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:
^ J 21472 Brake Bleeder Wrench
^ 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.
^ Maintain fluid level in reservoir during bleeding operation.
^ 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
^ 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.
d. Left front.

5. Raise vehicle and suitable support.
6. Remove bleeder valve cap and place proper size box-end wrench, J 28434, or J 21472, over caliper/cylinder bleeder valve.
7. Attach a transparent tube to bleeder valve, submerge other end of tube in a clear container partially filled with clean brake fluid.
8. Depress brake pedal slowly one time and hold.
a. Loosen bleeder valve to purge air from the caliper/cylinder.
b. Tighten bleeder valve, and slowly release brake pedal.
c. Wait 15 seconds, then repeat the sequence, including the 15 second wait, until all air is removed. This sequence may have to be repeated 10 or more times to remove all the air.

NOTE: Rapid pedal pumping pushes the master cylinder secondary piston down the bore in a way that makes it difficult to bleed the system.

TIGHTEN
^ Wheel cylinder bleeder valves to 7 Nm (62 lb. in.).
^ Caliper bleeder valve to 13 Nm (115 lb. in).

9. Install bleeder valve caps.
10. Lower vehicle.
11. Fill master cylinder to proper level.
12. Check brake pedal for "sponginess."
^ Repeat entire bleeding procedure to correct "sponginess."