Passat 91 rear brake problem

[figaro]

Hi,
i'm new to this forum and you guys are my last chance to fix my car. I changed both my front and back brake pads. After i changed the front one, no problem good pressure, everything is OK. However, when i changed the rear brake pads i have no more brakes at all. I can stop only with handbrake. Tried to bleed some brake fluid, pumped the brake more than 40 times - nothing happens no pressure on the rear brakes at all. I decided to rush and buy new calipers. Changed them both and still have the same problem. Any suggestions? Thank you for your time and consideration.

[boschmann]

Make sure the master cylinder reservoir is full first. Then try an alternate bleeding method or pressure bleeder. Try bleeding at the master cylinder first. Then you can have someone push the pedal to the floor, open a rear bleeder then close the bleeder, then have them release the pedal & wait about 5 seconds before holding the pedal to the floor again. Repeat until some fluid comes out under pressure then go back to the normal method. If no fluid ever comes out or no pressure builds then suspect the master cylinder.

[figaro]

Thank you for the ultra fast reply. However, i've tried this already. What i did was i went in front, opened the four brake lines on the master cylinder itself and asked my girlfriend to pump the brake. The pressure is excellent. I suspect that it might be the small pressure regulator on the back next to the exhausting pipe since when i bleed the front the pressure is good but once i start bleeding the rear no fluid comes out, or just some drops. Lines are checked, no leaks anywhere. I hope that should be it. Do you have any other suggestions? Thank you for your time and consideration again. You guys are great.

[boschmann]

If there is no fluid coming out of the lines at the master then suspect the master. What I was trying to describe was a slightly different approach to bleeding. Open only one rear line, then push the pedal to the floor (no pumping), close the valve or line, then release the pedal & wait a few seconds before opening the valve and having them push the pedal to the floor again. Repeat until fluid sprays out. Then you can return to the pumping method. Actually, you shouldn't pump the pedal with the lines open as you described. Pump the pedal a few times then open one line or valve, after closing the valve it is safe to release the pedal & pump again.

[figaro]

I tried that as well it didn't work. I took out the four brake lines from the main cylinder and asked again my girlfriend to pump the brake. Brake fluid is coming out from the master cylinder and there is pressure. What i saw is broken is the vacuum pipe with check valve(the small plastic part situated on top of the master cylinder). Maybe because of it there is not enough pressure in the system. Do you thing that might be the problem.

[boschmann]

That sounds like the booster vacuum supply, without it the brakes will seem excessively hard to press (no power assist), not spongy. As I stated don't try opening more than one line or valve at a time or bleeding will not be correct. Check for pressure one line at a time. Once pressure is at the master then move to the rear valves. Find where the pressure gets to, see if it makes it past the proportioning valve you describe in your second post.

[figaro]

Finally fixed my car, it turns out all this time i was looking @ the wrong direction. The master brake cylinder was the problem so i just replace it today. Everything is Ok now. Thank you for your support.