RE: Brake pressure problem '86 5KTQ (pump & bomb?)

[Kneale Brownson <knotnook@traverse.com>]

I knew the steering/brake functions were separated within the pump, but I
didn't think to view them as two pumps on one shaft, which, of course, is
the actual case.  If I stab the brakes on the '91, I get a brief flash of
the small, square red brake light.   Is this compatible with the nearly
immediate hard pedal when pumping after the engine is shut off (ie:  bomb
failure)?

In my '87 5ktq, I got the larger red triangle and beeper warning before
replacing the "bomb".  Those warnings disappeared with the replacement.   I
also resealed the pump(s), but that was several weeks later and it was
because it was leaking.   Then I replaced the master cylinder because of
the rear brakes hanging up. 

Thanks, once more, Kneale Brownson


At 05:27 PM 11/17/99 -0800, Buchholz, Steven wrote:
>> My '86 5ktq parts car has just one pump pressurizing the 
>> hydraulic brake
>> booster and the steering rack, just like my '87 5ktq driver 
>> and my "new"
>> '91 200tq20v.  The latter shows no brake warning sign in the 
>> instrument
>> panel square where my '87 showed the red triangle when that 
>> car's "bomb"
>> was bad, but the '91 "fails" the 30-pumps-to-hard-pedal test 
>> after engine
>> shut-off.  Is there a different "bad bomb" dashboard warning 
>> on the '91?
>
>You may have what appears to be a single pump hooked up to the drive belt,
>but there are in fact two individual pumps in that mechanical package ... as
>you can tell by the fact that there are separate high pressure lines from
>the pump to the steering rack and the brake pressure accumulator.  The older
>cars like my ur-q have a single pump and the bomb has a pressure regulator
>valve scheme to supply pressure to the brakes and steering.  
>
>What you would notice as a bad bomb indication for any of the cars you
>mention is the brake warning in a situation where you press quickly and hard
>on the brakes, like in a panic stop.  The pump cannot supply enough fluid
>quickly enough to support this sort of thing, and that is why the light
>comes on.  If your only problem was the bomb you would not see the brake
>warning at any other time.  
>
>HTH!
>Steve Buchholz
>San Jose, CA (USA)