would air in the brake lines cause a sqeak/creaking kind of sound? my truck is making this type of sound but only when i apply the brakes and can only be heard at low speads...i've tried hearing the sound under all types of different conditions and its only consistent when braking and right after releasing the brakes. And as a little side note, I've tried going through bumps/dips at low speeds without braking to see if its the suspension but the sound is not present here??? so im confused...any help is appreciated..thanks