[V8] Hydraulic system problem

[NicolCS at aol.com]

It sounds to me like the system's pressure regulator isn't bypassing  excess 
pressure back to the reservoir - instead the pump is stalling against  
unregulated high-pressure. I don't know enough about these systems to know  where the 
regulation takes place, but I know enough about hydraulics to know  that 
there has to be one somewhere.  Don't forget that there are two  outputs from the 
pump, one for the brakes (and the bomb) and another for  the PS (Someone 
correct me if I'm wrong, I haven't worked on my hydraulics  for several years and 
my knowledge relates to a non-Servotronic  '90).  If your car has dual outputs 
like mine does, either system  could be the problem and they would both have 
independent pressure  regulation.  The master cylinder booster *may* provide 
this function  for the brake system. Mine occasionally bypasses all brake boost 
pressure and a  hard application of the brakes restores the boost pressure.  
This leads me  to believe that the master cylinder booster section contains the 
pressure  regulation feature, but this is speculation.  When I was trouble 
shooting  my system, I installed a pressure gauge (3000 psi) in place of the 
pressure  warning switch that's under the MC booster.
Hope this helps,
Craig Nicol
90 V8Q, 95.5 S6 Avant
 
 
 Well this weekend Ron And I decided to tackle the timing belt and  power 
steering pump leak On my 92 v8q. Belt went on and off without a problem  (helps 
when you have the proper tools ;) ) the pump on the other hand, was a  
different story. Replaced it with a known good one and the the pump wouldn't  spin 
when the engine was running. WTF I'm thinking. So I take it back off, and  it 
spins just fine. Prime it with some fluid and turn it by hand to make sure it  
actually pumps. I does, so I put it back on. Still wont turn with the motor. So  
I get the bright idea that maybe there is a blockage somewhere that's keeping 
 the pump from turning. So, with the motor running, I crack open the high  
pressure line slowly, and the pump starts turning. tighten up the line, and it  
seizes up again. So now I think I found the problem, but just for giggles, I 
try  the line going to the bomb from the pump. Crack that line open with the 
motor  running, and the pump starts to turn. Tighten it up, and the pu
mp freezes  again. I have also tried the old pump that was weeping from one 
of the plugs,  and I have the same problem. I've been told that it could be the 
rack or the  bomb (duh..I'm thinking to my self, that the only two things in 
the system left)  The bomb holds pressure with car off no problem. I have 
suspected bad  servotronic , and disconnected it, but still have same issue Can 
anyone help  with Ideas or BTDT? Thanks AL


 



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