- Posts: 149
- Joined: Aug 28th, 2010 12:48 am
- Tell us about your Corvette: 1974 base model. Mostly original but far from perfect. Been working on it for better part of 7 years. Body has been removed from chassis, chassis repaired and restored. Working on the mechanicals of the chassis as time/money allows.
- Location: Surprise, Az.
Did you "bench bleed" the master cylinder before hooking up the brake lines to the directional valve? Back in the day when I was an ASE mechanic working on cars for a living, when doing any kind of work where the master ran dry of fluid, it was imperitive to bench bleed the master. Even though it may be full of fluid, there is usually air trapped in it. I have two pieces of brake line with fittings that screw into the outlets of the master. They are bent so that they go back up into the master resevoir below the fluid level. Make sure the resevior is filled higher that the open end of the tubes. You can do this while the master is still on the car, just disconnect the brake lines and put in the bent tubes in their place.
Once the master is full of fluid, slowly pump the brake pedal, watching the ends of the tubing for air bubbles. You should see lots of bubbles at first then they get less frequent. Make sure the fluid never goes below the ends of the bent tubes! Very important, if the fluid gets too low, you'll need to start all over.
Once the bubbles are gone, tap the side of the master with a small hammer lighlty to dislodge any air still trapped in the master, and pump the brake pedal until the bubbles stop. Once ALL bubbles stop, put the cap back on the master, disconnect the bent tubes, and reconnect your brake lines. Then bleed the rest of the system as usual.
It' s a lot of work and a pita, but it's the only way to get all of the air out of the master cylinder.