HELP! Brake bleeding problem in e34 530i

[4dri4n]

Help!

I replaced the 4 calipers to the car because the donor car had no rust in them and I was cautious not to get air into the system. But some air went in. Anyways I went for a ride and the car slowly had some braking resistance until I wasnt able to move it without giving a lot of gas.
The thing is that the front gets pressurized and the rears dont. I am unable to bleed the rear calipers. I can loosen the brake line and push the pedal and no brake fluid will come out. However the fronts will get locked until I relase pressure by loosening the bleed plug.

Do you know what to do with this? I am lost.

[moroza]

Does the car have ASC? If so, you may need to take it to a dealer for a special machine to open the valves. Or delete ASC like I did.

[4dri4n]

How do I know if it is equiped with ASC? I dont know but my guess is no...
If it does have ASC, how do you delete the ASC?
Cause I am gonna fit an LS diff and this could be a problem. I would say I dont have ASC in my car but I am not sure.
I dont understand why the rear calipers are not getting fluid. It is like when I push the brake pedal something gets pressurized and then the front brakes are unable to retract and the rear brakes dont even do nothing. I could just leave the brake line disconected from the rear caliper hanging around and not a single drop of brake fluid would come out even when the front are still pressurized.
There must be something wrong with the brake proportioning valve or something.

[demetk]

Could be that the ABS unit has plugged lines. You can test by cracking each input and output line open and seeing if any fluid comes out. I had blocked rear lines and found the blockage at the rear output lines at the ABS unit. Found another used one and the problem was solved. You can disassemble the ABS unit and clean it out. Not sure if there is a writeup on this forum but there is a writeup on MyE28, http://www.mye28.com/viewtopic.php?f...09879&start=25.

[The Chauffeur]

Could be that the ABS unit has plugged lines. You can test by cracking each input and output line open and seeing if any fluid comes out. I had blocked rear lines and found the blockage at the rear output lines at the ABS unit. Found another used one and the problem was solved. You can disassemble the ABS unit and clean it out. Not sure if there is a writeup on this forum but there is a writeup on MyE28, http://www.mye28.com/viewtopic.php?f...09879&start=25.

+1

The ABS unit is notoriously difficult to purge; it happened to me when I replaced the master cylinder and tank grommets; the only thing that did the trick in my case was a "one man bleeder", but look for one with a check valve, like this:

s-l1600[1].jpg

[4dri4n]

Do you know if the ABS module is the same on a 530i v8 and a 525i m50tu?
If the are the same I may consider swapping them and maybe the problem is solved. I will try to bleed the brakes again on wednesday and we will see... I bought a vacuum bleeder. Hope this thing will do the job.

[moroza]

Do you know if the ABS module is the same on a 530i v8 and a 525i m50tu?

I use RealOEM (mostly) to answer questions like this.

[ross1]

If the calipers were full of rust there is a good chance the lines have some too. I've seen them blocked by rust.

[401michael]

I know some cars you need to unplug the connector from the abs unit to bleed the brakes, but I have never bled the brakes on my bmw there should be something in the bentley manual if you have one.

[ross1]

Do you know if the ABS module is the same on a 530i v8 and a 525i m50tu?
.

Do you mean the pump? They have different part numbers, still might interchange though.
IF per chance you need PN 34 51 1 160 006 Bosch # 0-265-201-032 I have it and will offer it for the cost of shipping. Removed looong ago from a '94 530/5 GE53250 and sitting on a shelf for a decade or so.

[4dri4n]

It is imposible to disassemble the ABS module. There is no way to do it. It is no way similar to that on mye28 pics. That said, I removed the brake master and flushed with vacuum all the lines. I noticed that the reason why no brake fluid was coming out of the rear calipers was because the pedal did not went up to its resting position. Instead it was half way of its stroke closing the window that allowed brake fluid to go into the master. Once I pulled up the brake pedal, it immediately started to flow.
Now, what makes me feel intrigued is why the heck it didnt come back up to its resting position on its own. I pulled out again the brake master to see if there is something wrong with the vacuum actuator and it seems it does. Wirhout the brake master, once I depress the brake pedal it wont come back again. I have to assist it pulling from it. Is this a normal thing? Is it possible that my brake booster is fucked up? Should it move freely without ressistance?
Im gonna try and bleed it now and we will see, but it seems strange to me...

[Sleepyhead97]

4dri4n, have you had any luck on this? I am experiencing the same issues. I have not taken anything apart to look yet. I was planning on starting at the rear lines and work my way to to the abs unit/master cylinder. I saw another thread that mentioned the grommet material deteriorating at the master cylinder and clogging up the rear lines.

[Sleepyhead97]

Update on my situation. Turned out the calipers were gunked up. I took bleeder screw out did not bleed.

Ended up removing the caliper (only took 5 mins) and sprayed brake cleaner in there. (Yes I know it's bad) anyways got allot of rust out and it bleeds fine..

I did same thing to other rear side. No issues. I bleed them out well... Used one man bleed procedure on all four wheels.

I accidentally bled the first corner dry, but surprisingly did not mess up abs.
I got pretty lucky through it all..


So I bed the pads in afterwards, and I can conclude only my front brakes worked before this procedure. Now it stops so much easier after procedure.