1991 Ford E-350 Ambulance Brake Pedal Fade

1991 FORD E-SERIES VAN
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MCQUEEN REPAIR
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Replaced Master Cyl with NEW unit (I Avoid Reman Units as much as possible), Bled System, checked adjustment, Still had Pedal fade, Replaced Master With second New Unit.

With Engine running, pedal still slowly fades to floor. RABS light is on but no codes are stored.

30+ Years in the Biz, and I'm Stumped! :?
Nov 12, 2007 at 11:39 PM
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FAIRRACING31
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Good possibilty you have a frozen or sticking front calipar.
Nov 13, 2007 at 12:11 AM
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MCQUEEN REPAIR
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Calipers and Wheel Cylinders were first on inspection list, Calipers Collapsed easily, no leaks, slides are ok, wheel cyls. and rear shoes appear to have been replaced within last 6 mos.
Nov 13, 2007 at 12:23 AM
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MCQUEEN REPAIR
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Replaced Vacuum Booster, Now have proper Pedal Height, and NO FADE! :mrgreen: :mrgreen: :mrgreen:
Nov 13, 2007 at 10:50 AM
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FAIRRACING31
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Wow!, that is a new one on me. Never seen a brake booster cause pedal fade. How did you determine it was the brake booster?
Nov 13, 2007 at 11:09 AM
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MCQUEEN REPAIR
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I isolated the Master Cylinder (Installed plugs in line Fittings), Engine off, Vehicle had a solid pedal. When I started the engine, the pedal faded away. on the second test I stepped on the brake with the engine running. When the pedal reached the halfway point, I shut the engine off. The pedal stopped dropping. after 1 1/2 minutes of applying pressure, and no pedal fade, I concluded the booster must be bad.

Fortunately, I was right. I've been repairing cars for 30+ years and have never seen a booster fail in this way - a good Tech is always learning!
Nov 13, 2007 at 8:04 PM
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