i am working on a friends '96 mustang GT with a 4.6 SOHC and he has a squishy brake peddle. when i am under the hood i hear a whisp noise coming from around the power steering reservoir. there are no visible leaks of brake fluid, and there appears to be no air in the brake lines to the wheels.

has anyone else encountered this problem???

any and all advice on this matter would be greatly appreciated. thank you.

 

I take it you already checked the fluid levels? I would also go ahead and bleed them to see if there isn't some air in there. Other than that, I am not sure.

 

yes i bled the brakes, there was no air in the lines. we are thinking it is a bad brake booster.