Hey guys/gals just wanted to reach out as I’m looking for some advice. I just had my brake booster going bad and I replaced it today. I’ve done all the test on the new one to make sure the vacuum seal is holding right and it seems to be passing those test, but I am still hearing air leakage when I press the brake pedal but that is the only time I hear the sound it’s not making a swoosh sound any other time.
So I’m just looking for advice because my brakes seem to be working properly and my pedal is back to normal and not hard to push like it was Friday night.
And I was also curious about the boot on it, because my original had a rubber boot on it and this new one does not it’s open (pictures below). So is this a big deal or no and could this chase me to hear the vacuum release more?
Thank you in advance for your help!

Original brake booster push rod

Newly installed brake booster with no rubber boot.

 

I had an air leak on between my booster and master cylinder, on the bottom side, which you could only hear when you first shut off the car. Maybe this is what your hearing, it's a common problem, the seal/gasket goes bad.