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Alex, ASE Master Technician
Category: Car
Satisfied Customers: 1158
Experience:  ASE Certified Master Technician, L1 Advanced Level Specialist
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Pads..the calipers, I get a hard half pedal after removing all the air

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Installed new front rotors, pads and calipers. When trying to bleed the calipers, I get a hard half pedal after removing all the air. When I start the engine I cannot get the pedal to pump up. What am I doing wrong?

What is the model of the vehicle? Also, is the pedal sinking all the way to the floor when you apply the brakes with the engine running?
Customer: replied 6 years ago.

2001 explorer sport trac.

when trying to pump the pedal with the engine running it goes all the way to the floor

Ok so you must still have air in the system. How did you bleed the brakes?
Customer: replied 6 years ago.
I bled them without the engine running. Had my wife pump the pedal slowly a couple of times and hold it. I started on the RF side, cracked the bleeder screw a little, let it flow a little, watched for air, tightened the screw. Worked at the RF side until the was no more air. Went to the LF side a repeated the procedure.
Id like you to try gravity bleeding the brakes. Crack both bleeder screws on the front wide open and let them drip by themselves for 10 minutes while keeping the fluid reservoir topped off. Make sure not to let the fluid level get too low while bleeding or air can be drawn in through the top. If the system is completely free of air and the pedal still sinks, you may have a failed master cylinder. A master cylinder on its way out will sometimes show its true condition after a brake job has been done.
Customer: replied 6 years ago.
I will give it a try. what effect does the engine have to do with the brakes? i am confused that they pump up and won't with the engine running. thanks
The pedal feels hard with the engine off because there is no power brake assist. The power brake booster uses engine vacuum to make the brake pedal easier to push. I'm sure if you were to hold the brake pedal down firmly with the engine off you would feel the pedal sinking slowly to the floor.
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