I am with Dave on the Bosch brake parts comment. They may make ABS (I
don't know) but I do see ATE, Girling and other vendors.

Does this hissing happen when the cap is off the master cylinder?

On my Toyota there was a specification for brake pushrod length. There
is a similar meashurement in my 1980-1984 VW manual. Did you check
this setting as per your repair manual?

How do you bleed your brakes? I have done the two person: down, hold,
open bleed screw, close bleed screw, up. Repeat. It works better than
one person. I recently used the Motion power brake bleeder
http://www.germanautoparts.com/tools to flush air and old fluid out.
It works great and requires only one person. You can also check for
fluid restrictions as I mentioned before.

If you somehow managed to leave a plug in something before you
tightened a line you may have some component plugged.

On Thu, 26 Jul 2007 22:34:12 -0500, "dave AKA vwdoc1"
> wrote:

>Having fun yet? Don't stop now! <g>
>Try to measure the clearance between the brake booster rod and the master
>cylinder!
>Find out why it is hard to compress the caliper piston back in the cylinder!
>Loosen its line at the master and then compress to note any difference.
>
>TEST:
>Take it for the test drive until that RF caliper starts to lock up and then
>loosen the brake master cylinder to booster nuts so the cylinder can move
>away just a little. Hopefully this will free up the caliper.
>
>I did not know that BOSCH made master cylinders! ATE does and Girling and
>maybe some offbrand aftermarkets.
>Are you buying these parts from a Auto Parts store like Murrays or Advance
>Auto Parts which might mean that they are remanufactured?
>
>
>
>"lynn lascu" > wrote in message
...
>> Many thanks to all who have responded to my brake problem. I still have
>> the same thing going on after replacing the master twice, the calipers
>> twice, the rubber lines twice. he car has never hit potholes or such.
>> i've replaced the pro valve, just put on another brake check valve today
>> and still no luck. When I use a c-clamp to close the calper on the right
>> side I heard a hissing sound coming around the booster area, and the
>> caliper is very hard to close. The left side closes better when I
>> c-clamp it and no hissing. The right caliper seems to have alot of
>> pressure when I c-clamp it. This all started when I replaced the master
>> 2 months ago. One day the brakes just faded to the floor so I figured it
>> ws the master cylinder that went bad. Now I've replaced everything new
>> and problems. All parts purchased are Bosh parts with lifetime
>> warranties. Is a leak down test very expensive and can I do this myself?
>> lost and confused this is keeping me up because I can't solve my problem
>> and its really driving me nuts.
>>
>