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> Brake bleeding, Nothing but air from rear brakes
Medtner3
post Oct 4 2020, 07:49 AM
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Just rebuilt my rear calipers with seals from PMB Performance. Using a vacuum brake bleeder I started with the right rear caliper lower bleeder screw ( I have two screws) and initially pulled about an inch of brake fluid with lots of bubbles and then zip. I get zero brake fluid now.

What could cause this? I have no signs of any leaks and the brakes were not bad before I rebuilt the calipers. I read somewhere that I might need to bleed the proportioning valve or even pump into the caliper some brake fluid through the top bleeder ?

I ordered a Motive pressure bleeder which arrives in a few days


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davep
post Oct 4 2020, 08:55 AM
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On a caliper with two bleed nipples, the top is the bleed, and the bottom is a drain; only bleed with the top nipple. Air bubbles rise you know.
When bleeding the system, keep checking the reservoir to be sure it is full by removing the cap and looking down inside. The reservoir is divided by a half barrier into front & rear so an external glance may not reveal that the other half is empty. If a half does empty, then you will have to do a long bleed to ensure any air introduced at the reservoir is removed.
Pedal bleeding ensures that high pressure is able to be achieved, and it also crushes bubbles and helps them move through the system; keeping them from being trapped within things like the pressure regulator. So I like to finish a bleed with pedal bleeding after using either a vacuum bleed or an air pressure bleed method.
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Medtner3
post Oct 4 2020, 11:51 AM
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QUOTE(davep @ Oct 4 2020, 09:55 AM) *

On a caliper with two bleed nipples, the top is the bleed, and the bottom is a drain; only bleed with the top nipple. Air bubbles rise you know.
When bleeding the system, keep checking the reservoir to be sure it is full by removing the cap and looking down inside. The reservoir is divided by a half barrier into front & rear so an external glance may not reveal that the other half is empty. If a half does empty, then you will have to do a long bleed to ensure any air introduced at the reservoir is removed.
Pedal bleeding ensures that high pressure is able to be achieved, and it also crushes bubbles and helps them move through the system; keeping them from being trapped within things like the pressure regulator. So I like to finish a bleed with pedal bleeding after using either a vacuum bleed or an air pressure bleed method.


Okay the first problem was my master went dry because it was so discolored from ATE super blue that I thought it had fluid. How do I bleed now .. do I need to bleed the master?
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iankarr
post Oct 4 2020, 12:08 PM
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QUOTE(Medtner3 @ Oct 4 2020, 01:51 PM) *

QUOTE(davep @ Oct 4 2020, 09:55 AM) *

On a caliper with two bleed nipples, the top is the bleed, and the bottom is a drain; only bleed with the top nipple. Air bubbles rise you know.
When bleeding the system, keep checking the reservoir to be sure it is full by removing the cap and looking down inside. The reservoir is divided by a half barrier into front & rear so an external glance may not reveal that the other half is empty. If a half does empty, then you will have to do a long bleed to ensure any air introduced at the reservoir is removed.
Pedal bleeding ensures that high pressure is able to be achieved, and it also crushes bubbles and helps them move through the system; keeping them from being trapped within things like the pressure regulator. So I like to finish a bleed with pedal bleeding after using either a vacuum bleed or an air pressure bleed method.


Okay the first problem was my master went dry because it was so discolored from ATE super blue that I thought it had fluid. How do I bleed now .. do I need to bleed the master?

I would. Since it's gone dry, i'd just start from scratch...

– Bleed the master (in the car is fine...see video link above). Use pedal only...and put a block or something down to make sure you don't hyper-extend the pedal and damage the seals inside the MC). When no bubbles are coming through...

– Put a quart of fluid in the motive, hook it up and pressurize to 5-10 PSI. Use a rubber mallet to rap on the caliper and dislodge air bubbles while bleeding.

– Bleed from the top screws LR, RR, RF, LF.

– Finish with a pedal bleed all the way around.

If you don't have a firm pedal, do it again until you do. If it's firm enough to drive, but not perfect, that's kind of typical. Just carefully drive it on a bumpy road for a bit, then bleed again.

Good luck and be safe!
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Posts in this topic
Medtner3   Brake bleeding   Oct 4 2020, 07:49 AM
mlindner   Chances are the brake fluid drained out of the mas...   Oct 4 2020, 08:06 AM
Medtner3   Chances are the brake fluid drained out of the ma...   Oct 4 2020, 08:25 AM
mlindner   Yes I would try the fronts first...I know that is ...   Oct 4 2020, 08:36 AM
Medtner3   Yes I would try the fronts first...I know that is...   Oct 4 2020, 08:42 AM
davep   On a caliper with two bleed nipples, the top is th...   Oct 4 2020, 08:55 AM
Medtner3   On a caliper with two bleed nipples, the top is t...   Oct 4 2020, 11:51 AM
iankarr   On a caliper with two bleed nipples, the top is ...   Oct 4 2020, 12:08 PM
Medtner3   [quote name='Medtner3' post='2856582' date='Oct 4...   Oct 4 2020, 01:42 PM
Medtner3   [quote name='Medtner3' post='2856582' date='Oct 4...   Oct 6 2020, 04:28 PM
Olympic 914   It only pressurizes to 5-6 psi I wonder if tha...   Oct 6 2020, 06:42 PM
Medtner3   It only pressurizes to 5-6 psi I wonder if th...   Oct 6 2020, 06:47 PM
iankarr   [quote name='Olympic 914' post='2857140' date='Oc...   Oct 6 2020, 07:59 PM
Tdskip   The other thing that I would add is that for whate...   Oct 4 2020, 10:55 AM
iankarr   I like to use pressure (motive @ 5-10 psi) followe...   Oct 4 2020, 11:12 AM
rhodyguy   Get some speed bleeders. One for each caliper. Ins...   Oct 4 2020, 12:05 PM
Gint   Get some speed bleeders. One for each caliper. Ins...   Oct 6 2020, 04:45 PM
Amphicar770   I had no luck vacuum bleeding the 914, couldn...   Oct 6 2020, 05:19 PM
Medtner3   I had no luck vacuum bleeding the 914, couldn...   Oct 6 2020, 06:49 PM
rjames   I could never get the brakes bled properly until I...   Oct 7 2020, 11:07 AM
Medtner3   I could never get the brakes bled properly until ...   Oct 9 2020, 05:17 PM
draganc   Assuming you are not in a rush to drive the car I ...   Oct 8 2020, 05:38 PM
Medtner3   Damaged master cylinder or impatient? I put on spe...   Oct 8 2020, 07:13 PM
davep   Have you correctly set the venting clearance on th...   Oct 8 2020, 08:09 PM
Medtner3   Have you correctly set the venting clearance on t...   Oct 9 2020, 07:27 AM
Gint   Have you correctly set the venting clearance on th...   Oct 10 2020, 09:55 AM
Medtner3   [quote name='Medtner3' post='2857647' date='Oct 9...   Oct 11 2020, 08:30 PM
Medtner3   UPDATE: Pedal bled four times have a pedal now it...   Oct 9 2020, 05:19 PM
Frankvw   I understans it is very frustrating yes. Keep up t...   Oct 10 2020, 06:44 AM
davep   http://www.914world.com/bbs2/index.php?showtopic=3...   Oct 10 2020, 09:27 PM
mb911   Kind of have the same issue.. The entire brake sys...   Oct 11 2020, 06:36 AM
iankarr   Kind of have the same issue.. The entire brake sy...   Oct 11 2020, 07:08 AM
mb911   Kind of have the same issue.. The entire brake s...   Oct 11 2020, 07:10 AM
Medtner3   [quote name='iankarr' post='2858075' date='Oct 11...   Oct 11 2020, 08:31 PM
Medtner3   [quote name='iankarr' post='2858075' date='Oct 1...   Oct 11 2020, 08:33 PM


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