Hello all...

I've searched around the forums and the interwebs about my issue, but the symptoms don't quite match what everyone else seems to have relating to the brake booster failing...

Immediately following startup, and continuing until a couple seconds after shutdown, you can hear a loud vacuum leak coming from the brake booster area... BUT, unlike other's symptoms, my brake pedal is not hard to press at all... It seems to act the same as it always has, I noticed to change in the feel from before the vacuum leak sound until now...

So, does this still point to a failed/failing brake booster, or could this be something simpler, such as a valve or seal or line?

Thanks in advance for the help!

 

Id remove the vacuum supply line to it and plug it the start engine see if you still hear it. But from what you saying sounds like its leaking . There only one other thing around brake pedal would have a vacuum cruise cut off switch mounted on pedal arm if you have it.

 

Pulled the line and started the Jeep... Hiss went away, and idle RPMs jumped up to about 1.2K... Idled normally before around 600-700RPM...

I don't have any cruise control system on my Jeep, so...

Is this a typical behavior of a brake booster? All I've known them to do when they leak is make braking harder, since it is no longer assisting in the braking process...

Thanks!

 

High rpms because ya gotta plug the line. Id plan on a booster swap soon...
.

 

Or could be in the valve, or whatever you call that part that connect the booster to the line...yeah, I think its a one-way valve? known location for cracks...

 

My thoughts exactly. Valve not seating in the grommet or bad valve.

 

The guys are right. I would change the check valve in the Booster
before changing the Booster itself. Even if you have to change the booster, it is a good idea to change the check valve also.