1998 Z24. I have bled the brakes and the master cylinder. I can build up pressure with the car off. If I start the car I cannot get any pressure. Do you think this could be an issue with the pressure booster or am I over looking something?
Any comments or suggestions would be greatly appreciated.
Thanks...

Sounds to me you still have air in the system, This what a do, Get a friend or some one to pump the brake pedel until it feels firm, Then, Do this procedure bleeding the brake system, First bleed the front drivers side brake caliper, I usually bleed the each wheel 3 times, Then drivers side rear drum brake bleed, Then Right rear drum, Then right front brake, After that the system should be completing free of air, Also make sure that u dont allow the the brake fluid get low in the master cyl, Then u will have to redo the bleeding process again.

Good Luck.

Did you do any work or just bleed the brakes? Why are you bleeding the brakes? Give us more history and we'll try to solve your problem.

First off this is technically my sons car. In a moment of shear genius he loosened the brake line front the front right tire and pumped the brakes. Why?? Why do 17yr olds do a lot of things. I know he had a sh!t ton of air in the system. I heard that you cannot bleed the master with a mighty vac. Anyone else ever hear of that? I did use a mighty vac and conventional pedal pumping to bleed the system. I did not do the rears. Guess I need to do that. It still seems weird to me that I can build excellent pressure with the engine off, but get a mushy pedal with the car running. Do I need to bleed the brakes with the car running? I have never had to do that on any other vehicle.

I've always bled brakes with the motor off, but I've also always bled them working from furthest wheel to closest wheel to the master. I think you need to do all four corners and that should solve your problem.

Call me crazy, but those pumps SUCK. Much rather grab a 2nd person and bang it out old school.

Just like to add, Ive just finished doing a complete brake job on 99 Z24, I bled all the brakes the way I mentioned above, I didnt have a problem with the with the system yet, All I can t tell you is the system still has air in it.

Agent Omega wrote:I've always bled brakes with the motor off, but I've also always bled them working from furthest wheel to closest wheel to the master. I think you need to do all four corners and that should solve your problem.

Call me crazy, but those pumps SUCK. Much rather grab a 2nd person and bang it out old school.

that.


i have done vacuum bleeding on a ,aster before, but it was a constant vaccum, not a hand pump.
If you opened the master for bleeding, bleed the master first, then go to the wheels, farthest to closest. If there is STILL air in the system, it most likely went to the ABS module, and is stuck there. You will have to bleed this, then the wheels again if that is the case.