This started this spring, last year I got the correct Delco moraine booster and master cylinder, all the brakes were also replaced. At that time I had brakes even thou I could not lock them during a panic stop. Now the brake pedal goes to the floor and the brake light comes on, replaced the master cylinder again and bled the brakes, starting at the right rear and moving to the front. Took the GS to the Syracuse Nationals and had to bleed the brakes again around the end of the second day there. The other thing that has me puzzled is, there is no missing brake fluid, every time I check cylinder is full.
If youre not losing fluid and the pedal goes to the floor and the light comes on, then theres air in the system. Did you use a pressure bleeding system? The best bet is to pressurize the system from the master cylinder reservoir and force the fluid through that way. I had a stubborn bubble stuck in my proportional valve/metering valve on my 72 skylark when I did my brakes. I had used a mityvac hand pump to bleed the brakes from the wheel ends. It just wasnt good enough. fluid would slip past the bubble. I then got a Mityvac pressure bleeder can for about $60 and used it to pressurize the lines from the Master Cylinder side, it worked like a charm. Good luck. sweet looking car by the way. I wish I had made it to the nationals - just didnt work out this year for me. I hear its a biiig show.
Did you bench bleed the master? You can bleed the brakes for days and still have air pockets if the master cyl. was not bench bled. Mark
Louie, I don't know if your car has original disc brakes or not. If it does & still has the original hold-off valve that attaches to the master cylinder & is held on by one of the nuts for the brake booster, this is what some refer to as the proportioning valve, it can, does & will suck air & NOT leak any fluid. If you can feel around where the little rubber nipple is & there is ANY moisture at all the valve is bad. I've been there & done that. It drove me crazy some years ago doing the same thing as you. Even my '68 Wildcat with the original disc brakes did that until I found out about this valve. You can replace masters till your blue in the face. They will seem to be OK for a day or two. Natural thinking is the master is bad. Just another FYI.
Tommy, I checked it today, and yes you are correct, it is moist, I will change it soon and see if the problem goes away. Thanks again :beers2:
This pass weekend I looked all over the county looking for the proportioning valve with negative results, had to order one from California
The check valve came in and I installed it this morning and bled the brakes, and away I went. Car is running faultlessly.
