How to Make Sure You Remove Any Air from Your Vehicle's Braking System
A family car has hundreds of components that must work together in harmony in order to move it from point to point. You could argue that each one of these components is critical, but none is more important than the braking system. If you've noticed something "strange" when you're trying to press the brake pedal and it seems to be moving further than it usually does, you need to take action as soon as possible to get brake repairs. What should you do before attempting to drive the vehicle any further?
Time to Bleed
This kind of scenario indicates that the vehicle's braking system has excessive air within it and this needs to be removed. The good news is that the manufacturers have built in some special tools that will allow you to "bleed" the air out and restore everything to normal. It requires a fair degree of effort and a little manual dexterity, but can typically be done within your garage at home.
Begin by raising up the car and putting axle stands underneath each corner, so that everything is safe. If you're happy, then you can remove the road wheels.
Have a look behind the brake disc at the corner of the caliper and locate the bleed screw. Using a ring spanner, carefully turn this so that you open the valve. Just be careful not to use excessive force, as you could damage it. Attach some clear plastic tubing over the end of the bleed "nipple" and put the other end into an empty container.
Next, open the bonnet and make sure that there is enough brake fluid in the master cylinder. If not, add some but then leave the lid off the top of the master cylinder before proceeding.
Get a friend to sit in the driver's seat and "pump" the brake pedal slowly but surely, while you hold the pipe carefully so that the fluid and the trapped air is pushed out of the system and into the container. After this has been done several times, your assistant should depress the pedal and hold it, while you tighten the bleed screw.
Once you have completed this process for the first wheel, check to make sure that there is enough fluid in the master cylinder under the bonnet and if not, add some more. Then, repeat this entire procedure for each of the other three wheels, until you can see that there are no more air bubbles in the evacuated solution and the brake pedal feels "firm" once again.
Your Next Move
Air in the system can build up from time to time, but this is generally also an indication that you need to take the vehicle in for a complete brake service check and this should be next on the agenda.