Brake issue again

[IH444t]

So I don't have the Rabs system on my truck and 3 months ago adjusted the rear drums so they stopped locking up before the front engaged. Now the fronts are back to not working and I can press almost
To the floor and stop or lock up rear and no front brakes. It doesn't lock up often, but there is no front brake dive. The tears are backed off enough where I barely have parking brakes.

Someone told me the booster is going bad since it makes a swoosh of air noise.
Master cylinder replaced 2 years ago.
If there is anymore information you need, I will try let you know.
Thanks for the help.

 

[madpogue]

So you removed the RABS valve? Or was it removed by a PO?

Have you bled the brakes?

M/C could be failing internally.

 

[IH444t]

Rabs removed by po
Brakes bled and rear adjusted.

Okay so the mc could be going bad, anyway to test?

 

[crash-harris]

If you get the "swoosh" noise from your vacuum booster, I bet if you get your head near the booster and lightly press the brake pedal you'll also hear a hiss.