Losing pressure on brake pedal

[GIANUCCI E30]

What's up ladies and gents. I have a problem going on with the my 89 e34 535/5 and I hope someone can help.


:help Ok, I just replaced my slave cylinder on my car because I was having issues with the clutch. I bled it and it works perfect without fail. However since I did that my brake pedal is now giving me the blues. After riding around town last night the brake pedal lost pressure. It would engage. However I damn near had to push it to the floor.:censored:

Funny thing is.... that this morning when I planned to put it in the air to check if I had tighten down the line and bolts connecting to the slave cylinder. Like magic...PRESTO!!! I have pressure on the brake pedal like nothing happened. I did still check the line and the bolts everything is good. Let me know guys. Thanx.

[dansgt]

either had a lil air in the line that worked itself out, or your master cylinder's failing. i'd bleed the system and see what happens if it does it again.

[GIANUCCI E30]

UPDATE

DansGT: I gotcha. :D Yeah I'm gonna bleed the system again. See if that works.

It feels like a air problem only because it did it again this afternoon on my way to work (got to get the holiday overtime). However once I hit the highway and got it up to 80mph then slowed down to pay a toll (yeah, average speed on certain GA highways :evil2 ) It came back.

I did notice is that my Brake fluid light came on after start up. But once I started rolling out of my complex it eventually went out. Also I saw a bit of smoke coming from the rear driverside wheel when I arrived at the job. Though the car doesn't feel like the brakes are holding it back. I'm hoping it's not a stuck caliper. As easy as it is to get it back down, It's a bother. Especially if the seal is busted on the caliper. I'll keep you informed.

[GIANUCCI E30]

UPDATE:
I'm going to give all the details and findings so I don't and ya'll don't miss a thing. I think from looking at the system. My master cylinder is shot. Here are the things observed and experienced through the pressure drop down to having zero stopping power:

Brakes are still not 100%. Yesterday they when to 0%. Pedal going to the floor. No stopping power unless I gear her down to 1st then apply e-brake.

Bled the system.

The front driverside caliper skeeted out a little dribble then nothing. Pressure began to build but not much.

The rear passenger caliper was as dry. Meaning I unscrewed the nipple out of the caliper and it was white and dry. no pressure.

My pedal is going to the floor with little to no resistance with the car on.

Car off the pedal gets tight.

The expansion tank for the hydro fluid had a bad hose end. I cut it off and
re-attached hose. In process the tank popped off. I re-attached tank and proceeded to try and bled system.

pedal still goes to floor.

Any suggestions???

[ShapeShifter]

I have a good brake master and booster for $90.

[GIANUCCI E30]

I have a good brake master and booster for $90.

:buttrockhow much shipped? I need them here like yesterday.

[ShapeShifter]

$100 shipped.
I can get it to fedex tonight.
I'm going there to drop off some other things for
board members.

[GIANUCCI E30]

I have a good brake master and booster for $90.

This maybe a dumb question but I have to ask anyway. Don't like having my baby down for too long. She gets upset.

question: I realize that some BMW parts are car specific. Are the booster and master cylinder different per car? (ie: 535 vs. 525 or auto vs stick) or are they all the same?


I have a good brake master and booster for $90.

I'm with you dude I need the pay pal info but I want to be sure.

Ok even though my clutch is good (changed the slave before all this started to happen) and no lines or hoses are leaking. My thought was correct? The master cylinder & the booster are shot?

Last question. How do I get access to the bolts holding the entire thing on? Yes I have a manual (its a haynes...but it does the job) But does anyone have a couple tricks on how to get the sucker out I'm all ears.

[GIANUCCI E30]

Update:

After conversing and and taking a deep breathe I fixed my issue. It was the Master Cylinder. However I realized I was misinformed. I was under the impression that the master cylinder is part specific. Meaning, (in my case) If you have a Girling setup. You need a Girling Master Cylinder. This is incorrect. With a little modification and line adjusting you can put a different M.C. in your E34.

I was lucky enough to get my M.C. from a local guy who gave me all the lines from the Cylinder to the ABS unit. He has tons of parts for e34s so if anyone needs anything I'll get you to him. (Hes a stand up guy, honest and quick.)

He had a Lucas unit, I had a Girling ( I already mentioned that)
I had to reuse the line closest to the booster from the girling unit to get it to mate up properly. However I had to adjust the new line closest to the front of the car so that it could fit the ABS Unit.

After that I bench bled the M.C. (didn't really need to it was good to Go) Bled all four calipers. Fired her up, Hit the brakes....We got brakes. Thanks to everyone for their help.