The booster is not causing the pedal to sink to the floor. You have a
hydraulic problem. If there are no external leaks, then the master is
leaking internally either past the piston or one of the check valves.
The hissing is normal under these conditions.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Cary Chiang
Sent: Wednesday, August 17, 2005 8:22 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Brake Vacuum Booster Replacement Questions

Hello Listees:
I can hear a vacuum hiss from under the instrument panel when I
push on the brake pedal of my '90 Vanagon.  The brake pedal slowly
goes to the floor.  I checked the vacuum hose fitting to the right
of the brake master cylinder that connects to the brake booster,
but it doesn't seem to be leaking.  I can only guess that the brake
booster itself is leaking internally.
Questions:
Are there any other external connections or other potential leakage
spots?

Can the brake booster be removed & replaced without removing the
dash?  It looks like the instrument panel, brake master cylinder,
and two dash support struts need to be removed to get at the
booster, but can the dash be left in place?

I'm having trouble receiving e-mail right now (messages to me will
bounce), but I can read replies on the Vanagon.com archives.
Thanks in advance for your replies!

Cary