My bet is that the rear brakes are not adjusted right or a cable is bad and
the brakes were dragging. This would heat them up and really expand the
drums and/or vaporize the fluid in the rear cylinders.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Sheilah Rogers
Sent: Tuesday, August 17, 2010 3:05 PM
To: vanagon@GERRY.VANAGON.COM
Subject: brake question

Howdy Folks,

I'm wondering if I can bother the list's hive mind for some answers (that I
already could not find via the search tool)?

Basically something went weird with my brakes and my mechanic cannot
reproduce the problem.

So I was driving in ~80F weather, up and down a not so steep road but some
curves, about 30 minutes of said road was unpaved, van warmed up of course.
Brakes no problem. (not sure if weather matters but there it is.) I drove
about 45minutes total here.

Then I got on the highway for another 45 minutes-ish. When I went to slow
down a bit, it was like my brake peddle wasn't responding with its normal
sort of push-back and instead, the brake pedal just dropped with no brake
functionality about 80% to the floor before it engaged. Once engaged, I
could slow the van down but of course I then had the pedal to the medal just
to slow down a bit.

Being on a quiet highway I kept going, figured I'd pull over in a bigger
town and at least I can stop the van. But after 30minutes, the brake resumed
normal so I just continued driving to my mechanic's.

The next day he could not reproduce the problem, after warming up the van,
driving on hills, 30minutes or so. He says 50% chance it's the master
cylinder. But he's not sure (???) what else it would be since the brake
fluid seems fine.

Anything else that should be ruled out or should I just have the master
cylinder replaced and hope it doesn't give out (50% chance?!) the next time
I'm driving on presumably worse mountain roads. I don't feel safe or
comfortable with this plan.

Does anyone want to weigh in at all?
Mucho thanks appreciated.

Sheilah

1986 Westy water-cooled vanagon: Vanna White.