I have a 86 K20.

My brakes were working fine and then all of a sudden they started to go to the floor without applying any brake pressure. Now they work only at the last 1 inch prior to the floor.

I have replaced the master cylinder and made sure there was no air in the lines...

What else could it be? Any help would be appreciated.

brakes arent bled correctly.

Hmmm, we did that and still not right.

Could there be a pin hole in one that could cause this?

I have bled brakes before and followed the right way this time as well...

so you bench bled the master cylinder, used a vacuum pump to pull fluid all the way through the lines while filling the M/C up so it didnt get sucked dry, after bleeding the lines at the prop valve?

Yes... That is why it is weird, should have been a fairly quick fix for a few hours has turned out to be a very puzzling endeavor.

If we can't get another option, we are just going to redo everything again.

Just not right...

well, go back and bleed it again.

if the pedal is soft, you either have air, or a leak, which is introducing air, which, by the way, makes the pedal soft.


edit:
if you cant see a leak with 700 or more PSI of line pressure, you either dont have one, or you have air.

Roger that, we'll bled the lines again...

Thanks...