Bleed brakes the pedal is hard then after I start it the brake pedal goes soft
Ok what else did you do ? Check these things look for leaking lines calipers wheel cylinders, did you replace the master cylinder if so did you bench bleed it first if not you must do this first hopefully you haven't blown the primary seals in it already, are you following the bleeding process, the farthest wheel first from the master cylinder //// (RR) (LR) (RF) (LF) AND DID YOU PRESS IN OR SWITCH THE PROPORTIONAL VALVE?MOST TIMES THE BRAKE BOOSTER WILL GET SUPER HARD TO PRESS THE PEDAL UNLESS THE SPRING INSIDE BROKE BUT I DON'T THINK SO IT WOULD REALLY HELP US ALL IF YOU TOLD US WHAT HAPPENED FIRST AND WHY YOU CHANGED THE BRAKES AND WHAT ELSE YOU REPLACED
Possiable brake booster. if you hear a hissing sound and truck runs rough if not possiable master cylinder.
SOURCE: 1999 GMC Sierra brake problem
When you change the master cylinder it is best to gravity bleed first, then proceed to the pedal technique.
Gravity bleeding is when you just open the valve and let gravity pull the fluid down.
Keep in mind you must "prime" the master cylinder first before installing it, did you do that?
Priming the master cylinder is where you put it in a vise gently, you then take apaptors and screw into the outlets, then take tubes from the adaptors back into the resoirvor. You fill the resorvoir up with fluid and take a 3/8 extension for a socket and push the piston in and out slowly until there are no more air bubbles.
After this procedure you gravity bleed the brakes, then go on to the pedal technique.
SOURCE: 2003 GMC Sierra Brake PROBLEMS!
Try vacum bleeding with a vacum pump from any parts store. You definitely have air somewhere and vacum bleeding usually works and you can do it by yourself.
SOURCE: excessive brake pedal travel
Do you need new pads? Did you try to bleed the master cylinder? Are you sure you bled the system correctly? Excessive travel is almost always air in the lines of not enough brake fluid.
SOURCE: brake pedal goes down to far abs brakes
Hi I'm litoshop if you bled the system and get no results then your brake pump needs to be replaced now before replacing make sure your pads are installed correctly because if there not this to can cause this problem good luck. if this information has been useful please let us know thank you.
SOURCE: Brake pedal still goes to floor 2000 GMC Jimmy
It's very possible to be the master cylinder, the o-rings on the piston could be worn, letting the fluid seep back through instead of getting full pressure through the lines. Could also be the brake booster.
Try changing the master cylinder first, which is cheaper and easier, and see if there is a difference, you'll need to bleed the brakes again.
To check the booster,
With the engine off, pump the brakes until the pedal is hard, then hold pressure on the brake pedal and listen for air escaping, or the pedal goes slowly to the floor, Do that after the master cylinder has been changed, at least that will be eliminated.
Testimonial: "Hadn't thought about the O-rings on the rod thanks for the idea. Great Idea Thanks!"
423 views
Usually answered in minutes!
×