Bomb Gone Again?

[james accordino]

--- Christopher Ritchie <critchie1 at hotmail.com> wrote:
> The troubleshooting procedure in the Bentley for the
> 
> steering/brake/hydraulic pump is to measure its
> output with special Audi 
> test equipment.  How do you test the pump without
> this piece of special test 
> equipment?  How do you distinguish from a pump that
> is not putting out 
> enough pressure to a "bomb" that is unable to store
> sufficient pressure?
> 
IME the pumps don't fail to produce pressure, they
leak.  This does not mean that a pump CAN'T fail, just
that I don't think they do very often.  I've never
seen (15-20) a pump fail to produce sufficient
pressure.  The servo leak-down test is the easiest, so
I'd start there.  Just pull the hose off the resivour
and watch to see if fluid continues to drain.  As Phil
said, "contents of the hose are fine, any more and
there's a problem".  The pedal pump count is the best
test I've found so far.  I don't have the necessary
gauges either so:

Pump produces "normal" braking/steering function while
running.

Servo is not leaking down causing pressure to escape.

After shutoff, the bomb fails the pedal test.

This has been the scenario in both my cars and 2
others I've diagnosed/repaired.  Both other owners had
the pumps replaced and that did not cure the problem. 
None of the 6 servos I have personally checked have
leaked either.  All the bombs were original and at
least 11 yrs. old at the time of replacement.  One
other thing, 1 persons rack leaked into the boot SO
badly that it was causing the light to come on.  I
didn't check to see if it was because of pressure
bleed-down (I don't think that can happen as I
understand the system) or because of the low fluid
light. 

HTH
Jim Accordino