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Rear Brakes not bleeding


Doug DiPaola
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Hi All. ‘71 2002. So, after finishing  complete brake job of all brakes, today I added brake fluid and started the bleeding process. We started at the right rear and followed process outlined by hegedus dated 1/4/2013. Result: no brake fluid; from either side, from rear bleeder screws.(new wheel cylinders) Jumped to front right and got fluid from top bleeder screw. Same front left.  Could a defective  master cylinder provide fluid  pressure to the front but not to the back? Or is presence of  pressure/fluid to front indicate a working master cylinder? I inspected the metal line servicing the rear brakes from master cylinder to rear junction where splits to each wheel cylinder. The metal line doesn’t show any crimps or kinks or any signs of leaking fluid.  Any thoughts on what the issue is would be appreciated. Thanks very much. EDIT- after pumping pedal for awhile, it did not appear that fluid level in reservoir did not change

Edited by Doug DiPaola
EDIT fluid level
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The presence of fluid coming out of the front brakes is a good indication the the master cylinder is just okay.

 

Sounds like you gotta keep pumping. It takes a while for fluid to run from the fluid reservoir in the front to the rear brakes. 

EDIT: Is the fluid level going down as your pumping and waiting for excess fluid to escape the back brakes?

Edited by Krynvel
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15 minutes ago, Doug DiPaola said:

Hi All. ‘71 2002. So, after finishing  complete brake job of all brakes, today I added brake fluid and started the bleeding process. We started at the right rear and followed process outlined by hegedus dated 1/4/2013. Result: no brake fluid; from either side, from rear bleeder screws.(new wheel cylinders) Jumped to front right and got fluid from top bleeder screw. Same front left.  Could a defective  master cylinder provide fluid  pressure to the front but not to the back? Or is presence of  pressure/fluid to front indicate a working master cylinder? I inspected the metal line servicing the rear brakes from master cylinder to rear junction where splits to each wheel cylinder. The metal line doesn’t show any crimps or kinks or any signs of leaking fluid.  Any thoughts on what the issue is would be appreciated. Thanks very much. EDIT- after pumping pedal for awhile, it did not appear that fluid level in reservoir did not change

 

Does it have the original soft lines in the rear? They could have swollen shut over time. 

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If while bleeding when you press the brake pedal and it goes to the floor, then that fluid is going SOME where.  And if it's not coming out of the open bleeders, then it's most likely because there's just more air in the lines that it is still displacing.  Could also be leaking out somewhere, so check for dribbles, or *maybe* the fluid movement is being absorbed by the flexible lines, but I think this unlikely, because the pedal would feel a LOT different (firmer) than normal with the bleed valves open.

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Big confession. I looked at rear flex lines at the get go of the whole brake rehab project and thought I should replace but thought they looked sound; no leaking or weeping at fittings and no cracks; but damn, they looked like a pain to replace. I will pursue “ Flexis Linus Occlutionus “ as the probable diagnosis and disconnect them on the forward side and see what happens. Thanks all.

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1 hour ago, Doug DiPaola said:

they looked sound; no leaking or weeping at fittings and no cracks;

Thats the issue: they look OK from the outside, but the inside is swollen/constricted so they either dont pass any fluid or act as some one-way valve causing brakes to drag. If they are of unknown age, then replace... they are a common metric hose, sames as other european cars of the period (VW, Volvo, BMW etc)

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Thanks for help with my non bleeding brake lines. As I had expected it was a challenge getting the rear flex lines off. It has been days of attempting with lots of PB Blaster and awkward wrenching. The threaded bit that is at the end of the metal “branch” pipe that rotates around the pipe was/is seized to the pipe. With the 14mm end of flex line secured, wrenching on the swivel 11mm threaded end of metal pipe resulted in pipe starting to twist, risking crimping pipe; that happened when replacing wheel cylinders. Last night I got a thought that if I could introduce a significant amount of vibration to the seized connection it might free up. So, I got my multi tool with the oscillating cutter head attached. The standard blade wouldn’t reach the fitting. I didn’t want to cut the fitting, just vibrate the side of the blade against the fitting. I PopRiveted a small sawzall blade to the stock blade to get the reach. I ground off the teeth to prevent cutting. The video shows the rig in operation. I went back and forth between the two side; applying the vibration then some BPBlaster. The result was that the swivel bit on end of metal pipe still was seized to pipe and would not rotate but, I was able to just reach around to the flex hose and unscrew it no wrenching needed. Pumping brake pedal shot out fluid from both sides. I tried to stick a thin rigid wire into the flex hose but both were thoroughly blocked. Waiting for new flex hoses to arrive to move forward. Thanks again.

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For what it's worth, when I replaced all my flex lines, calipers and wheel cylinders, enough air got into the system that I was unable to get any fluid to emerge from the rears until I partially bled the fronts. So I started at the front and then went to the rear and did the "classic" flush/bleed, ending with the fronts again.

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Not a bad idea with the oscillating tool. I had similar issues with my rear lines. after soaking in PB Blaster and lots of struggling and cursing like a sailor, I finally cut of the rubber hose and put a long socket over the whole metal fitting and a wrench on the metal line side wedged against something to stop it from twisting. That finally worked, if I had to do it again I'd start with the way I ended up doing it. On the front lines I was not so lucky and stripped one of the metal line nuts from the caliper to the flex line, had to find a replacement.

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