On the Vanagon the low pedal before pumping is usually a sign of miss
adjusted or incorrectly installed rear brakes along with the wrong wheel
cylinders not having the springs to prevent the pistons from getting sucked
back. A firm pedal that sinks is a sign of leakage somewhere. Another source
of lousy pedal feel and brake performance is the rear brake pressure
regulator. These do go bad!

To really test the brake system you need a brake pressure gauge set. If
there are absolutely no external leaks the sinking pedal is most likely a
bad check in the master cylinder. Before ruling out leaks pull the rear
drums. You would be surprised how much brake fluid can be absorbed by the
rear shoes before a leak is obvious.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Craig Cowan
Sent: Friday, April 26, 2013 1:45 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Brake pedal goes to the floor

Hey gang.
Last summer I had a problem with my master cylinder in my syncro, or so I
thought. The pedal would "Sometimes" go all the way to the floor but could
pump up to build pressure. Other times it would work fine.
Anyway, I replaced the master cylinder, bled the system and all was well.

Well now about 1000 miles later, i've got the same symptoms occurring. The
fluid level has not gone down, so I don't have a leak. It feels as though
something has blown out and is allowing a piston somewhere in the system to
move freely. I'm thinking it's the master again, but it sure is weird to
kill two as quickly as I have.

Any thoughts?
When the pedal works, it's firm and functional. But sometimes I get a firm
pedal, and while keeping my foot on the pedal it slowly moves towards the
floor.

-Craig Cowan