e34 m5 brake prob

[Unregistered]

Well, after yet another night working on the car, i've replaced my master cylinder, rebled the brakes with an entire bottle of super blue, and still, the pedal goes all the way to the floor. Something is very wrong here, and i can only assume it is in the ABS system. I've even done the "pump the pedal 30 times to get fluid into the ABS system," and still, no brakes! Anyone have any last ideas before it goes to the shop?

Thanks,
Andrew
1991 e34 ///M5

[TheGeak]

i dont' know if this helps at all, but have you been to this link

http://www.garageboy.com//bmw/bleeder.html

to make sure you're doing the bleeding properly?

[Javier]

http://caracas.intercable.net.ve/jga.../Bleeding.jpeg

It may complement information. Think you will need the presurized bleeder for doing the job.

[Jr ///M5]

Sounds like you didn't bench bleed the master cylinder. You will have to remove it, bench bleed it, re-install and then proceed to bleed the brake lines starting with the right rear, left rear, left front, and finally right front. Once you are through with this sequence, bleed the wheels one more time and you should be good to go.

Jr
'91 ///M5

[Bill R.]

that rules that out in my mind and usually if its a fault with the abs you still have conventional brakes and normal pedal.

Sounds like you didn't bench bleed the master cylinder. You will have to remove it, bench bleed it, re-install and then proceed to bleed the brake lines starting with the right rear, left rear, left front, and finally right front. Once you are through with this sequence, bleed the wheels one more time and you should be good to go.

Jr
'91 ///M5

[datsclark]

Well, another gallon of brake fluid, i'm still getting bits of air out from time to time. I've got it to the point where i can drive and get the ABS to come on, but i still can't get it all good, there must be a lot still in there somewhere.

I have indeed bench-bled the master cylinder, the brand new one, and i've rebled the brakes twice after some driving. But still, its bad.

So, this gets to this ABS "special tool" that i keep sorta hearing about, but i have never seen anything concrete out there.

Has anyone heard of this? I'd really like to fix this without going to the dealer, but it might the only way to get the air out of the ABS system.

-Andrew
1991 e34 ///M5

[Bellicose Right Winger]

Perhaps you've already done this but....
Have you bled every connection at the master cylinder until they're air free? There's no point in bleeding the calipers until the MC's air free.
Are you pumping the brake pedal with engine running to reduce pedal effort and generate higher line pressures by taking advantage of brake booster?
Make sure your helper is pumping brakes rapidly and following the pedal to the floor as you open the bleed screw/flare fitting. I've trained my wife to pump brake pedal as rapidly as possible 10 times and hold...she'll give me a "holding" response, I'll open the bleed screw/flare fitting and reply with "again" and we repeat the sequence. Sounds simple....maybe even silly but it's effective and works on slave cylinders too. BTW the actual pump count isn't important but it gives the helper an easily repeatable target.

Good luck
Paul Shovestul

[mike wong]

I've trained my wife to pump brake pedal as rapidly as possible 10 times and hold...she'll give me a "holding" response, I'll open the bleed screw/flare fitting and reply with "again" and we repeat the sequence.