Master Cylinder: Installation
- Master cylinder must be bled before bleeding entire system. Master cylinder bleeding may be done on vehicle. Preferred method is to bleed master cylinder on bench. If master cylinder has a bleed screw, bench method should still be used. When master cylinder is installed on car, use bleed screw as a final check for trapped air.
- Place master cylinder level in a vise. Attach bleeding tubes to cylinder. Fill reservoirs with fluid so that ends of tubes are covered (see Fig 1). Tubes attached to disc brake outlets must have residual pressure valves installed over ends. This will keep tubes from siphoning.
- Stroke piston in bore with a wooden stick or dowel until bubbles no longer appear at ends of tubes. Remove tubes and plug the master cylinder disc brake outlets to keep fluid from draining.
- Install master cylinder on car, reversing removal procedure. Bleed master cylinder bleed screw first, if used, and then bleed remainder of system. See "Hydraulic Brake Bleeding" in this section.
- Check master cylinder compensating ports by pumping brake pedal several times, ending with pedal held down. Remove master cylinder cover and slowly release pedal. Fluid should squirt up in each reservoir from the compensating ports.
- If fluid does not squirt in each reservoir, port is plugged or pushrod is too long. Check for plugged port. If port is not plugged, adjust manual brake pushrod at clevis under dash. On power brakes, see Push Rod Adjustment under POWER BRAKE UNITS in this section. CAUTION: DO NOT use wire to check ports. Wire may make a burr on port or damage cup.
- Pushrod should have slight amount of play when in relaxed position, so that both master cylinder pistons will return to stops when brakes are off.