I replaced all calipers and just replaced master cylinder.
Before i replaced cylinder my pedal went straight to floor with truck off and while running
I just replaced the master cylinder and now with the truck off i get a good firm pedal but as soon as i start it and get the booster help the pedal goes straight to floor.
I dont know if its just how the truck works or if its because i need new rotors possibly they are still stock 220000 miles
I have tried to bleed brakes but without proper help.
Not loosing fluid. Im curious if the old rubber brake lines really can swell up and make pedal go to floor. Again hard to check without someones help pushing brakes for me
2002 chevrolet silverado k2500hd 6.0 v8
I replaced all calipers and just replaced master cylinder.
Did you use brand new OEM?
I just witnessed someone install refurbished parts the other day because they were cheaper. He got it all back together and they leaked right out of the box. He had to go back to the store, buy the new ACDelco, and do it all again. The brakes worked perfectly after that.
as soon as i start it and get the booster help the pedal goes straight to floor.
I dont know if its just how the truck works
The pedal should sink a bit, but not to the floor.
because i need new rotors possibly they are still stock 220000 miles
Original rotors would be non-existent after 220k. You should probably check them (surprised you didn't look at them while you were replacing calipers)
I have tried to bleed brakes but without proper help.
do it properly, or you will have a bunch of air in the system
Im curious if the old rubber brake lines really can swell up
after 21 years, absolutely. Just replace the flex lines.
If that vehicle has ABS you probably need to use a bidirectional scan tool to properly bleed the brakes. (Tech2 or equivalent for GM of that vintage.)
if the break fluid level didn't change after your tests, you most likely have residual air in the system. Best to use a vacuum bleeder or you can buy self bleeding brake bleeder screws that will stop air from entering the system when you lift your foot off the pedal. The are not cheap, but all parts stores have them. I have a 1999 silverado and a notorious place for the brake line to rust out is right over the fuel tank. Hard to see, but a receding break fluid level should give you an indication if you have a hole in the system or not.
The other option is that you have a vacuum leak, mby at the booster? You would have to test it when the engine is running and you are pressing on the brake pedal.
Its a brand new master cylinder
The pedal doesnt necacarilly sink but i can push it all the way down and hear vaccumn hiss from booster when push that hard
The rotors are only about 1/8 gone i did check them just didnt feel need to replace
I thought possible vaccumn leak but it passes the test.
It gets more pressure when moving and get good brake stop. Just not sure if its normal function for these trucks to be able to push pedal to floor only when its running but i can build tight pedal pressure when its off
Its a brand new master cylinder
and the calipers?