Strange sound from brakes

[sneitzel]

Late last week I noticed a hissing sound when I apply my braked semi firmly.

The sound is similar to the pfft pfft sound you get when you are pumping up the brakes while bleeding the lines except this is a sustained pffffffffffffffffffffffffft sound that will hold until you back off the pedal or really jam it into the floor.

I have not noticed a change in the performance of the brakes yet but I want to make sure nothing's wrong. If this is a normal thing, I have never noticed it before and now it is loud enough to be heard over my stereo system.

Any thoughts?

Thanks.

[ConElite]

Kinda hard to understand exactly what that is. Hmm. Have you changed the Fluid recently?

[sneitzel]

No fluid change. I did check fluid to make sure it wasn't low.

Sounds alot like an air leak but only when pedal is pressed down firmly. Soft or really hard and it doesn't make the sound.

[ConElite]

No fluid change. I did check fluid to make sure it wasn't low.

Sounds alot like an air leak but only when pedal is pressed down firmly. Soft or really hard and it doesn't make the sound.

Dang I have never heard of something like that. Is the Hose thats connected to the Brake booster Connected? Sometimes if thats leaking it makes noise. But thats I believe continues vacuum.

[sneitzel]

I guess it could be vacuum. It's coming from the pedal area under the dash so who knows. I'll try to pull the panels this weekend and see if I can find it.

[sneitzel]

Finally got around to ripping into things and sure enough it was the booster. Had to special order one and got it installed it this weekend with only a minimal amount of PITA.

One question. The tag on the rebuilt unit said the rod on the booster may need to be adjusted. I didn't do anything to it and it bolted up without a problem. It seems to work fine (I drove it to work today) but wanted to make sure I didn't overlook anything. The brakes do seem more sensitive now and that got me wondering if that's what the adjustment was. I want to make sure the pads aren't dragging or anything like that.

FYI,
I'm still working on getting all the parts together to do the LS1 swap as well. This problem just needed to be handled first.

[ConElite]

The brakes should be alot more sensitive. You replaced the component that aids in easy brake engagment. That this is basically like a spring helping you push the brakes in. Your replaced it, so its alot more efficiant. The adjustment im sure is just to make sure the rod is long enough to connect to the peddle. As long as everything bolted up your fine.

[sneitzel]

Cool.

I just needed a little re-assurance.

Thanks again for your help.