'87 5kCSTQ - Wierd brake problem

[audidude@sprynet.com]

Yesterday, while stuck in traffic on the way to work, my brake warning light 
came on, and when traffic started moving again, I soon discovered that all the 
brake boost was gone.  Steering was normal and (I discovered later) so was the 
hydraulic fluid level. Same situation when I drove home from work: no brake 
boost but steering was normal. A mile or so before I reached home (about a 
20-minute trip), the brake boost suddenly returned!  Today the same thing 
happened, although the boost went away and came back within minutes.  What could 
be causing this weirdness?  The steering rack and the brakes run off the same 
system.  Why does one go out but the other is unaffected?

The hydraulic pressure accumulator (bomb) is new, replaced less than a month 
ago.  The pump, a rebuilt unit that was on the car when I bought it about three 
years ago, is starting to ooze slightly, but doesn't really lose any noticeable 
amount of fluid.  The fluid level in the reservoir is within the normal range, 
and I don't seem to be losing any.  It's got me stumped, but maybe someone else 
has had the same experience.

John Winkelman
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