[T3] BrakeBleeding

Dave Hall dave at hallvw.clara.co.uk
Fri Apr 22 05:07:29 PDT 2016


So fronts bleed OK now, but the rear wheel cylinders don't bleed well, and
you've checked the adjustment is OK.  Try removing the bleed valves one at a
time and check they are clear.  While doing that, you should get drips
coming out steadily if the rear hoses and pipes are clear.  That's a simpler
job than changing anything else, and will only cost you time.  

I hesitate to suggest undoing the union at the wheel cylinders, as they are
sometimes rusted to the pipes and you risk twisting off the pipe, but if the
valves are clear, and bleeding is still just drips not a squirt, work back
towards the MC looking for a blockage.  

If the long pipe is leaking, the pedal will go to the floor if you keep your
foot on it, and fluid should be evident. I understand that LHD cars can
suffer from corrosion - it's not a problem on RHD as the pipe routing
doesn't go near where your wet, salty shoes rest.  
Sometimes the MC leaks from the rear and the fluid goes into the tunnel,
appearing at the tunnel drain at the back.  If that's the case, the
reservoir level will drop in the compartment serving the rear circuit. It
can happen if the rear MC seal hardens - I had that happen once on my '71. 

Lifting the rear and leaving it a while might tempt air bubbles to collect
at the back, but as Jim says, there should be no reason for air to be drawn
in.

Dave
UK VW Type 3&4 Club
===================

-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of J. Jonik
Sent: 22 April 2016 06:04
To: type3 at vwtype3.org
Subject: Re: [T3] BrakeBleeding

Update:-  Frozen upper valve on two-valve caliper loosened (gentle breaker
bar on 7 mm wrench...wheel off to get access), plus a day of Liquid Wrench.
  Bleeding got a nice stream of fluid...but not a flutter of air.
So, we have both front calipers producing no air, just good stream of fluid
when bleeding.
-  Still...pedal needs a couple of little pumps to get good braking.  It
seems better, but not where it should be. Why?

- So far overlooked is...is the long metal brake line under carpet on floor
of driver's side leaking?...without wetness under car?
-  If I replace both rear Flex Hoses (a bear of a job) and the pedal still
doesn't perform properly, then what?  


Message: 1
Date: Sun, 17 Apr 2016 13:44:07 -0700
From: "William J" <catnine09 at dslextreme.com>
To: <type3 at vwtype3.org>
Subject: Re: [T3] Brake Bleeding
Message-ID: <6D981A8114DD4242B10BA41C31819BC5 at acere355056e8b>
Content-Type: text/plain; format=flowed; charset="utf-8";
    reply-type=original

 It's difficult to say since there is no info on what clogged the LF rubber
line in the first place.

 If the LF has a good stream of fluid out the bleeder then it seemes like
the MC works at least on the front .

 I would pull out the bleeder's and see if they are clogged first since they
are the smallest passage that can clog and it not there work back from the
RF hose by cracking the line and see if fluid comes out , may need to remove
the line to really know then there are the steel lines to the front  hoses
it may be easier to crack one loose where it fits to the RF rubber line.

 If rust comes out you may need to replace all the steel and rubber lines
and hope the calipers and wheel cylinders are not rusty inside . Yet I have
no idea what clogged the LF requiring replacement of the LF rubber line.

William
----- Original Message -----
From: "J. Jonik" <j_jonik at yahoo.com>
To: <type3 at vwtype3.org>
Sent: Sunday, April 17, 2016 1:12 PM
Subject: [T3] Brake Bleeding


> 71 Sqbk: Brakes got to need several foot pumps to work best.Jjust to make 
> sure things were tidy, I made sure rear brake pads were good thickness, 
> and adjusted. Put a bit more brake fluid in the reservoir, and began a 
> bleed job with a friend on the pedal.
> Right rear valve produced just a tiny spurt of air, then just drips 
> despite brake pedal being pushed down hard. Left rear....just drips, also 
> with no squirt. Front right, same thing.
> Front left, however, squirted like it's supposed to.
> So....is this hard evidence of Master Cylinder trouble? It can't be, can 
> it, that three out of four of the rubber brake lines going to the wheels 
> all clogged up around the same time.About a year (?) ago I had to replace 
> one of the front brake lines that was clogged solid. That was probably the

> one that worked well today. Are the others just catching up?
> Then, IF it's the Master Cylinder...I have over half a dozen of them in my

> brake box. All came from cars where they worked at the time the parts were

> taken. Is it likely that they won't work after being dry and idle for 
> years?
> What's the recommended plan of attack on this job?
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Message: 2
Date: Sun, 17 Apr 2016 23:29:27 +0100
From: "Dave Hall" <dave at hallvw.clara.co.uk>
To: <type3 at vwtype3.org>
Subject: Re: [T3] Brake Bleeding
Message-ID: <B243849BF4CD4B94AA60BBE984A998B4 at DavidPC>
Content-Type: text/plain;    charset="iso-8859-1"

The insides of the rubber hoses swell with age, and the layers can separate
and act like valves, stopping the free flow of fluid. What should be about a
1/8" hole is often down to maybe 1/16" or less.  I couldn't even blow
through an original front hose when I looked for what was stopping the
caliper working on my Fastback about 10 years ago.

The rears are less problematic, as they flex less, but eventually they will
close up too.  Jim has the correct rears - you won't find the right length
for the RH rear 'off the shelf' though the ones for the Type 2 Bus with CV
joints are close enough to use as an alternative if you can't hold on for
Jim.

Dave
UK VW Type 3&4 Club
===================  

-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of J. Jonik
Sent: 17 April 2016 21:13
To: type3 at vwtype3.org
Subject: [T3] Brake Bleeding

71 Sqbk:?? Brakes got to need several foot pumps to work best.Jjust to make
sure things were tidy, I made sure rear brake pads were good thickness, and
adjusted.? Put a bit more brake fluid in the reservoir, and began a bleed
job with a friend on the pedal.
Right rear valve produced just a tiny spurt of air, then just drips despite
brake pedal being pushed down hard. Left rear....just drips, also with no
squirt.?? Front right, same thing. 
? Front left, however, squirted like it's supposed to.
So....is this hard evidence of Master Cylinder trouble?? ?? It can't be, can
it, that three out of four of the rubber brake lines going to the wheels all
clogged up around the same time.About a year (?) ago I had to replace one of
the front brake lines that was clogged solid.? That was probably the one
that worked well today.? Are the others just catching up?
Then, IF it's the Master Cylinder...I have over half a dozen of them in my
brake box.? All came from cars where they worked at the time the parts were
taken.?? Is it likely that they won't work after being dry and idle for
years?
What's the recommended plan of attack on this job?
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Message: 3
Date: Sun, 17 Apr 2016 17:57:16 -0500
From: "Jim Adney" <jadney at VWType3.org>
To: type3 at vwtype3.org
Subject: Re: [T3] Brake Bleeding
Message-ID: <571414CC.5859.1E5E7B9 at jadney.VWType3.org>
Content-Type: text/plain; charset=ISO-8859-1

On 17 Apr 2016 at 20:12, J. Jonik wrote:

> 71 Sqbk:?? Brakes got to need several foot pumps to work best.Jjust to
> make sure things were tidy, I made sure rear brake pads were good
> thickness, and adjusted.? Put a bit more brake fluid in the reservoir,
> and began a bleed job with a friend on the pedal. Right rear valve
> produced just a tiny spurt of air, then just drips despite brake pedal
> being pushed down hard. Left rear....just drips, also with no
> squirt.?? Front right, same thing. ? Front left, however, squirted
> like it's supposed to.

Make sure the reservoir is not actually empty on one (the rear) side.

Make SURE all 4 rear shoes are adjusted. If even ONE of them doesn't 
come up hard against the drum, there is no way for pressure to build 
in the rear circuit.  

It's probably bad hoses, but check to make sure the bleed valves are 
not plugged themselves. Take them all the way out and see if this 
helps. Wiggle a small wire down the hole to make sure there's nothing 
inside blocking anything.

If that doesn't fix it, loosen a connection upstream of the hose and 
see if fluid squirts out there. If so, the hose is the problem. It's 
common for the front hoses to fail. Rear hoses fail less often, but 
it happens.

I carry ALL the brake hoses for Type 3s, including the correct IRS 
right rear that no one else has.  

> So....is this hard evidence of Master Cylinder trouble?? ?? It can't
> be, can it, that three out of four of the rubber brake lines going to
> the wheels all clogged up around the same time.About a year (?) ago I
> had to replace one of the front brake lines that was clogged solid.?
> That was probably the one that worked well today.? Are the others just
> catching up? 

This is probably not an MC problem, since you KNOW that the front 
circuit, at the very least, is working correctly.

> Then, IF it's the Master Cylinder...I have over half a dozen of them
> in my brake box.? All came from cars where they worked at the time the
> parts were taken.?? Is it likely that they won't work after being dry
> and idle for years? 

There is 0% chance that an MC stored for a few years with brake fluid 
in it, will be an improvement. There is ~30% chance that such an MC 
is rebuildable. Stored like that, the bores will all be rusty.

Standard DoT 3 or 4 brake fluid absorbs moisture out of the air, even 
just sitting in the car. That's why you should always buy a new can 
of brake fluid when you add fluid. Fluid from an open can will 
already be moisture laden. Moist fluid boils at a lower temp and 
tends to promote corrosion of the metal parts that are exposed to it, 
like your MC and wheel cylinder bores. I recommend DoT-5 Silicone 
brake fluid, because it does not have this problem.  

If you don't want to bother with DoT-5, you should flush fresh fluid 
thru your system every few years. Pump and flush until you see new, 
clean fluid come out of all 4 wheels.

-- 
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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