A neighbor brought me his 2000 Ford Ranger 4wd 4l V6, power brakes & steering. He said his brake pedal was not as high as it use to be. I pulled the back drums, shoes were good, adjusted the rears, quite a bit. I checked the brake pedal and it was low! I don't trust this man. He said it was higher before I adjusted the brake pedal. I should have checked the brake pedal before I adjusted the rear brakes. I suggested let's bleed the brakes as it has never been done. Fluid came out discolored but no air bubbles. Bled all four until the fluid was clear. The brake pedal came up! I had him start the car and the pedal sunk down almost to the floor. Turned the car off and the pedal came up, started the engine and it sunk. I told him I think it's the power brake booster. ???? He then drove 4 houses home, called me and said the pedal was back up. Is this the master cylinder or is this the booster? Should I replace one? Or both?
Should master brake cylinder replaced after low pe
- Thread starter JLawrence08648
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I'm guessing the booster, if the master cylinder was moving like this, you should be loosing fluid and taking in [censored] a lot of air.
Does it work when the pedal is back in normal up position? Got brakes? Do brakes stop vehicle when pedal in down position?
After you adjusted the Rear, did you drive it in reverse and slam brakes to a complete stop, so adjusters can tighten up?
Does it work when the pedal is back in normal up position? Got brakes? Do brakes stop vehicle when pedal in down position?
After you adjusted the Rear, did you drive it in reverse and slam brakes to a complete stop, so adjusters can tighten up?
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I had a 2001 Ford Taurus that did the same thing. I believe the seals inside the master cylinder goes, so you don't see any brake fluid leaking out, but the pedal goes to the floor. I would think if the booster was bad, you wouldn't get any braking power, not the pedal going to the floor. I replaced the master cylinder and it was fine afterwards.
Those are not symptoms of a bad booster.
A defective brake booster will have one or all of these symptoms.
Hard pedal (no boost, can also be a vacuum line)
Longer stopping distance due to reduced boost
Engine stalling due to vacuum leak cause by a damaged diaphragm
It could be a bad master cylinder bit I would suspect some fluid loss into the booster in the rear of the cylinder if the fluid was bypassing the seals and the pedal to sink slowly to the flow if pressure is maintained on the pedal.
Drive this vehicle and slowly engage the park brake and see if that brings the pedal up. You may be dealing with out of round drums and/or not enough adjustment. An out of round drum with have a higher or lower pedal depending on where it stops.
When you rotate the drums by hand they should have a uniform contact sound from the shoes if it gets a little tighter then loose and tight again the drum is out of round.
A defective brake booster will have one or all of these symptoms.
Hard pedal (no boost, can also be a vacuum line)
Longer stopping distance due to reduced boost
Engine stalling due to vacuum leak cause by a damaged diaphragm
It could be a bad master cylinder bit I would suspect some fluid loss into the booster in the rear of the cylinder if the fluid was bypassing the seals and the pedal to sink slowly to the flow if pressure is maintained on the pedal.
Drive this vehicle and slowly engage the park brake and see if that brings the pedal up. You may be dealing with out of round drums and/or not enough adjustment. An out of round drum with have a higher or lower pedal depending on where it stops.
When you rotate the drums by hand they should have a uniform contact sound from the shoes if it gets a little tighter then loose and tight again the drum is out of round.
It's been my experience when a booster fails the pedal gets high and rock hard. It sounds like the master cylinder is developing internal leaks due to seal deterioration which will cause a low or sinking pedal.
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Sounds like the Master Cylinder, they are cheap make sure to get a bleed kit.
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