no pressure on power brakes
Posted: Sun Jul 16, 2017 3:19 pm
Hi guys,
Last year, Matthew helped me out to install a new M/C on my 59SF with power brakes. Afterwards I got the brakes tested and everything worked just fine. Car had been sitting in the garage since and while we switched the idler arm a couple weeks ago, I realized a brake fluid leak on the front right wheel. Usually the pedal then starts to vibrate when being pressed down as there's not enough fluid in the M/C, which it did. Anyways, pressure was still there. Matthew supposed, one of the wheel cylinders is the cause of the leak, so he was so kind to get me four new cylinders for the front drums.
I changed all four cylinders, one wheel at a time with the brake pedal jacked to the floor. I had to disassemble the plate to get the cylinders out so I figured it'd be a good opportunity to clean out everything. Reassembled everything and was ready to bleed the brakes today. Started out with a pneumatic brake bleeder first, but it seemed to suck air on the bleeder screw, so I went on to the manual procedure and asked my gf to pump the pedal. Effed up again on the first try as I didn't tell her to hold the pedal pressed to the floor after pumping before I close the screw (dumb, I know). So I guess after bleeding all four wheels like that, there still got air sucked into the system. Started the whole procedure again with the RR wheel, then RL, then FR, then FL, until all valves came out clean (to my best knowledge). Filled up the M/C after each valve. Checked every valve for leaks and the system is dry. So I went on and started the engine to test pressure on the pedal - nothing (and of course no brake effect at all). Here's what I tried so far:
- recurring pumping of the pedal with engine off: no pressure/resistance
- recurring pumping of the pedal with engine running: no pressure/resistance
- I can see the booster moving when I press the pedal with the engine running. Since it worked two weeks ago, I'd suppose it's no vacuum problem. Engine idles slightly up when I press the pedal.
- However I detached the rubber hose from booster to reservoir and there was a "swish" sound, so that seems to build up just fine (put it back on afterwards)
I wondered if I should:
1. adjust the brake shoes via the screws at the back of the drum as explained in the manual
2. bleed again
3. could there be air in the M/C and if so, is there a way to bleed the M/C while on the car
Or anything else?
Since I couldn't find any leaks and it used to build pressure even with the leaking wheel cylinder, I'd guess, air in the system causes the pressure to fail. The two failed attempts to bleed the brakes properly might also have sucked air into M/C?!?
Would be grateful for any input! Thank you
Last year, Matthew helped me out to install a new M/C on my 59SF with power brakes. Afterwards I got the brakes tested and everything worked just fine. Car had been sitting in the garage since and while we switched the idler arm a couple weeks ago, I realized a brake fluid leak on the front right wheel. Usually the pedal then starts to vibrate when being pressed down as there's not enough fluid in the M/C, which it did. Anyways, pressure was still there. Matthew supposed, one of the wheel cylinders is the cause of the leak, so he was so kind to get me four new cylinders for the front drums.
I changed all four cylinders, one wheel at a time with the brake pedal jacked to the floor. I had to disassemble the plate to get the cylinders out so I figured it'd be a good opportunity to clean out everything. Reassembled everything and was ready to bleed the brakes today. Started out with a pneumatic brake bleeder first, but it seemed to suck air on the bleeder screw, so I went on to the manual procedure and asked my gf to pump the pedal. Effed up again on the first try as I didn't tell her to hold the pedal pressed to the floor after pumping before I close the screw (dumb, I know). So I guess after bleeding all four wheels like that, there still got air sucked into the system. Started the whole procedure again with the RR wheel, then RL, then FR, then FL, until all valves came out clean (to my best knowledge). Filled up the M/C after each valve. Checked every valve for leaks and the system is dry. So I went on and started the engine to test pressure on the pedal - nothing (and of course no brake effect at all). Here's what I tried so far:
- recurring pumping of the pedal with engine off: no pressure/resistance
- recurring pumping of the pedal with engine running: no pressure/resistance
- I can see the booster moving when I press the pedal with the engine running. Since it worked two weeks ago, I'd suppose it's no vacuum problem. Engine idles slightly up when I press the pedal.
- However I detached the rubber hose from booster to reservoir and there was a "swish" sound, so that seems to build up just fine (put it back on afterwards)
I wondered if I should:
1. adjust the brake shoes via the screws at the back of the drum as explained in the manual
2. bleed again
3. could there be air in the M/C and if so, is there a way to bleed the M/C while on the car
Or anything else?
Since I couldn't find any leaks and it used to build pressure even with the leaking wheel cylinder, I'd guess, air in the system causes the pressure to fail. The two failed attempts to bleed the brakes properly might also have sucked air into M/C?!?
Would be grateful for any input! Thank you