I don't pay dealers to do jack $hit for me. I do it all. Compared to an engine out major service on a Ferrari or a Carrera, a brake booster is a walk in the park.

 

Brand new rebuilt unit is $140. Why buy used?

 

Closing this out.


The rebuilt booster came today, installed it and all is well. One hint for the next guy, at least on E60, install the master cylinder first on to the booster, then install the assembly into the car. You save a bundle of time.

 

thanks for the update.

 

Well, all is not well.


I drove it for 1 mile and ALL BRAKES locked up. Released the lines, rebled the brakes, make sure fill up fluild to Max level and no more. Drove it and immediately the brakes are dragging. Pull into the garage and they all locked up.


Is it possible that the master cylinder decided to go just now? Or, it is possible that the new rebuilt booster is somehow causing the brakes to bind and lock up?

 

Did you touch the "push-rod" of the brake pedal that pushes on the MC? Because of production variations, and especially with aftermarket parts, the booster might not be the exact same size so the pushrod will need to be adjusted so there's 1-3 mm of brake pedal play. By the sounds of it, it's probably pushing the MC slightly causing the brakes to be applied. The pushrod will probably have to be shortened.

This is the procedure for a Honda, but I think for a BMW it should be similar. I replaced the MC on my acura 2 years ago and luckily I didn't have to adjust the pushrod.
http://my.cardone.com/techdocs/PT%2053-0001.pdf

 

I did not touch the push rod, but from the dragging brakes, I surmised that there is an adjustment procedure that is not shown in the Bentley manual. I am going to look for a bmw one somewhere.

 

could you try maybe loosening the master cylinder bolts so that the cylinder moves away from booster a bit. and see if that fixes issue?
is the pedal returning all the way up?

 

I could, but don't I lose the vacuum seal that way?

 

dont drive with the master cylinder loose, but just loosen it to see if it gets rid of the stuck brakes. the booster pushes on the master cylinder rod. that may help you determine if the rod is getting stuck.
but first i'd check to make sure pedal comes all the way up first.