Brake Booster Question - Is this a leak?

[redsn95gt]

When i had my engine bay stripped out for painting I decided to replace my rusting brake booster with a replacement piece from pep boys. Think I paid about $80 for it with core. Anyway, its a rebuilt model.

So as I am bleeding the brakes getting it ready to test drive, I'm discovering my pedal feel wasn't the best, soft mushy, going to the floor. Then I noticed when I depressed the brake pedal, I was hearing a air hiss. This hiss was coming from the vac hose attached to the brake pedal that has the valve that opens when you depress the pedal. So for giggles, I pulled the hose and valve off the pedal to mess with it. With the valve off, the hose is sucking air all the time, causing the hiss sound, and of course the valve opens it when its pushed in. Plugging the hose up while i push the pedal feels better, although its desperately trying to still suck air. My question is, is this normal operation? I don't recall if this was like this before I took the car apart so long ago. I also tested the cruise control switch on the brake pedal, didn't change anything, I removed the cruise control stuff from the car completely so the switch is probably useless now.

Is is possible to hook up the vac canister wrong and have a problem like this or is my brake booster faulty? I'm NOT looking forward to pulling out that booster again!

 

[VibrantRedGT]

A faulty brake booster is the opposite of what you described. The pedal would be rock hard. Now if the vacuum line going to the booster was bad you will have weak brakes. A very mushy soft pedal is the master cylinder. When you bled the system there might be more air in the line, this causes a soft pedal too. If all the air is out and still having the soft pedal it will be a faulty master cylinder.

 

[Adam95GT]

Did you bench bleed the master?

 

[redsn95gt]

No, I did not bleed the master itself. I can do that tomorrow. Would this all contribute to the vac line at the pedal?

 

[revhead347]

The switch on the vac hose attached to the brake pedal is for the cruise control. What you described is normal operation. That switch has nothing to do with the brake booster. The valve for the brake booster is internal to the booster. The mushy feeling is probably just not what you are accustomed to, and indicates a very good brake booster. The vac canister in the fender is also for the cruise control, and has nothing to do with the brakes.

Kurt

 

[redsn95gt]

Solved this problem just wanted to post my solution-

Bled the system using a harbor freight pressure/vacuum system that hooks to your air compressor. Its a knock of the more expensive units, this one worked fine for me, sometime harbor freight stuff is hit or miss.

Anyway, bled all 4 wheels in order RR,LR,RF,LF 2x. Did not bench bleed my master cylinder, read to try this first with the pressure system. I also used my little "one man" bleeder to confirm there was no air bubbles coming out the bleeder valves. 2 rounds and the thing was solid.

I did have a brake leak! I didn't notice fluid squirting all over the inside of my wheel. That was why my system wasn't pressurizing before. I had installed my rear passenger banjo bolt washers incorrectly. After fixing, leak went away and it was easy to fix.

Thanks all for the suggestions and help

Ryan

 

[Chythar]

Obviously the fluid leak was causing your soft pedal that would sink to the floor. Good thing you caught that before you went for a test drive!