Proper Way to Flush a Brake System
Your car's brake system needs to be flushed every one to two years. Over time, the brake fluid absorbs moisture, which lowers its boilin...
Your car's brake system needs to be flushed every one to two years. Over time, the brake fluid absorbs moisture, which lowers its boiling point and can cause corrosion from the inside. You need to completely replace the brake fluid in the system and make sure all of the old fluid is removed.
Replacing the Fluid
The old brake fluid is siphoned out through the master cylinder reservoir. The surface of the cylinder must be clean before you open it to prevent any dirt or contamination from entering the system. Use an aerosol cleaner on the reservoir with a clean rag or paper towels and make sure you clean every inch of the surface. Once the cylinder is clean, you can remove the cap on the cylinder to siphon out the fluid. A simple turkey baster can be used for this, but make sure it has never been used before and won't be used for anything else. Deposit the fluid into an approved container and make sure it doesn't drip anywhere onto the car; brake fluid will damage car paint. You should need a pint to a quart of fresh brake fluid to refill the cylinder, depending on the size of your car. You should be able to use either DOT 3 or DOT 4 fluid, but never use DOT 5--it's silicone based and can cause faster wear of the seals, allowing more water to enter.
Bleeding the System
Once you've filled the master cylinder with fresh fluid, you need to bleed any more old fluid from the system. This requires you to open all four of the car's bleeder screws; you'll need to raise the car on jack stands at all four ends and remove all four wheels to reach them. the bleeder screws are located on the brake calipers or the wheel cylinders. Have an assistant press down on the brake pedal for about 10 seconds as you loosen one bleeder screw to bleed the old fluid out, then close the screw and slowly retract the brake pedal back to its normal position to draw fresh fluid back into the system. You don't want the pedal fully depressed; placing a wood block behind it will help. Repeat this procedure with the next bleeder screw; it is usually best to start at the left rear wheel, cross to the right front, go down to the right rear and finish at the left front. Repeat on all the bleeders until you get fresh, clean fluid coming out of them. Use caution lowering the car from the stands after you replace the wheels, then refill the master cylinder with as much fluid as necessary.
