[Vwdiesel] Air suckers?

[Val Christian]

I have had it happen, perhaps on an A1, perhaps on a Rambler American,
and on a 69 Ford E-300, that a well worn DRUM cylinder will somehow 
get air into it.  Now when that happens, I rebuild/replace the cylinders.
I can't say why or how it happens.  I can say that on one car, oh, 
a Chevy Celebrity Station Wagon, there was just a tiny bit of staining
where fluid had soaked up brake dust, implying a small weeping.

Now when I encounter what you're describing, I simply replace the 
cylinders in question.  Never seen it on caliper cylinders.

Val



> 
> I have had a strange phenomenon with the brakes on the A2.
> 
> It's been a years or so since I did them all over, incl drums, rotors, shoes
> and pads.
> Blew out all the old fluid by blowing in new stuff. 
> 
> They worked great all year, then started to get low. I thought it might be a
> stuck adjuster and pulled both drums and checked. Linings were good, and
> adjusters seemed to work ok, and when I put it all back together, they were
> still low.
> 
> So I decided to bleed the left rear, and sure enough, got air out of it.
> Tried the brakes, just like new. Drove for a month, they went soft again,
> bled both rear wheels tonight and got a little air from both. Brakes are
> fine now.
> 
> Where is it coming from??
> 
> The reservoir is full, has never lost any fluid, no puddles on the ground,
> pedal is firm and does not "creep".
> 
> Yet it's as if air got in to the system somehow, and only to the back brakes.
> 
> Is it possible air could work back past the rubber cups in the wheel cylinders. 
> 
> They are pretty old. perhaps there are pits that hold air when relaxed, and
> with application, the cups move out past them and air escapes into the cyl.
> 
> I doubt this, as the pressure of application is about 2500 LB sq in.
> 
> If it happens again, I will replace both cylinders.
> 
> Is it possible the "equalizer" valve might let air in under certain
> conditions? This one has been seized for years.
> 
> Sandy
> 
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