Bonneville V6-3800 3.8L (1991)
Brake Bleeding: Service and Repair
With ABS System
Manual Bleeding
BLEEDING BRAKE HYDRAULIC SYSTEM
CAUTION: Do not move the vehicle until a firm brake pedal is obtained. Air in the brake system can cause loss of brakes with possible injury.
A bleeding operation is necessary to remove air from the hydraulic brake system whenever air is introduced into the system.
It may be necessary to bleed the hydraulic system at all four brakes when air has been introduced through a low fluid level condition, or the brake pipes
were disconnected at the master cylinder. When a brake pipe is disconnected at one wheel, only that wheel cylinder/caliper needs to be bled. When pipes
are disconnected at any fitting located between the master cylinder and brakes, then the brake system served by the disconnected pipe must be bled.
MANUAL BLEEDING
Fig. 1 Wheel Cylinder Bleeding
TOOLS REQUIRED:
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J 21472 Brake Bleeder Wrench
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J 28434 Wheel Cylinder Bleeder Wrench
NOTE: Remove the booster reserve by applying the brakes several times with the engine off until all reserve is depleted.
1. Fill master cylinder reservoir to proper level.
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Maintain fluid level in reservoir during bleeding operation.
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Have an assistant in the vehicle to press the brake pedal during bleeding operation.
IMPORTANT: Master cylinder reservoir cap must be installed before pressing on brake pedal during bleeding operation. This prevents brake
fluid spray from the reservoir.
2. When master cylinder is known or suspected to have air in the bore, then it must be bled before any wheel cylinder or caliper in the following
manner:
a. Loosen forward (secondary) brake pipe connection at the master cylinder.
b. Allow the brake fluid to flow from connector port. Maintain reservoir fluid level.
c. Tighten forward brake pipe on master cylinder.
d. Depress brake pedal slowly one time and hold. Loosen forward brake pipe connection at the master cylinder to purge air from the bore.
Tighten the connection and then release the brake slowly. Wait 15 seconds. Repeat the sequence, including the 15 second wait, until all air is
removed from the bore.
TIGHTEN
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Brake pipe to 15 Nm (133 lb. in.).
e. Repeat Step 2 and bleed the master cylinder at the rear (primary) brake connection.
3. Individual wheel calipers/cylinders are bled only after all air is removed from the master cylinder. If it is known that the calipers/cylinders do not
contain any air, then it is not necessary to bleed them.
4. When bleeding all the wheel circuits, use the following sequence:
a. Right rear.
b. Left rear.
c. Right front.