More Brake Problems

[Alan cordeiro <cordeiro@avlna.com>]

    The car: 1990 200T.  63K miles.


    At this point, I took the car 90 miles to the nearest dealer, who 
    tested the system and said that 1)  the brake servo was OK (I read 
    the test instuctions wrong) and 2)  the system was putting out 1800 
    PSI, which indicates that the hydraulic pump is generating pressure 
    OK. 

    But the damn brake light NOW stays on 'most all the time!!!  Oh, it 
    might go out for a few minutes, but it's at random times as far as I 
    can discern...there's no pattern.

    So - I *WAS* ready to be convinced the only problem was a faulty 
    pressure warning light, because there was no other problem appearing.  
    The switch screws into the brake servo and is easy to replace.

    But TODAY, my wife said the brakes felt spongy twice when she started 
    it after it had been sitting for 3+ hours.

    I would SURE welcome opinions and suggestions on how to diagnose and 

    Al Powell                           Voice:  409/845-2807
    Ag Communications                   Fax:    409/862-1202

Al,

If I remember correctly, the pump should be putting put 150 bar,
more like 2200 psi.

I seems like the pump occasionally puts out LESS than even 1800
every now and then, may just be a bad relief valve ( the one
that decides when it has hit 2200 psi, and dumps the extra
pressure. This valve sits right in the middle of the rear
section of the ZF pump, you had better really know what you're
doing if you want to start opening the two halves of the pump...
lots of "O-rings", LOTS OF POTENTIAL LEAK POINTS...


But " spongy " ??, typically loss of assist makes the brakes
feel real HARD.


Alan Cordeiro