[Eddies66]

A second alternative is the vacuum bleeding kit. This kit works in the opposite manner of the pressure bleeder, applying a vacuum to the brake system in order to draw brake fluid out of the car. The system works well, but can sometimes cause air bubbles to form in the lines. Particularly on cars with rear brake proportioning valves like the Porsche 914, the vacuum system can leave air trapped in these valves, giving a spongy pedal as a result. When using the vacuum bleeding system, the best approach is to bleed each corner of the car several times, in order assure that all the air is out of the system. Simply fill up your brake reservoir, attach the pump system, pump up some vacuum, and then open the bleed nipple. Brake fluid should be pulled out of the system when the vacuum is applied. If it’s not – you may have a problem with your brake lines.