Q: Brakes don't work properly

asked by on

We have replaced the master cylinder and bleed all the brakes and when the car is off the brakes are firm but when the car is running the petal is soft and it goes to the floor and don't come back up like it don't have any back pressure
My car has an automatic transmission.

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 desire that 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.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Brakes don't work properly

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: I can't remove the rear brake drums.

You should use heat to the drum around the hub and then spray rust penetrant spray on the hub and drum holes. Make sure you have loosened the brake shoes so you can get drum off. If still cannot get...

Q: Q: Car leaking power steering fluid

The serpentine belt rides on some pulleys that are smooth. If you do have oil leaking onto it, it is possible for it to slip off. The rack and pinion is located close to the firewall of the vehicle and...

Q: Q: Cooling fan not shutting off.

There are many vehicles today where it is normal for the cooling fan to run for a few minutes after the engine has been turned off. It is especially long running and will be more noticeable on really hot days...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...