Buick LeSabre 1986-1999
Buick Park Avenue 1996-1999
Oldsmobile 88 1992-1999
Oldsmobile Delta 88 1986-1988
Oldsmobile LSS 1996-1999
Pontiac Bonneville 1987-1999
Old brake fluid is often the cause of spongy brakes returning a week or so after bleeding the system. If all parts check good. Change the fluid by repeated bleeding.
- Deplete the booster reserve by applying the brakes a few times with the engine OFF until all reserve is depleted.
- Fill the master cylinder reservoir to the full level mark with brake fluid from a fresh, sealed container. You must maintain the fluid level during the bleeding procedure.
If the master cylinder is known or suspected to have air in the bore, bleed it as follows before bleeding any of the wheel cylinders or calipers:
- Loosen the forward brake line connection and the master cylinder.
- Fill the master cylinder until fluid begins to flow from the front pipe connector port, maintaining the fluid level.
- Tighten the front brake pipe on the master cylinder securely.
- Have an assistant depress the brake pedal slowly one time, and hold. Loosen the forward brake pipe connection again to purge air from the bore. Tighten the connection and then slowly released the brake pedal. Wait 15 seconds. Repeat the sequence, including the 15 second wait, until all air is removed from the bore.
- Tighten the brake pipe connection to 11 ft. lbs. (15 Nm).
- After all the air has been removed from the front connection, repeat the same procedure at the rear connection of the master cylinder.
- Individual wheel cylinders and calipers are bled only after all the air has been removed from the master cylinder.
If all of the wheel circuits must be bled, use one of the following two sequences, depending upon the year of your vehicle:
- 1986-90 vehicles: right rear, left front, left rear, then right front.
- 1991-99 vehicles: right rear, left rear, right front, then left front.
- Fill the master cylinder reservoir with brake fluid. Keep the level at least 1 / 2 full during the bleeding operation.
- Raise and support the vehicle safely.
- Remove the bleeder valve cap, and place a proper size box end wrench, or suitable bleeder wrench, over the bleeder valve.
- Attach a transparent tube to the bleeder valve, and submerge the other end of the tube in a clear container, partially filled with clean brake fluid.
- Have an assistant slowly depress the brake pedal one time, and hold.
- Loosen the bleeder valve to purge the air from the cylinder.
- Tighten the bleeder screw, then slowly release the brake pedal. Wait 15 seconds.
- Repeat this sequence until all the air is removed. Depending upon the amount of air in the system, you may have to repeat the sequence at least 10 times to remove all of the air from the system.
- Lower the vehicle and refill the master cylinder.
- Check the brake pedal for sponginess. If the pedal is spongy, repeat the entire bleeding procedure.
- For 1994-99 vehicles, use a Tech 1® or equivalent scan tool to pressure bleed the brake system, using the "Auto Bleed" sequence. Then, repeat the wheel cylinder and caliper bleeding sequence.