Coupe GT brakes.

[Lyle Pratt <lhpratt@ixi.net>]

Listmembers:

I own a 1987 Audi Coupe GT with the late NG engine.  While driving the
Continental Divide yesterday I suddenly heard a 'hissing' sound coming
from beneath the dash.  The hissing sounds like either air escaping or
being sucked in through a small hole.  This sound stops immediately when
the brake pedal is depressed, but returns the instant I lift off the
brake.  Today I disassembled the lower dash to reveal where the brake
booster push rod goes through the firewall, and started the engine
again.  The sound is apparently coming from this seal where the rod
leaves the passenger compartment.  The sound in almost inaudible from
the engine compartment.

Questions:  Which parts do I need to replace?  Do I need to replace the
booster, master cylinder, and regulator, or just the seals on either
side of the brake booster mount?

I have priced the following items, and was wondering if these prices
sound reasonable.  Master Cyl. $149, Brake Booster $199, Regulater $90.
All from Blaufergnugen.

Any assistance in diagnosis or repair procedure would be greatly
appreciated as I am hoping to head up to Glacier Park in Montana early
next week.  Much thanks in advance.  ALP.