Here's the deal, my Dak's brakes have gone away. These are the symptoms.
1. When you try to stop, the pedal goes to the floor with very little
braking taking place.
2. While driving you can not pump it up, every stroke goes to the floor.
3. With the engine off, the brake goes to the floor on the first stroke,
every stroke after
that is firm and a reasonable distance from the floor.
3. Hold the brake pedal and start the engine, it drops to the floor as soon
as the engine
starts.
4. Pumping the brakes with the engine off facilitates bleeding the
calipers, every thing
seemed normal while bleeding the brakes.
5. Vacuum at the booster looks good.
6. The valve on the booster is working.
7. If you pull the booster valve, with the engine off, before you hit the
brakes and
use up the vacuum, it hisses as air gets sucked in.
What I have done so far, I was postponing a brake overhaul anyway so I
started there.
1. New Pads, rotors, bearings, seals and hardware up front, followed by
bleeding of the calipers.
2. New drums, pads and hardware in the rear followed by ballpark adjustment of
the shoes and parking brake (I ran out of time).
3. New master cylinder, bench bled and installed before other bleeding took
place.
This problem seemed to happen over night, no fluid loss or sign of leaking.
All the above
changes have not affected the problem in any way.
My feeling is a bad booster, but I can not find anything to back this up or
explain how a
booster could make my brakes work worse when the engine is running than
when the
engine is stopped, in fact the first pump after shutdown is bad because
there is still
vacuum in the booster.
Thanks in advance.
Mark Johnson, member MML, RAMM and APA
1970 Sassy Grass Green, AAR 'Cuda
1973 Challenger, 318/904 soon to be 360/727
1940 Chrysler Royal Coupe, 440/727
1992 Dakota, LE,V6/auto/OD
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