Have you noticed any difference in your braking power lately? If you’ve had your vehicle for a while, you may have noticed that your brakes just aren’t as responsive, or efficient as they used to be. Does it feel that you have to use more pressure on the brake pedal, and the brakes may seem to take a little longer to catch? If so, the reason for this is because the more you use your brakes, over time, bubbles of air may get into your brake lines, and this means that the brake fluid needed to cause your brakes to work is not getting to the brakes as effectively as before.
This can become a safety issue, leaving you less time to react to having to come to a fast stop, or worse, make your brakes useless while moving. The best way to fix this problem is to bleed you brakes to get the air bubbles out of the system. The National Motorists Association has a great walk through for brake bleeding.
Bleeding can be done several ways. The traditional two-man method requires one person to depress the brake pedal to the floor while the other opens the bleeder valve (there’s one at each wheel) to let fluid (and air bubbles) escape. Before the pedal is allowed to rise to its normal position, the second person must close the bleeder valve to prevent air from being sucked back in.
This process is repeated several times until all the air is gone.
During the process, the master cylinder must be kept topped off with fluid; otherwise, it can run dry and then you’ll just suck air into the system that way. Maintain the level at the “full” mark as you proceed.
Also: Be sure to close the lid on the master cylinder before you start pumping the brake pedal or you risk splashing everywhere. Be very careful with brake fluid because it will eat right through any paint it’s spilled on. It’s a good idea to cover the fender near the master cylinder with a rubber mat; something that won’t let any spilled fluid seep through to contact the paint. If you do accidentally spill any brake fluid on painted surfaces, stop what you’re doing and clean it up immediately. A spray-can detailer can save your car’s finish. Keep it handy.
Some mechanics like to attach a hose to the bleeder valve they’re working on, with the other end immersed in a container filled with brake fluid. This way, they can actually see the air bubbles — and when they stop coming.
This method also makes less of a mess, since you capture all the old fluid in your container instead of it squirting all over the floor.
Just be careful not to suck old fluid (and air bubbles) back into the system.
Do one wheel at a time; never open more than one bleeder valve at once.
Once you’ve purged all the trapped air from one wheel, move on to the next and repeat. The brake pedal should get firmer as air is removed from the system. Bleed the wheels in pairs — first the fronts then the rears. (Each set is paired and has its own separate fluid reservoir within the master cylinder.)
Having “soft brakes” can be a sign of potentially larger issues as well, so it’s best to have them looked at if you suspect you are having a braking issue. You are certainly welcome to follow the instructions above and attempt to bleed them yourself, however, not everyone may be comfortable fixing the problem themselves, if that is the case, then be sure to bring your Buick, or GMC to Freeman Grapevine as soon as possible.