no pressure on power brakes
-
eddie.gordou
- Posts: 25
- Joined: Thu Apr 06, 2006 5:01 am
- Location: Düsseldorf, Germany
- Contact:
no pressure on power brakes
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
Born to roll...
-
RICKYMOPAR
- Posts: 530
- Joined: Wed Mar 11, 2009 9:58 pm
- Location: Broomfield, Colorado
Re: no pressure on power brakes
Eddie, I noticed years ago our replacement front brake cylinders came with newer cups and pistons not like the original fluted O ring around the piston. These do work but have a tendency to trap more air than the old system. I found that if I back off the brake adjustments completely, this leaves no room in the brake cylinder to trap air during the bleeding procedure. pump the pedal slowly to avoid foam or trapping air in the new fluid. Readjust your brakes after bleeding. see if this helps.
-
eddie.gordou
- Posts: 25
- Joined: Thu Apr 06, 2006 5:01 am
- Location: Düsseldorf, Germany
- Contact:
Re: no pressure on power brakes
Thanks Ricky! I went on to adjust the brake shoes on all four wheels today and as far as I was able to test it in the garage, the brakes are back! As there was no effect at all before, brakes are working again now. Will do some extensive testing to make sure the brakes do what they are supposed to.
First I took off the front drums again, just to check if there are any leaks and took a video of each of them to see if they work while I stepped on the pedal. All good so far. Then I adjusted front and back drums. As I bled them twice on Sunday, I figured I'd try adjusting first and if it hadn't worked, I would have bled again. Guess it may have been the brake shoes instead of air in the system. One general question: If there would be air in the system, wouldn't the brakes work at all or just loose strength? I was just wondering, how you figured out, what effect some or more in the system has on the failure of brakes...
First I took off the front drums again, just to check if there are any leaks and took a video of each of them to see if they work while I stepped on the pedal. All good so far. Then I adjusted front and back drums. As I bled them twice on Sunday, I figured I'd try adjusting first and if it hadn't worked, I would have bled again. Guess it may have been the brake shoes instead of air in the system. One general question: If there would be air in the system, wouldn't the brakes work at all or just loose strength? I was just wondering, how you figured out, what effect some or more in the system has on the failure of brakes...
Born to roll...