Datsun Roadster Forum-311s.org

Hey
I just put on the 240sx rear brakes.

I have it out and the brake pedal goes right to the floor.
I bled the brakes, pressure and gravity.
When I pump the brakes I get some pressure and the fluid in the rear brake part of the master goes down and then when I release the pedal the fluid goes up.
I've never seen that before.
Is there still more air or is the master shot?

Just a thought: Did you bench bleed the master?

Yes I did.
Any other reason why the fluid would go down and then come back up?

Did you bleed the master on the car? Bench bleeding just doesn't seem to work for me, and I always bleed it installed. Obvious questions, but did you attempt, or actually bleed at all 4 wheels, and get fluid from each cylinder? Sounds like air compressing and releasing. Is the master new or used? IF used, yes, I would suspect the cylinder might be bad.

Master was bled in the car as well. Fluid is coming out from all 4 corners. "It's coming out of wherever" trump.
It is my own master, so yes used.

Ok then I go with the master being toast. Look inside the driver footwell any moisture? Is there anything introduced into the system like a proportioning valve? Can you bleed that?

Could the bleeder on the master be slightly open?
Linda

I always use a 60cc syringe to introduce fluid from the bottom up. Use silicone tubing to hook up. Probably can get tubing at a hobby shop. Suck most of the fluid out of the master, wrap the bleed screw threads with Teflon tape and go from there. Bleed one at a time, starting at the furthest rear and working to the closest front. Don't overflow the master reservoir. That pretty much eliminates any air in the system. If the problem continues, something is most likely wrong with the master.