I have a 1998 jeep grand Cherokee, the brake booster went out and i replaced it, now after a miles of driving the brake pedal gets rock hard and the brakes start to apply themselves and bring me to a stop, i have to pull the vacuum hose off of the brake booster and wait a few seconds and the brakes will release, then it's good to drive for a few more miles, i have also replaced the calipers, rotors, hoses, pads, and master cylinder hoping that one of those things would fix it, it didn't, I'm still having this issue and i need help.

 

I say check valve from vacuum like to the booster


Maybe, anyway its one way valve so if you blow in it, air will pass, if you dare to suck on it, you should get nothing.


If not that my other guess would be something to do with the push rod length inside the booster?

 

Yeah, I'm betting pushrod length. I'd talk to a brake shop to find out what it should be.

 

Hum. If the problem started after you replaced the booster, I would start by putting the old booster back on. May I ask what prompted you to replace that? I guess they may go bad but I have never seen one.