How To Bleed The Automobile Brake System
A brake is a device used to slow or stop a vehicle, by friction; often installed on the wheels. Associate phrases are brake pad, brake pedal, brake fluid, brake oil, brake pipe, etc.
If the level of fluid in the reservoir is allowed to fall too low, or if any section of the brake pipe system is disconnected, the brakes will feel "spongy", due to air having been absorbed into the system. This air lock must be removed by bleeding the hydraulic system at the wheel cylinders; bleeding must always be carried out at all wheels, irrespective of which portion of the pipeline is affected. In addition it will be necessary to bleed the servo unit twice on Forward Control models.
The procedure at each point is exactly the same, and is as follows:
1) Attach a length of rubber tubing to the bleed nipple being dealt with, and place the lower end of the tube in a glass jar.
2) Slacken the bleed screw and pump the brake pedal sharply two or three times and then more slowly, pausing at each end of each stroke, until the fluid issuing from the tube shows no sign of air bubbles when the outlet is held below the surface of the fluid in the jar.
3) Hold the tube under the fluid surface and, while holding brake pedal in the depressed position, tighten the bleed screw.
The fluid in the reservoir should be replenished throughout the operation, to prevent another air-lock being formed
For the Forward Control models: Commence by bleeding at the servo unit, situated beneath the front of the vehicle, at the right hand side.
For All models: Slacken the shoe adjustment cams right off. Bleed the wheel cylinder which is farthest from the brake pedal.
Repeat for the other three wheels in turn, finishing at the one nearest the brake pedal.
For the Forward Control models: Re-bleed the servo unit.
For All models: Re-adjust the brakes.
Note particularly that the fluid reservoir for the brake is the outer portion of the combined reservoir.
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