[Help Request] Brake Booster Vacuum Leak

tony2084

Hi all.

I have a 2009 Z that I had always suspected a vacuum leak from a car having rough RPM, and high short-term fuel trim at idle, but I could never find it. Even had Nissan dealership run a full EVAP leak test to confirm a few years ago and nada. After much frustration of chasing a phantom issue, I decided just to change out all my PCV valves and EVAP solenoid. I sort of push the problem to the back burner since I barely drive the car for more than a few months a year.

That is until recently, I noticed a hiss whenever the brake pedal is being depressed at idle when the car is on and went away again when under load. And when the car is off, depressing the pedal and releasing it will cause an air suctioning sound(?)..

The brakes themselves are still functional, but this recent sound confirms my suspicion of the leak that I've been chasing and its general location. So now I am fairly confident the leak is coming from within the brake booster system or the old seals from the brake master cylinder.

Had anyone run into a similar type of problem before and have any recommendations or ideas about the price before I inspect it further and take it to the shop? Thank you in advance!

Dentt42

I had the o-ring on mine cause an irritating leak a while back:

'12 G37 with Brake Booster Vacuum Leak