Service Notes

When to Bleed Brakes
A bleeding operation is necessary to remove air when it is introduced into the hydraulic brake system. It may be necessary to bleed the hydraulic system at all four brakes if air has been introduced through a low fluid level or by disconnecting brake pipes at the master cylinder. If a brake pipe is disconnected at one wheel, only that wheel caliper or cylinder needs to be bled. If pipes are disconnected at any fitting located between master cylinder and brakes, then the brake system served by the disconnected pipe must be bled.

Bleeding Master Cylinder
The time required to bleed the hydraulic system can be reduced if the master cylinder is filled with fluid and as much air as possible is expelled before the cylinder is installed on the vehicle. If the master cylinder is known or suspected to have air in the bore, then it must be bled before any caliper or wheel cylinder.

Manual or Pressure Bleed
The disc brake hydraulic system can be bled manually or with pressure bleeding equipment. Pressure bleeding is recommended for all hydraulic disc brake systems. Pressure bleeding equipment must be the diaphragm type and must have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture, oil and other contaminants from entering the hydraulic system. It is very important that the correct master cylinder bleeder adapters be used to avoid possible damage to the master cylinder reservoirs. On vehicles with disc brakes the brake pedal will require more pumping and frequent checking of fluid level in master cylinder during manual bleeding operation.

NOTE:
^ Never use brake fluid that has been drained from hydraulic system when bleeding the brakes.
^ Be sure the disc brake pistons are returned to their normal positions and that the shoe and lining assemblies are properly seated.
^ Care must be taken to prevent brake fluid from contacting any painted surface.
^ Power brakes require removing the vacuum reserve by applying the brakes several times with the engine off.
^ Before driving the vehicle, check brake operation to be sure that a firm pedal has been obtained.