and your positive that the vacuum line doesn't have a leak in it, or the rubber fitting between the vacuum line and brake booster doesn't have a hole in it????

I would look at the cheap parts first.

 

Did ya get it fixed?

edit...edit... I should check the date on the post before I ask.

 

mine made the noises. A vacuum diaphragm busted, in the power booster, i believe. It began to get a fluctuating idle, especially when I would press the brake. replaced the brake power booster and all stopped. really easy to change out, just kinda hard to get to the bolts right above the brake pedal.

 

going to buy booster today, last nite i looked up under the dash and had a hard time finding the 4 bolts, there is the carpet, and some blackrubber stuff, i mite just cut it away. i'll keep you up dated and might even take pic... kinda like a mini school "101 BOOSTER REPLACEMENT"

 

ok... i'm down to 1 last nut, it is behind the steering bracket ... i'm sitting here thinking of how to get it out.. think think
i think i need to think some more, any way here is a pic on what you need to take off to get under the dash

i'm not going to let a little old car beat me !!!

[IMG]local://upfiles/3527/6FF79D20EF18400DB32A9F41BAFA51F0.jpg[/IMG]

 

i have a question on this, i have the same problem and it is the booster, but how do i get the brake pedal disconnected from the switch. it seems to be some sort of strange bolt connection

 

My first gen you just unbolted the cover part on the petal and had a cotter key in the rod. Took that out and the rod slide off the petal.

 

2 things:
1: this post is 1 1/2 years old, you would do better to just start another post.
2: if you don't put in your vehicle info and we don't even know what year it is, how can we give you a correct answer.

Now I can answer the question 'cause I've just vented some frustration.

On your '98 Blazer, there is a clip that you have to spread and then push to get it off the pin on the brake pedal, then the brake switch can slide off and the push rod comes out with the power brake booster.
Sorry I don't have a pic of the clip.

[IMG]local://upfiles/2910/4E5963DC53BF4650B6867AA5132A5E7D.gif[/IMG]