[kyle_blake]

hi,

my stock 69 gto that came with front disc and rear drum from factory kept having my brake pedal go soft after repeated gravity bleed. would work for 2-3 drives then soft. After many mechanics, and no real direction, I finally looked behind rubber button on hold off valve and brake fluid was there, so i bought a replacement valve.

After a very long time of replacing everything else everywhere and bypassing the valve
i believe i experienced symptoms of residual pressure always pushing down the front brake pads as i drove around and heating up the rotors 135 F . maybe it would go up more if i kept driving. i do not know norms.

Oh and once a shop a loosened the bleeder valve on caliper after driving for 50 mins and the fluid "shot out" of it like pressure had been built up? just sharing some what shop told me. that is not normal. all my old brake posts are are around on py. figured i'd start new.

I installed the valve yesterday and went to manually bleed the brakes using 2 man method and it doesn't seem to want to push fluid past out of the valve down to front brakes. i tried about 9 presses. i did not try it with car started doing that.


Just wondering if anyone has had same experience? Clearly I can not gravity bleed it. It is the PV68 model number. right stuff i believe makes it.

I have a friend with a pressure bleeder to try. i believe it can go over 15 psi down from master cylinder to all 4 tires.

Any comments would be appreciated, thanks so much... happy pre green drinking st patricks day coming up.

ps - there is a rubber button on backside of part that one can press which moves the valve inside but i forgot what that is for?

thanks

[Formulas]

Crack open the line connection right before your rubber lines to verify yes or no getting past your new valve... ... A couple things high on the list of brake hold on or not working is collapsed rubber flex lines and sticky caliper pucks

[scott70]

My 70 gto has the valve right under the master cylinder. I have to push that button during bleeding. I believe GM actually had a tool to do it but I remember right I wedged a chisel between the button and the power brake booster to hold it in.

[grivera]

As Scott mentioned, the button has to be pressed constantly during the front brakes bleeding process. I bled the brakes on my 69 Lemans using a pressure bleeder and you could easily see the difference in flow with button pressed vs not pressed.

[scott70]

Also as you probably know that rubber is just a protector… the actual button is small and metal underneath the rubber.

[kyle_blake]

Thanks very much. i'll try and push the button that pushes the cylinder valve up then re-try bleeding / gravity. thank you again everyone.