brakes No Brake/clutch Pedal - Brake Booster And/or Mastery Cyl. Failing?

[zdealey]

Finally, I submit and and it's time to ask the pros.  Over the last 3 weekends, I've unsuccessfully tired to bleed my hydraulic system.  A friend loaned me a pressure bleeder and I was sure that it would do the trick.  Yesterday, we went through 1.5 bottles of brake fluid, bled all four corners in the correct order, but my pedals are still not stiffening up and the brakes are not working (front or rear).

 

Then, we noticed a "shrrr, shrrr" sound coming from the brake booster with each pump of the brake pedal (like a bicycle pump).  I can also feel air exiting the the back of the brake booster.  Pretty much everything has been replaced in terms of the brake/clutch/hydraulic system EXCEPT the brake master cylinder and of course the brake booster has never been refreshed.

 

Before I drop $400 bucks on those items, could the brake booster be the root cause of my woes here?  Could it be a combination of the the master cylinder and the booster failing?  Feedback is highly welcomed and appreciated.

[PaulTWinterton]

Most likely the MC is leaking/passing fluid to the inside of the booster.  A new MC is not too expensive and a worthwhile replacement for safety reasons. 

 

You may be able to drain and clean out the booster without problem.  More advice may be needed here.

[Stevenc22]

Loosen the 2 nuts holding the MC to the booster and peer into the gap and see if you can see fluid in the booster!

[zdealey]

Thank you Paul and Steve for the feedback.  i"m going to replace the MC for sure and will investigate the booster as well.  I'm assuming the air that I'm feeling pump out of the back of the booster upon brake depressing the brake pedal is not good.  Maybe a the booster refresh is advisable here too.  After all, I've replaced EVERYTHING on this car so far.  Why stop now lol 

[Stevenc22]

I just replaced my MC and Booster 2 months ago. Pretty painful job especially if the metal brake lines decide to fuse to the MC. Make sure you use flare nut wrenches and good luck.

Edited June 9, 2014 by Stevenc22

[zdealey]

I just replaced my MC and Booster 2 months ago. Pretty painful job especially if the metal brake lines decide to fuse to the MC. Make sure you use flare nut wrenches and good luck.

Did you go with the Ireland Engineering rebuild for the booster?  I've been through the pain of working with the 40+ year old rigid brake lines, so I'll be good there.  I've gotta think the booster and/or MC are my problem.

[Stevenc22]

I bought a centric rebuilt booster.Centric has a mixed reputation but i ended up with a very nice rebuild.

 

http://www.partsgeek.com/catalog/1976/bmw/2002/brake/brake_booster.html

[PaulTWinterton]

My booster had some fluid in it, but it was fine.

Fluid eats through everything, but if the seepage was NOT happening for too long your booster may be ok. If there is rust inside the booster, I would replace it. More experience here, please. I'm not an expert on boosters. Others may have better advice.

[zdealey]

Thanks guys and I'll certainly check the booster for fluid.  I might as well replace both items since I've taken the car this far:

 

http://www.bmw2002faq.com/blog/47/entry-116-its-finally-coming-together/

[Mark92131]

I went through this exercise as well after updating my brakes to Volvo Girling Calipers and 320i hubs and rotors.  I replaced the master cylinder after going through 2 quarts of brake fluid trying to get a firm pedal.  It turned out that I had the calipers installed wrong so one the bleed screws was oriented in a position that kept it from completely clearing all the air.  Once the calipers were installed in their correct positions, the brakes bled properly and the pedal firmed up.

 

Just something else to check...

 

Mark92131