brakes wont hold pressure ?

[eklips3]

alright so im in the midst of finishing up a rb25 install into an s13 , everything is finished and then me and a friend discovered a problem while bleeding the brakes....

so we bleed all the brakes properly up until we see no air bubbles coming from the tube.
we get all 4 sides get finished up , then as i sat in the car after the job was done .. i pumped the brake a few times .. had pressure .. waited a few seconds compressed the brake pedal again .. and i can push it all the way to the floor a few times , and after a few times it becomes stiff again .

and once it becomes stiff again , after maybe 10 - 15 seconds i can compress the brake all the way to the floor.


what the hell could this be ?.... brake booster ?

[TTrx7Pete]

Could be a number of things:

1. You still have air in your system. Make sure you bled properly by first gravity bleeding and constantly adding fluid to the master cylinder.

2. Properly bleed each brake line

3. Make sure you have 0 leaks

4. All else fails, you might have a bad master cylinder or brake booster... remember brake booster only operates while the car is running because it uses vacuum to boost your pedal pressure to the master cylinder.