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1985 Nissan 300ZX NA - No Brake Pedal


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I have a 1985 300ZX NA.


I just replaced the front and rear pads and rotors, the front calipers, and the master cylinder. Everything was installed correctly. The caliper bleeders are facing upward. We bled it according to the factory manual procedure. The new master was bench bled. 


When the car is off, there is pedal pressure. When turned on, with foot on the pedal, it immediately goes to the floor. It regains some pressure (while on) when pumped multiple times.


When we were bleeding, it seemed the pressure was better on the rear calipers than the front. The front had many small bubbles.


The only part of the system I have not checked is the brake booster, but wouldn't the pedal go stiff if that were defective?


Any advice on what to check next?

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The booster only makes pushing the pedal easier. Thus it is normal for the depressed pedal to drop farther when the engine is started. Just not to the floor.


Fronts are separate from the rears so one may feel firmer than the other.


Make sure all hose connections are tight so air not sucked in on the up swing of the pedal.


Check the pedal has about 1/16" of play by pushing down with thumb. There must be a slight play.



Bleed the master on the vehicle by pumping several times to build pressure, holding, then opening the bleeder on the side. Put a clear vinyl tubing over it and into container so it doesn't shoot all over. Just to be clear, tighten the bleeders before releasing the pedal back up. Repeat till only clear fluid comes out.


Do the rears next.


Again pump several times to build pressure and bleed the two rears till only clear fluid comes out. If air is in there it may take 5 or 6 bleeds to move it all the way back to the calipers. It should spurt out quite forcefully. Make sure the master stays FULL!

Bleed the fronts the same way.



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