94z07fx3

All,

I'm bench bleeding a new (reman) brake master cylinder. The front port bleeds normally with no problems what-so-ever.

The rear port won't bleed not even a drop comes out.

I'm puzzled.

I've tried putting a suction bleeder on that port and it can't pull out a drop either.

I tried putting it on the car and using the brake pedal to push the piston and still the same thing..front no problems rear nothing comes out the port.

Please help.

ETA Update see post four.

Frizlefrak

It's defective.

JackDidley

Take it back.

94z07fx3

Update:

So on a hunch I connected the front circuit to the hard line while leaving the rear on the bench bleeder tube fed back to the resivoir. And we're in business! The pedal made a normal amount of fluid come out the rear port while the front was connected to the hard line. Took it back to the bench to eyeball it further as I was suspecious.

Now both ports bled fine on the bench but I'm out of energy to fiddle with this tonight.

Thanks for reading my post and the replies too. I did think it was (and it may still be) defective.

Cheers!

pcolt94

Just on a guess, I think one of the pistons is on a spring return from the main rod. Perhaps or sounds like it might have been stuck in the pushed or forward position and not returning to its start point so it can pressurize. It might be free now and chamber filled with fluid.

So with it now lubricated and in proper position, it may all work now.

94z07fx3

I had time and motivation to get back on the 1992's brakes today. I thought I'd post this bit about the pressure differential switch.

If the pressure in one circuit drops suddenly this switch is closed and it illuminates the brake lamp on the dash gauge cluster.

If repairing the leak and refilling the brake fluid does not center the switch and reset it then you can do the following to center the switch and turn off the lamp.

Working with an assistant you bleed the circuits at the master by having the assistant press and hold the pedal while you open the line (using a catch rag naturally). When you open the circuit that didn't fail it will push the switch back to center. It may take a couple of push pedal hold open line close line release pedal cycles to get it to move.

In my case the switch wasn't set by a failure but rather by my effort described in post four to get the rear circuit to bleed.

So with the new master and new soft lines at each wheel and with all the fluid flushed and air out the brakes are working well.

Cheers!

pcolt94

Should have suggested centering the proportional valve as I have before in the past, I just overlooked it this time.

But good job getting it done. Good method.