See Figures 1 and 2
Whenever a spongy brake pedal indicates that there is air in the system, or when any part of the hydraulic system has been removed for service, the system must be bled. In addition, if the level in the master cylinder reservoir is allowed to drop below the minimum mark for too long a period of time, air may enter the system, necessitating bleeding.
If only one caliper is removed for servicing, it is usually necessary to bleed only that unit. If, however, the master cylinder, warning valve, or any of the main system lines are removed, the entire system must be bled.
Be careful not to spill any brake fluid onto the brake surfaces or the paint. When bleeding the entire system, the rear of the car should be raised higher than the front. Only use brake fluid bearing the designation DOT 3.
The following procedure is acceptable for use on vehicles with and without ABS.
- Check to make sure that floor mats are not obstructing pedal travel. Full pedal travel should be 6 inches (15cm).
- Clean the cap and top of the master cylinder reservoir, and make sure that the vent hole in the cap is open. Fill the reservoir to the maximum mark.
Never allow the level to drop below the minimum mark during bleeding.
- If only one brake caliper or line was removed, it will usually suffice to bleed only that wheel. Otherwise, prepare to bleed the entire system beginning at the passenger side rear wheel.
- Raise the vehicle and support it safely.
- Remove the protective cap for the bleeder and fit a suitable line wrench on the nipple.
The calipers, on some models, are equipped with 2 bleeder screws. Attach one hose to each screw and submerge in brake fluid.
- Install a tight plastic hose onto the nipple and insert the other end of the hose into a glass bottle containing clean brake fluid. The hose must hang down below the surface of the fluid, or air will be sucked into the system when the brake pedal is released.
Open the bleeder nipple and pump the brake pedal 5 times. Keep the brake pedal depressed and close the nipple. Release the brake pedal and check the brake fluid. This should be repeated until the fluid flowing into the bottle is completely free of air bubbles. Continue to bleed the system in the following manner.
Drivers side rear wheel
During this procedure, check the master cylinder reservoir frequently.
- When completed, press the pedal to the bottom of its stroke and tighten the bleeder screw.
- Install the protective cap. If the pedal still feels spongy after bleeding the entire system, repeat the bleeding sequence.
- Fill the reservoir to the maximum line.
- Turn the ignition ON but do not start the engine. Apply moderate force to the brake pedal. The pedal must travel no more than 2.4 inches (61mm) without ABS; 2.17 inches (55mm) with ABS. The brake warning light (and ABS warning light) must not be on.
After bleeding the brake system, pressure test the brake system, by depressing the brake pedal with a force corresponding to an abrupt halt, almost sufficient to lock the wheels, for 30 seconds. Then check whether there has been any leakage of brake fluid from the master cylinder.
- Lower the vehicle.