Do you want to bleed the brakes of your car to give them new life? Have you recently replaced your brake pads, but does it feel spongy when you press the brake? If the level of the brake fluid in the cylinder reservoir becomes too low, air bubbles sometimes enter the brake line, reducing the strength of the brake fluid reservoir. Letting the air out of the brake fluid reservoir will restore full power to the hydraulic brakes.
Step 1. Remove the cap from the cylinder reservoir
It is usually a light colored reservoir with a black cap and it is usually aligned with your brake pedal in the engine compartment.
Step 2. Pull out the old fluid
Use a pipette to remove as much of the old, inky liquid as possible.
Step 3. Clean the reservoir
After removing all the old brake fluid, clean the reservoir with a clean, lint-free cloth if possible. Do not spill brake fluid on painted surfaces as this will dissolve the paint almost immediately. Clean up any spills with a brake fluid cleaner or soap and water.
Step 4. Fill the cylinder with clean brake fluid
Replace the reservoir cap.
Step 5. Depress the brake pedal a number of times (15 times or more)
Step 6. Loosen the vent valves
Using a spanner (usually 5/16) that fits the bleed bolt, loosen the bleed valves, but leave them closed. To make it easier to loosen the bolts, you can spray or drip some oil on the bolt the day before.
Step 7. Connect a tube to the vent bolt
Take a piece of clear plastic tubing (e.g. aquarium tubing) and push one end over the vent bolt.
Place the other end of the tube in a small, clear bottle containing 2 to 5 cm of fresh brake fluid. (This prevents air from being sucked back into the brake cylinder or brake line.)
Step 8. Place a 2.5 x 10 cm piece of wood, or another spreader, under the brake pedal
This prevents the brake pedal from coming down too far when you start bleeding. It is necessary to avoid completely emptying the pistons in the cylinder, which could cause leaks in the cylinder.
Step 9. Refill the cylinder reservoir
Remove the cap from the reservoir again and fill the reservoir with fresh brake fluid. Keep the cylinder filled during the venting process to prevent air from entering the system.
Step 10. Replace the cylinder reservoir cap
Step 11. Have an assistant sit in the driver's seat and slowly depress the brake pedal, with equal force, and hold it down
The assistant should indicate when the pedal has been pressed as low as possible.
- Remark: Not much force is needed. Push the pedal down as far as you normally would to come to a complete stop.
Step 12. Start with the rear right wheel (on cars where the driver is on the left)
Turn the bleeder bolt a quarter turn counterclockwise. Old liquid and air will enter the bottle through the tube. When no more liquid comes out, close the vent valve again.
- Remark: warn your assistant that the brake pedal will move further down when you loosen the bleeder bolt a quarter turn. It is normal for this to happen. Your assistant should keep the pressure on the pedal and follow it down until it stops, then hold it in place.
Step 13. Alert your assistant when he or she needs to take their foot off the brake pedal, causing it to come back up
Step 14. Repeat this process until fresh, clear liquid comes out through the tube
After every 5th time the brake pedal is depressed, the cylinder reservoir must be topped up with brake fluid. Do not let the level get too low, otherwise air will be sucked into the cylinder.
Step 15. Retighten the bleed bolt
Step 16. Repeat steps 12 through 15 for the left rear wheel
Step 17. Repeat steps 12 through 15 for the right front wheel
Step 18. Repeat steps 12 through 15 for the left front wheel
Step 19. Done
Your brakes are now bled. Thank your assistant by treating him or her to a drink. Never take help for granted.
Step 20. Never use brake fluid that is not suitable for your car
- Some auto shops sell cheap brake bleeding kits, these are very useful.
- Some car models require a specific venting procedure known as a venting sequence due to the different valves and systems used. To avoid problems with and/or damage to the brake system due to improper bleeding, seek the advice of a professional before attempting to do it yourself.
- Place a small tube at the end of the vent valve. Place the other end in a bottle containing brake fluid. Loosen the valve, press the brake pedal and make sure to keep the reservoir full.
- If you don't know what you are doing, get help from a professional. Improper bleeding can allow air to enter the system and cause improper operation of the brakes.
- For ABS (antilock brake systems) brakes, the pump and valves may require special tools during the bleeding process. If your vehicle has ABS brakes or traction control, do not attempt to bleed your brakes without the specialized tools to activate the necessary systems during the bleed process.
- Always start with the wheel furthest from the master cylinder. The order is usually back right, then back left, then front right, then front left.
- Vent bolts can be difficult to remove. Use a well-fitting spanner to avoid damaging them.
- Doing this process alone is NOT RECOMMENDED, air may be drawn in through the vent valve screw! If you use a pressure vent, the process can be carried out by one person.
- Brake fluid is strong stuff. Keep it away from your eyes and spill as little as possible. If possible, use a tube and container to collect and recycle any liquid squirting from the car.
- Brake fluid will corrode your car's paint! Be careful not to spill!
- Always use the brake fluid recommended by the manufacturer for your car. Using incorrect fluid (such as engine oil) can lead to brake failure, which is a serious problem. If you survive the failure of the brakes, you will have to replace some very expensive parts on your car-perhaps even the entire car.