Switched over to SS lines and have a slight trickle when bleeding the rears. Did some searching on some old threads and still cant figure it out. Cracked open the hard line on the rear on the MC and nothing flows. One thread said it may have shut off flow sensing a leak to the rear. Everything was fine before just a llittle soft. Any help would be appreciated.
Changed to SS brake lines
- Thread starter PRIME 1
- Start date
The master cylinder has shut off the rear circuit just as in when a cylinder is leaking. You'll have to center the piston ( open the port) by bleeding a front circuit just a little. This will move the piston in the master so the rear will open.
61porsche Just bleed a front line long enough for the rear portion of the master cylinder to be able to open; not cracked open. Steady on the pressure until you get all ports open.
I would appreciate understanding this a bit more. I think this might be the situation I have. I should open one of the bleeders on the front calipers? How do you know you have all ports open?
I would appreciate understanding this a bit more. I think this might be the situation I have. I should open one of the bleeders on the front calipers? How do you know you have all ports open?
The master cylinder shuts off a circuit that fails. Closes the port. It happens when you work on the brakes too, which may be the problem you have.
So in order to "reset" the master and open the circuit that you don't have fluid, you have to step back to the one circuit that is working and induce a small leak that moves the piston in the master cylinder so both ports are open. Crack or open that port or cylinder/ caliper. Then open the other side while gently pressing the pedal, power bleeder, etc.
Most do this procedure at the master where all the connections are located.
Sometimes the master is stubborn and hard to reset due to corrosion, dirt, etc.
There is a stop bolt on top of the master cylinder ( #2) above. Look below that bolt and the small circles are ports to the brake lines. If the rear failed, or was bled improperly the main pistons move and shut off. I've not done this on an E9, but on others had to physically move the piston over or use the pedal instad of a power bleeder which may not be enough pressure to move the cylinder to it's normal and open to the rear position. Otherwise you're rebuilding the master or replacing if it's really stuck closed.
So in order to "reset" the master and open the circuit that you don't have fluid, you have to step back to the one circuit that is working and induce a small leak that moves the piston in the master cylinder so both ports are open. Crack or open that port or cylinder/ caliper. Then open the other side while gently pressing the pedal, power bleeder, etc.
Most do this procedure at the master where all the connections are located.
Sometimes the master is stubborn and hard to reset due to corrosion, dirt, etc.
There is a stop bolt on top of the master cylinder ( #2) above. Look below that bolt and the small circles are ports to the brake lines. If the rear failed, or was bled improperly the main pistons move and shut off. I've not done this on an E9, but on others had to physically move the piston over or use the pedal instad of a power bleeder which may not be enough pressure to move the cylinder to it's normal and open to the rear position. Otherwise you're rebuilding the master or replacing if it's really stuck closed.
Last edited:
My Rear Port is the one that is not getting any flow. Both of my front ports have flow. So if I understand correctly. At the master cylinder crack open the hard line to one of the front calipers. Just open slightly? not remove? correct? Better to open one of the Bleeders at the caliper? Do I pump the brake? Then crack open the Rear Port? or Remove it from the MC? Pump the brake? Not sure how this all works but going to give it a try. Would appreciate any further directions. Thanks
Open slightly a front port/ line. Use the brake pedal maybe a third to half way down, which multiplies the force to move the pistons only until the rear opens. Then bleed normally form the rear to front.
Don't pump until after you get pressure. Don't go down all the way either which can stir up a bunch of crap in the MC.
Don't pump until after you get pressure. Don't go down all the way either which can stir up a bunch of crap in the MC.
OK. I tried this with no luck. I opened the drivers front inside caliper bleeder. I depressed my brake at got it flowing. I closed it down but still open just a bit and then opened my drivers rear caliper bleeder. I depressed, it had pressure so i slowly pumped the brakes but only about a quarter of the way. It is rather stiff but moves and makes a hessing noise. I did the a bunch of times but nothing out of the rear. I then closed up the front bleeder and tried again but still nothing. Was this correct?
Kinda. You can push farther just not all the way on the pedal. The theory is that there's some play in the rod/ linkage and you can get an air bubble or three by the kickback. Just don't push down all the way. Once you get some fluid out, close. Then press hard.
This last time try everything from the MC. Crack the line to a front. Press down the pedal most but not all the way in an effort to move the pistons in the MC. Close and press hard.
You can try to remove the stop bolt, use a small screwdriver, and push the piston to the front of the car if it's not seriously stuck. With the rear connection cracked, you should get fluid there after you put a bit back in the resevoir just by gravity.
If this doesn't work, your master cylinder is toast as the psitons are stuck / broken return spring/ corrosion on the piston, etc. closing off the rear. Rebuild or replace.
This last time try everything from the MC. Crack the line to a front. Press down the pedal most but not all the way in an effort to move the pistons in the MC. Close and press hard.
You can try to remove the stop bolt, use a small screwdriver, and push the piston to the front of the car if it's not seriously stuck. With the rear connection cracked, you should get fluid there after you put a bit back in the resevoir just by gravity.
If this doesn't work, your master cylinder is toast as the psitons are stuck / broken return spring/ corrosion on the piston, etc. closing off the rear. Rebuild or replace.
Did a bit more this evening. I checked port 5 at the mc. opened it up and pumped a few times and got fluid. Tightened it up and opened my bleeder at the rear caliper and pumped. It's still firm but nothing. What about the pressure regulator. Does it go out? I'm going to check the line from the mc to the regulator next to see if there is any fluid there. Have to do this over the weekend. Any other thought? I'm getting real frustrated over his. I want to get it fixed so I can drive my car!!!
It's actually a pressure limiter, but only after moderate pressure. It bypasses part of the pressure so the rears don't lock up prematurely.
I've only heard of a leak on that item, and looking at the adjustment curve; it's not much. If it is the problem, White Post Restorations can rebuild it.
Try the main line to the pressure limiter by cracking the connection to make sure you've got fluid/ pressure there. Follow the line out to make sure nothing got kinked and pinched off.
Here's a little info-http://weboldtimer.com/index.php?option=com_content&view=article&id=61&Itemid=72&lang=en
I've only heard of a leak on that item, and looking at the adjustment curve; it's not much. If it is the problem, White Post Restorations can rebuild it.
Try the main line to the pressure limiter by cracking the connection to make sure you've got fluid/ pressure there. Follow the line out to make sure nothing got kinked and pinched off.
Here's a little info-http://weboldtimer.com/index.php?option=com_content&view=article&id=61&Itemid=72&lang=en
Last edited:
Yes, those guys seem serious. But they don't talk pricing either.:shock:
My research on the valves also shows that 1998-2000 Mini Coopers had a very similar valve. Those are available new from GB. But each valve had a specific pressure ( bar) rating per application. Since it's a linear action, I don't think you can substitute something like a Wildwood product without it acting full time.
It would be interesting to hear from coupers that may have experienced a tail slide from a lock up. I've never seen or heard of that.:?: Usually, powering through it is the best action.
My guess is that the valve is a an early attempt at ABS theory since electronics were being introduced on high end cars of the time.
My research on the valves also shows that 1998-2000 Mini Coopers had a very similar valve. Those are available new from GB. But each valve had a specific pressure ( bar) rating per application. Since it's a linear action, I don't think you can substitute something like a Wildwood product without it acting full time.
It would be interesting to hear from coupers that may have experienced a tail slide from a lock up. I've never seen or heard of that.:?: Usually, powering through it is the best action.
My guess is that the valve is a an early attempt at ABS theory since electronics were being introduced on high end cars of the time.
Did a bit more investigative work today. I trailed back to the pressure limiter and found fluid. Coming out to the line that goes to the caliper. So I've isolated this problem to between the limiter to the caliper. I want to now check the rubber hose but want to know what direction I should be turning to remove the metal tube from the rubber. If the rubber tube is stationary do i turn the metal tube fitting counter clock wise. I try and its tight and do not want to mess up the head by forcing and stripping. Any advise