The term "bleeding the brakes" refers to a procedure where a controlled amount of brake fluid is removed from the brake hydraulic system at the lowest points; the brake cylinders at each wheel. This procedure not only removes any trapped air from the system, but it also purges the system of any abrasive solid particles or water-contaminated brake fluid that might be accumulating in the system. Bleeding the brakes on a regular basis will prolong the life of brake system components and will help to keep the system operating optimally. This procedure is well within the capabilities of most weekend DIY mechanics.
Instructions
- 1
Park the vehicle on firm and level ground. Put automatic transmissions in park, and manual transmissions in first or reverse gear. Set the emergency brake. Loosen the lug nuts on the rear passenger side wheel about one full turn each. Jack up the vehicle and support it securely on a safety stand. Finish removing the wheel.
2Find the bleeder bolt. This is a small bolt with an attached nipple which is usually found on the rear of a drum brake near the connection point between the brake line and the cylinder, or the rear or top of a disc brake caliper.
3Soak the bleeder bolt with penetrating oil and allow half an hour or more for the oil to work into the corrosion on the bolt threads. Use a good quality box-end wrench to slightly loosen the bolt. The bolt is fragile so do not force it. If the bolt will not move then soak it again with penetrating oil and let it stand for at least half an hour before attempting again. Do not apply heat to loosen the bolt as this may damage the rubber brake line and piston seals.
4Keep the wrench on the bleeder bolt while sliding a length of clear tubing over the bolt nipple. Place the opposite end of the tube in a container that is partially filled with brake fluid. The end of the tube should be submersed in the brake fluid in order to prevent air from flowing backwards into the system.
5Find the brake fluid reservoir. This is normally a translucent plastic container located near the rear of the engine compartment on the driver's side. Remove the reservoir cap and siphon the brake fluid out. Dispose of the used fluid as per local regulations. Refill the reservoir with new brake fluid that conforms with the vehicle manufacturer's specifications. Replace the reservoir cap.
6Loosen the bleeder bolt slowly until brake fluid begins to dribble out through the tube. Start the vehicle and push gently on the brake pedal a few times to push old brake fluid and any trapped air or contamination out through the bleeder bolt. Tighten the bleeder bolt, being careful not to overtighten or damage the bolt. Refill the brake fluid reservoir with new fluid and repeat the bleeding procedure until new fluid comes out of the bleeder bolt.
7Securely tighten the bleeder bolt, being careful not to damage or overtighten the bolt. Replace the wheel and lower the car.
8Repeat the procedure on the rear driver's side brake, followed by the front passenger side brake, and finally the front driver's side brake. The idea is to start with the brake furthest from the brake fluid reservoir and progress to the brake that is closest to the reservoir.
9Adjust the brake fluid level to the full mark on the reservoir, and test the brake operation before driving the vehicle.
