E28 535i brake warning

["Dan, Marilyn, Anathea & Phillip Patzer" <bmrfamly@xxxxxxxxxx>]

Peter
  If I remember correctly, the E28 535i has a hydraulic accumulator
("bomb") for the brake power boost system.  Sorta like a basement storage
tank for a home with its own well.
  The power steering pump provides the pressurized fluid (ATF, or special
power steering fluid),  but pumps it too slowly to be of help in an
emergency, so high pressure fluid is stored in this nitrogen pressurized
"bomb".
  The fluid is directed into/out of the bomb via a pressure regulator which
has two warning light switches attached.  One is for inadequate incoming
pressure indicating a slipping or broken power steering belt, failed pump
or hoses.
  The second switch is to measure the outgoing fluid released upon brake
application.  Not too many notice this warning, as seldom do we look at the
dash during emergency braking.
  Other warning lights i.e. pad thickness can "flash" upon application of
brakes as symptoms first appear.
  A safe place to test these systems is in the driveway, in neutral, at idle.
  Jab the brake pedal to confirm which warning light, and the occasion of
the warning.
  Replace the "bomb" at first warning.  Carefully inspect inside the
connection port of the regulator prior to install of the new accumulator,
as sometimes valving mechanisms fall out of the regulator as the old bomb
is removed.  Using failed regulators can lead to failure of new
accumulators, power steering units and pumps.
  I can send jpeg's of failed and normal regulators upon request.

 Dan Patzer the CyberWrench from BIMMERS ONLY
72' tii touring   K1200LT   85' 732i   R850R
http://www.nwlink.com/~bmrfamly/   425-259-3601
 O.E.M. parts, Independant service since 1967
 12724  Marine Drive,  Marysville, Wa. 98271

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