Have your mechanic bleed all 4 brakes and adjust the rears.
Report back.

Could be fade from super-heated brakes.
Could be air in the system.
Could be failing components.

dylan

________________________________
From: Sheilah Rogers <sheilah@SHEILAH.ORG>
To: vanagon@GERRY.VANAGON.COM
Sent: Tue, August 17, 2010 3:04:44 PM
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.