I have a 95 Chevy S-10 Blazer with 4WD. When I initially come to a
stop the pedal is nice and firm but after I'm stopped in traffic, the
brake pedal will slowly sink to the floor. I checked for external
leaks and found none. The master cylinder has been replaced 4 times,
the last time with a new (not reman) unit. The BPMV for the anti-lock
system has also been replaced. But the problem remains. Are
combination valves known to leak internally? Is there air in the
system or BPMV? Can the BPMV be bleed without a scan tool? Bleeding
the system manually does not show air and does not correct the
problem. Any other ideas? Thanks in advance!
Lower vac. when driving down the road do to higher rpms. This means less
help at the booster the first time he applies the brakes. Then when he
stops the engine rpms drop and produces a higher vac. That is why the
pedal drops a bit, the higher vacuum makes the booster work better.
Problem could be a small vac.leak or the check valve may be starting to
"Gary Glaenzer" < email@example.com> wrote in message
What do you think happens the instant that you move your
foot from the gas pedal to the brake pedal? And what the
hell is the purpose of the check valve in the vacuum line
to the booster?
You might be right, but I've never seen it.
Never owned a Jeep that had a bad check valve or vac. reservoir have
you. My 88 did exactly this with a small leak in the res.When sitting
still the vac would get higher and the pedal would drop. Took me three
weeks to find it since I had gone through the brakes twice.
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