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Q: brakes

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When I press on my brakes it sounds like air and it goes to the bottom easy. I replace master cylinder, brake lines, wheel cylinder, caliper. It is was bleed and still doesn't stop correctly that is when i heard the air noise when pressing down the brake pedal. I not sure if my brake booster has a leak or if my vacuum line is messed up. my truck is a 1997 Dodge ram 1500 5.9L and it has 4x4 I put way to much money into the brakes to make it not work . Not even sure if it is all 4 abs or rear abs. How can I test to see if my brake booster work also? But what do you pros think is wrong with it?
My car has an automatic transmission.

Hi Joseph: A malfunction in the power brake booster would not cause a low pedal or excessive pedal travel. With regard to ABS, look for wheel speed sensors at the wheel hubs. If there is wiring to any of the wheels, to a wheel speed sensor, that means you do have ABS and consequently you have to bleed the ABS system components in order to expel all air. If your vehicle is equipped with anti-lock braking, you have to either bleed the ABS pump and valving (per Factory Service Manual instructions) or use a bi-directional scan tool to remotely actuate the ABS system during brake bleeding. Otherwise, in an ABS equipped vehicle air will remain trapped in that segment thus causing a low brake pedal. If you do not have an ABS system, the only explanation for what you are describing is trapped air, an internal leak within the master cylinder (of course look for external leaks, but you have probably done that already), or possibly bulging rubber brake lines. If you have a firm pedal and yet inadequate brake pressure at a wheel cylinder, that would be due to a proportioning valve fault and/or a line blockage. If you desire the brakes be bled by a certified Mechanic, dispatched by YourMechanic right to your location, please request a brake system inspection/diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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