Once you get air in the ABS pump it's a pain to bleed. What you have to do is activate the pump and bleed while it's running.

You might try this: jumper the ABS Valve relay and pressure bleed the brakes while the pump is running. I'd jumper it for only brief intervals, say 15-20 seconds at a time. The relay should be located behind the kick panel in the left front footwell.

Alternately, I've heard of people locking up the brakes on dirt roads and then bleeding the brakes to purge the air.

 

Any answers I just replaced all 4 pads and rotors and I'm having my pedal not fully retract? I have the auto slip control and traction control but the light is on and dash says brake linings still. I assume that is from either the front or rear pad wear sensor. Any good code readers out there under $150 for a 94 530i ?

 

How will locking the brakes on dirt road help ?

 

Just to clarify, your brake pedal is not coming back to the position it would normally be in if you didn't have your foot on it? Do the brakes feel firm, or does the pedal have a lot of give?

If your pedal is not coming back up, I'd be worried about the master cylinder. It has a spring in it that should return the pedal to proper position.

If you brake hard on a surface with fairly low traction, like a dirt road, your ABS pump should activate. That combined with the hydraulic pressure from braking should eventually work out any air bubbles trapped in the ABS unit.

The better alternative would be to rig up a jumper wire with a switch that would let you activate the ABS pump by bridging the power connection at the valve relay (it's behind the kick panel in the driver's footwell). Then I'd pressure bleed the system using a Motive power bleeder or equivalent. I would turn on the ignition, place the brake fluid reservoir under pressure, activate the ABS pump and open a bleeder screw while the pump is running. You don't want to run the pump too long, maybe 20-30 seconds at a crack.

 

The pedal won’t return fully the more I use it the more it sticks. I can manually return the pedal by moving the linkage in between the fire wall and booster. Or pulling up with my foot. And when I bled some old fluid out manually it was fine for about 20 miles. (No sticking)Brake pedal is some what firm but not 100%.


Sent from my iPhone using Bimmerfest

 

Pic of booster connection

Sent from my iPhone using Bimmerfest mobile app

 

Bad master cylinder, most likely.

 

http://www.realoem.com/bmw/enUS/showparts?id=HE13-USA-04-1994-E34-BMW-530i&diagId=35_0055
Compression spring ? Maybe
http://www.realoem.com/bmw/enUS/showparts?id=HE13-USA-04-1994-E34-BMW-530i&diagId=35_0161
Retainer spring ? - can I take the slack out by adjusting the linkage ?
http://www.realoem.com/bmw/enUS/showparts?id=HE13-USA-04-1994-E34-BMW-530i&diagId=34_0462
Master cylinder
http://www.realoem.com/bmw/enUS/showparts?id=HE13-USA-04-1994-E34-BMW-530i&diagId=34_0392
Booster

Sent from my iPhone using Bimmerfest

 

From 1000 miles away, without any way of looking at the car, my best guess is the master cylinder.

 

Lol thanks 80 new master cyl from Germany I guess I'll replace my clutch also (sitting in the car)as I took the panel off to look at pedal system and maybe toss in a solid steering bushing

Sent from my iPhone using Bimmerfest mobile app

 

Hope you can find someone close to home to confirm that. Do the wheels get hot or lock up when the pedal sticks? That would support my wild-a$$ guess.

If you're going to DiY, may I recommend this reverse brake bleeder: https://express.google.com/product/1267156024298829172_15123433977816587425_3103314?mall=WashingtonDC&directCheckout=1&utm_source=google_shopping&utm_medium=product_ads&utm_campaign=gsx&gclid=Cj0KCQjw6fvdBRCbARIsABGZ-vTEzGOOB1dPnGPRuw-ZYZpOM5pG_XvNnbivuxZqlCo7jJGT6GBq_lwaAtedEALw_wcB It's pretty neat, pushes brake fluid into the system through the bleeders at the wheels. If you don't have any air in your ABS pump, this will keep it out if you use it right.

I just replaced a master on a Ford Ranger; bench-bled it, of course, and then used the reverse bleeder to power bleed at the wheels instead of at the reservoir. The bleeder is a lot of money for a few pieces of plastic, but it worked like a charm. I'm sold on it.

 

Nothing is getting excessive heat. When the pedal sticks the brakes act like I’m depressing the pedal... so the brakes are working. Just sticking on once pressed. It rained tonight did a couple parking lot abs lock ups (dirt road) method. Gonna attempt to bleed again and go from there.

Never had any abs brake systems fail on me before. This is all new to me besides pads and rotors bleeding.


Sent from my iPhone using Bimmerfest

 

UPDATE:

So I finally fixed my issue by replacing brake booster and master cylinder then used a wire to jump the ABS pump into action and at that moment I felt the solenoid valves all cycle up and down.

Did that 2 more times not more than 10min and now bled the whole system a fresh. So far no braking issues whatsover, great pedal travel and feel.

Brakes work fine and hold hold and retract, did dirt track emergency braking and everything was fine.

Sent from my SAMSUNG-SM-G870A using Tapatalk

 

Good to hear you worked it out.

 

Did you take apart the master and the booster to find what fails ? Did you find a cause of the problem?

I bled my brakes again still had the pedal not return fully. But while car was in the air I just put it in first gear and started tapping the brakes to see if it would stick and the pedal returned fully. Test drive and it haven’t hung up yet ***129310;***127995;. Deff had some more air in the lines. I Activated abs by locking up on wet road before second bleed.

I just hope it doesn’t stick any more


Sent from my iPhone using Bimmerfest

 

Did you take apart the master and the booster to find what fails ? Did you find a cause of the problem?

I bled my brakes again still had the pedal not return fully. But while car was in the air I just put it in first gear and started tapping the brakes to see if it would stick and the pedal returned fully. Test drive and it haven't hung up yet ***129310;***127995;. Deff had some more air in the lines. I Activated abs by locking up on wet road before second bleed.

I just hope it doesn't stick any more

Sent from my iPhone using Bimmerfest

Yes, I did and found that the push rod that goes from the brake booster to the brake pedal wasn't retracting much because the metal diaphragm in the brake booster wasn't aligned properly with that large spring.

To add onto that, having air in the system, made the calipers lock up and not release thus the braking issue. Having replaced both items and having abs solenoids cycle a few times, that solved the issue as well since the abs pump was blocked for some reason. Power wasn't cycling the valves when I bled the system.

 

Air in the system wouldn't cause the brakes to lock up -- quite the opposite. Air is compressible, unlike fluids, so it can't transfer hydraulic force. An air bubble will make your brakes mushy at best, nonfunctional at worst.

 

Hmmm so that is pushing me towards master cylinder and brake booster.

Sent from my iPhone using Bimmerfest mobile app

 

I would suspect the master. A failed booster would not give you power assist, which would mean you'd have to really stand on the brakes to get any stopping power out of them. Turn your engine off while the car is still moving and try braking -- you'll get an idea what that feels like. Just make sure you don't do that with anything in your path that you could run into!

 

Exactly, with a failed booster, I literally had both my feet on the brake pedal trying so hard to stop the damn car...:yikes::yikes:

 

Well the stick n the pedal is back. Hard braking and sudden stops causes the pedal to hold just a little bit (not enough to stall the car) & booster seems to be working at half efficiency.more effort is required when braking. Abs still functions. No lights-on dash. im guessing a combination or improper maintenance of the brake system has cause booster and or master cylinder or both are failing. Im gonnna flush one last time with abs jumper trick se if maybe abs pump still has air. If not im part shopping lol

Sent from my iPhone using Bimmerfest

 

So the culprit has been narrowed down to vacuum leak when pressing the pedal in the booster. I was able to get a year out of it before it became almost impossible to drive

 

so do you need a booster? i have one for 45 plus shipping.


Andy

 

Yes I do location ?


Sent from my iPhone using Bimmerfest