Brake Question

Hi Chip,
Is it the original booster? If so the rubber diaphram is probably getting stiff and the unit needs to be replaced. You can probably disconnect the vacuum line and put a pump on it to see if it's ruptured but as you pointed out the unit wouldn't work after words and the motor would be running ruff from the vacuum leak. My best guess at this point.

Steve

You have a few things to check.

Since the system requires vacumn to operate, you might have a vacumn leak somewhere in the motor. Also a radical cam or engine will provide lower vacumn so it will take a few moments to build enough vacumn to effect the booster.

Also check the large lines from the engine to the booster, could be a leak in the line.

Lastly, where the vacumn line runs into the booster is connected to a check valve. Make sure that is operating properly and not clogged up.

On my 427 windsor, it will build vacumn but after repeated brake applications the brakes will start to become harder to apply. This is due to the reduced vacumn from the large cam in the motor.

Thanks for the advice...I will check it out and report back

Chip