Baffling brake problem

189,000 MILES • 2.2L • 4 CYL • RWD • AUTOMATIC
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YOSHI1656
  • MEMBER
  • 1 POST
I've replaced everything but the brake booster and the proportioning valve on my truck. The brakes bleed while the engine is off. When I start the truck the brakes have no pressure and the peddle will drop straight to the floor. I'm in the process of replacing the booster, but have been told that it won't help. What is the problem?
Apr 21, 2016 at 8:38 AM
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CARADIODOC
  • ✓Experienced Mechanic
  • 34,412 POSTS
You're right. The booster just makes the brake pedal easier to push. There is air in the lines, the master cylinder has a leaking internal seal, a rear drum brake is not adjusted up far enough, a rubber flex hose is expanding due to a torn outer casing and reinforcing thread, (not very common), or a front caliper isn't seated properly.
Apr 21, 2016 at 9:00 AM
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