I had new brakes put on and now the brake pedal goes all the way in and is hard to stop. Could not bleeding the brakes cause this issue. With the truck off the brake pedal is firm so I didn't think it was the master cylinder. Please help
My car has 190000 miles.
My car has an automatic transmission.
If the hydraulic system was opened, for example, if rebuilt calipers were installed, then yes it could very well be that the entire four wheel system needs to be carefully bled, preferably using a pressure bleeder, and also being mindful of the fact that you have ABS. Sometimes a bi-directional scan tool has to be used to remotely actuate the ABS system to "expel" trapped air in ABS valving if lots of brake fluid has drained out during service. If the brake fluid has been in your vehicle for 4 years or more, you should bleed all four wheels anyway because brake fluid loves to collect moisture from the air; this moisture both corrodes the system and ends up partly as air bubbles, if and when brake fluid reaches about 212 degrees. So, if the system was opened, or the fluid is old, yes, absolutely, it has to be thoroughly bled at ALL four wheels.
Another possibility is the calipers have not yet fully extended to create close pad rotor contact and it is also possible that you have stuck,or inadequately lubricated sliding pins in the caliper torque plate. Generally, after 75,000 miles rebuilt calipers should be installed as these parts just have too much potential for sticking and other problems as they age. Really, a brake "refurbishment" is best done with new rotors, loaded rebuilt calipers from a reputable vendor (not easy, but AC Delco, etc. are OK) and a thorough flush of the hydraulic lines with new brake fluid. With that approach, you won’t have any headaches.
If the system wasn’t opened, and the caliper piston was forced inward, without opening the caliper bleeder screw to relieve the pressure, hydraulic fluid - possibly contaminated with dirt and sludge - ends up getting forced backwards up into the master cylinder or other components like the proportioning valve. There are reports that this "could" create problems (for the master cylinder and valving) and thus the safest practice is to simply open the bleeder screw while forcing the piston back but again even that can be avoided if rebuilt calipers are used which is highly recommended after 75,000 miles.
During a mobile visit, a certified Mechanic from YourMechanic would be glad to inspect the brakes and resolve this issue for you. Please let us know how we can assist you further and if you have additional questions.
Have a car question? Get free advice from our top-rated mechanics.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing