brake booster diaphram?

[jbashaw]

so i been noticing a hissing sound when i push on the brakes and figured it was only leaking when pushing the brakes... i cupped my hand around the push-rod and noticed it sucking air while idling.... this could explain why Im not getting the mileage i would expect... my question is that is there anyway you can just replace the diaphragm instead of replacing the whole thing and would that explain my bad mileage?

 

[blacksnapon]

Nope! Pretty much booster time! Anything with that much vacuum leaking, is going to affect mileage.

 

[bugeye01]

I wonder if that is the same sound I hear? Mine is 1995 F350, 460 CI. I hear a quick shshshsh sound just at the moment I hit the break pedal each time. But I thought 7 mpg was normal for this thing. 8 mpg would be great!

 

[jbashaw]

yeah i thought the shsh sound was normal but one day stuck at a stoplight i realized it was still doing it with the brake held down... so i while idling i cupped my hand around the push rod on the pedal going through firewall and it was hissing so I'd try that and if it is pulling then then it's time for a New one...