Soft brake pedal to floor

MUDRAT652

MEMBER
1994 GMC SIERRA
5.7L
V8
4WD
AUTOMATIC
122,000 MILES

All right here's what's going on. First, I am getting new knee in 2 weeks have bad back and been out in garage for last two weeks doing everything I can think of? Am 66 years old, been mechanic all my life and very seldom get defeated in a job but this has done it.
Started off just new front pads and turn rotors--Put on Bosh perfect-stop pads
Oh, brake pedal never was good but could slide tires on gravel road okay.
Now no brake pedal? Hard when engine off to floor when on?
New master cylinder, then that was bad [leaked at reservoir seal] took back then put up-graded new style master cylinder on, no change?
Took to shop to power bleed they found combination valve leaking
Took back home I took off ABS and put on new combo valve bled and bled and bled the system there is no air in this.
Oh, put new rear cylinder on last year checked and adj, they're okay.
Now took out on my gravel road with all this new and the pedal goes to floor and cannot slide tires on stone road.

Well, one thing I'm sure of it has all new fluid, I ran four quarts through it in all and just keep getting air and air out of all the bleeders. As far as ABS it is gone anyways took it off, and I could not drive it and stump on pedal and lock wheels. That's what I'm saying I can't even slide wheels on a gravel road. Really! I have no brakes even when I do get a little pedal. The shop I take it too is small shop in small town and they do me right, they had it two days and three guys work on it on and off only charge me $100.00, and that's when they found combination vale leaking so I took home put new one on.
I have a new booster coming and new rubber lines and another new master cylinder [old type] that will be all new parts and no ABS so we will see, I guess.

Well, just picked up truck from shop and after new rubber lines, new booster, new master cylinder, third one, and another set of new front pads and $420.00 later I still can't, I mean can.

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,454 POSTS

Hi,

I need clarification. In your last sentence, you indicate. ". And $420.00 later I still can't, I mean can." Are you referring to sliding on gravel?

Also, if there are no leaks, the parts are all new, and there is no air in the system, they should work. However, I need to know if the ABS module has been removed. If not, did it have 4-wheel ABS or only rear? If it has 4-wheel ABS, I attached the procedure below for bleeding the module. Also, the last pic explains the procedure for only rear ABS.

Let me know.

Joe

See pics below.

Images (Click to make bigger)