1999 silverado brake problem

[Karl]

Hello folks I've been around for a bit and have learned quite a bit here but this one has me stumped. I have a 99 model silverado 1500 4x4. It has the 4 wheel disc brakes and the vacuum assist power brakes. My brake pedal goes all the way to the floor after putting on a new master cylinder and all new brake lines. I bled the brakes like I have always done it starting at the right rear  and working towards the master cylinder. I'm getting fluid at all 4 wheels and  I'm no longer getting bubbles in the clear bleeder line. The brake pedal is still going straight to the floor. This is a real head scratcher to me. Does anyone have any suggestions on what to do next? Thanks for any help.

Karl

[muddkatt]

It has to be either a bad out of the box master cylinder, or you have a leak in the lines or at a caliper.

 

Once you get a hard pedal, you have to hook the truck up to a scan tool and have the ABS "purged".

[davester]

did you bench bleed the MC before hooking up the brake lines to the MC when you replaced it?  Are you sure the rod from the booster is in the correct spot in the MC?

[Karl]

No leaks and I even put plugs in the master cylinder and got a hard pedal so I'd say it's good. I didn't bench bleed the master since i replaced all the lines and figured what little bit of air that was in it wouldn't really matte r. It would all come out in the end.

[txab]

Always bench bleed before installing

[davester]

I used short pieces of old brake lines, just bent them to feed back into the MC reservoir.  no cost and worked fine for doing it.  You can do it in the truck (and then rebleed all 4 corners).

[Karl]

Thanks for the replies. What it turned out to be was a bad rubber hose on the drivers side front. Apparently it was coming apart internally and wasn't allowing the air to bleed out. Changed the line, bled everything again to be sure and have a nice tight pedal. Thanks again.

[davester]

thanks for coming back and posting what your fix was.