In my perm files (archive)

I saw on the B_C_G FAQ that someone had done that as well. Is there a site that you know of that
gives details of the fix. There wasn't one on the B_C_G page. I'd really appreciate anything you
could direct me towards!

Thanks
--Kane--

I copied the following from the B.C.G. I don't know if you found this or not.

Brake Boost/Master Cylinder Leak

Had the same problem with the hydraulic leak from the brake booster on my '87 635. The leak is
from a failed "O" ring inside the booster. The ring is about 2" in diameter and goes around the
plastic plug in the front of the booster. The screw you feel under the booster is the retaining screw
for the plug which, by the way, has a fairly strong spring behind it. Be careful if you take it apart. I
took the booster out myself and got a replacement "O" ring from Steve Haygood, the guy who runs
the 6 Series Register.

Addendum:

This O-ring is a 3mmX38mm (ID) and can be found at Pep Boys. Don Meis and I have both found
them there.

If you have a Bentley manual then follow the directions for removing the master cylinder then the
brake booster. Remove the retaining screw from under the brake booster (be careful as there is a
large spring inside). Replace the o-ring 3mmx38mm (inside diameter) and reinstall everything. You
will have to then bleed the brake system. It is pretty straightfoward, but takes several hours to
complete. It fixed my leak completely and now my driveway looks better plus it saved me a couple
hundred dollars! Good luck.

Greg T

http://normgrills.net/bcg/

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