Help on Bleeding Brakes

[nvbass]

Im trying to bleed the brakes on a 87 325i and am having troubles. The car was sitting for years, I got it running, but the brakes were VERY soft - to the point of having to use the e-brake to stop the car (i only drove the car down the local street and back). One of the front caliper bleed screws was broken so i decided to replace both front calipers to ensure I would get equal braking at the front. On to the bleeding... the RR was tough to get going, but after a few extra brake pumps from my helper we were able to push some cruddy stuff out of the bleed screw and it seemed to be working fine. The LR will not bleed, no fluid comes out at all. I even disconnected the hard line that connects to the rubber line running into the caliper and nothing came out of that location either. Same issue with RF, no fluid coming out. LF bleeds fine.

To recap, RR and LF push out fluid, LR and RF have no signs of fluid. Any ideas?? Clogged lines, bad master cylinder, bad ABS pump?? Can I remove the hard lines from somewhere to blow compressed air through to check for blockage?

Im fairly new to the E30 restoration so any help would be greatly appreciated.

[nvbass]

I forgot to mention and Im not sure if its relavent. But the brake pedal is really firm since i've started trying to bleed the LR and RF (screws that do not push out fluid). The pedal is easily pumped when i have one of the other screws open (the ones that do push out fluid).

[Dakotademon7]

The first think you should of done was to flush out the old brake fluid. You will have to investigate the reasion your not getting fluid threw all your lines. On the blocked lines, you will have to disconnect at each connecting starting at the wheel till you find fluid flow. Then you will have to carfully inspect the line from the point of flow back to the wheel. It could be some built up junk inside the line or there could be a spot where the line is pinched closed.

[jlevie]

It will help to understand how the brake system is set up. There is a single line from the ABS unit that goes through the bias valve and to the rear of the car. It splits at a tee above the rear subfame with short soft lines there and then goes out to each wheel to a soft line and then the caliper. Since the RR bleeds but the LR doesn't, the system has to be good at least to the tee. And since there was no flow when the outer soft line was disconnected, the blockage has to be between the tee and the outer soft line. Probably at the inner soft line.

Each front caliper is a separate line from the ABS unit. So the components of each front brake are the two valves in the ABS unit, the hard lines to each side of the car, and the soft lines to the calipers. Crack the RF line at the ABS unit and see if there is flow there. If there is, the problem is in the line to the caliper. If there isn't, the valve in the ABS is stuck. Which means replacing the ABS unit.

[nvbass]

Thanks to both of you for the advice!