same system as the rear nearside wheel. The front nearside wheel is on the same line as the rear offside.



Here, you would bleed the front brake first and then the diagonally opposite rear wheel.










Plastic tube with non return valve for bleeding brake










Generic image - bleed nipple on calliper.








A bleed nipple. The open end is where the tube fits. Usually, you only need undo a bleed nipple approximately one turn. Use a ring spanner, not an open ended spanner.













Below: Bleed nipple can be seen on bottom right of calliper (generic image)






Below: Ring spanner on bleed nipple with tube attached.

If you dont have a bleeding machine its going to be a two man job.you need someone inside the veh and you are going to bleed the brakes make sure your brake fluid level is full at all times while doing this.start at the wheel at far end of your brake fluid bottle (ex if bottle is on right front of veh start at left rear wheel and work your way to R/R then L/F then R/F)your friend inside the veh is going to pump your brake pedal for about 10times to build up pressure on last pump he must press and hold brake pedal hard and you will open bleed nipple on brake Caliper and close it you are going to have to repeat this until you dont see any air bubbles in brake fluid thats coming out of the bleeding nipple be sure not to pump brake when nipple is still open this will cause a vacuum and let more are into brake fluid.while opening your bleeding nipple the brake pedal that your friend is holding will lower but this is normal if you close nipple and pump brakes is will get hard again. Hope this helps