Date: Sun, 29 May 2011 12:54:11 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Brakes problems
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=response
sure sounds like a 'new' bad used master cylinder.
the poor things seldom get serviced anyway - like lots of old vans have
'black water' in the brake system that once was nice brake fluid. ( as you
know...bf absorbs moisture from the air ..
even just sitting ........eventually it turns to 'just very black water'
..........and water leads to corrosion. )
AND..........I'll bet you right here and now ..
tell me you *didn't* do this .. !
you stroked the pedal all the way to the floor in your manual bleeding
process.
In case you did .........
One should never stoke the brake pedal all the way to the floor in bleeding
unless it's a brand new cylinder.
Because ......on an old one, or a used in-service one...since the piston
never slides down to the bottom in normal use....there's a section of the
cylinder that gets rough .......from corrosion ..and from the seals not
sliding over that section, since the brake pedal should never go to the
floor anyway.
As soon as you stoke the pedal to the floor on a used MC ...you make the
seals slide over that untouched area, and that isn't good for the piston
seals.
I have lots of used brake master cylinders.
If one works properly after being put on a van ..I consider that just good
luck.
And never ever stoke a used brake master cylinder all the way to the floor
with a manual brake bleeding process.
( which I prefer btw, since there's 'feel' involved in the process, and you
can feel that it's actually producing pressure. With a pressure bleeder you
don't get that advantage. )
Scott
www.turbovans.com
----- Original Message -----
From: "John Jensen" <bluesbug@VERIZON.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, May 29, 2011 12:07 PM
Subject: Brakes problems
>I don't know how to diagnose my brake problem. I changed master
> cylinders and bled the brakes already. Anyway the basic symptom is if I
> pump them up and push hard the brakes hold pressure. If I ease off on
> the pressure the slowly go to the floor. Sometimes if I quickly push
> the brake pedal it goes to the floor, but a quick pump will make it hold
> the pressure. There are more symptoms but that seems to be the main
> one. I don't see any evidence of leaking around the wheel cylinders.
> Now fact is I substituted an old master cylinder I had lying around from
> parting out van a few years ago. The symptoms from the replacement MC
> are more or less the same as with the one I replaced, except the one I
> replaced wouldn't hold pressure at all.
> Any clues or tutorials from the wise members of this group?
>
> 1980 Aircooled Westfalia
>
> John Jensen
> johnjensen@johnjensenartist.com
> http://www.johnjensenartist.com
> bluesbug@verizon.net
