Brake booster makes air leak noise when cold

[zachattack_5491]

As far as I know it's the stock booster on a '90 s13. It does it ONLY when below 40 degrees, and stops when I touch the pedal and after warming up a bit. The hose isn't leaking and the check valve is good and clean. As far as I can tell the booster works fine. No difference in pedal feel at any time while running. Vacuum stays the same at about -36cm/hg while warming up. A little low, but there's no other leaks and I'm at about 5300ft so it's not too far off. Now obviously I could just replace it, but they're a little more expensive than I'd expect and I'm unfortunately very poor. I don't want to replace it if this is normal behavior especially since I don't notice any ill-effects.

[compactfean]

Id say its on its way out. Just waite till it starts leaking all the time, then replace it.