[Autoengineer]

I watched an episode of "Muscle Car" a week or 2 ago and he put a vacuum pump on a brake booster. He showed that you should be able to get a vacuum reading. It won't pump up quickly like a canister, but after at most 20 pumps, you should get it to hold some vacuum. well mine holds no vacuum no matter how many time I pump it. Looks like I have a bad booster. That looks reasonably easy to change, but how much do you guys think this has been throwing off my A/F and vehicle performance?

 

[overdriv]

If your brake booster is bad, I would think you would have a hard pedal.

Also, if your booster is good, it will hold vacuum for a long time, providing the check valve and grommet are good. Pull the check valve out of the grommet in the booster, you should hear the air rush in.

The brake pedal rod has to be adjusted correctly for it to work properly also.

 

[Autoengineer]

If your brake booster is bad, I would think you would have a hard pedal.

Also, if your booster is good, it will hold vacuum for a long time, providing the check valve and grommet are good. Pull the check valve out of the grommet in the booster, you should hear the air rush in.

The brake pedal rod has to be adjusted correctly for it to work properly also.

The pedal is hard, plus I can't lock the brakes up. Actually, the car brakes OK around town, but no matter how hard I push on the pedal, I can't lock the brakes. With discs up front, I figure should be able to lock them up.

 

[Autoengineer]

So I tried a little experiment today. Pulled the vacuum hose off the brake booster with the car idling and the car immediately shut down. Obviously, the booster must be at least impeding the flow of air because its allowing the car to run. I think I'm going to take this in and have someone look at it. They can bleed the brakes when their done too. After my cracked head issue and the then the recent cam swap, I think I've used up all my mechanic-mojo for the rest of the summer. :yes:

 

[acny1973]

It shut down because you created a huge vacuum leak with that hose opened. You wouldn't be able to stop the car if the booster was that bad. Maybe its kinda worn out but its not shot if the brakes worked.