Thread: Power Brake Booster

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I just bought the car after it sat for 8 years. Just replaced the master cylinder and most of the rear brake lines. It has a decent cam that is only producing 12" of vacuum. So I went ahead and put a can on it. No real noticable difference. I hooked my Mityvac to it where the hose attaches and it won't pull any vacuum at all. I'm guessing it's toast. What do you guys think?

Originally Posted by mrbigg

I just bought the car after it sat for 8 years. Just replaced the master cylinder and most of the rear brake lines. It has a decent cam that is only producing 12" of vacuum. So I went ahead and put a can on it. No real noticable difference. I hooked my Mityvac to it where the hose attaches and it won't pull any vacuum at all. I'm guessing it's toast. What do you guys think?

I would believe that the hand pump moves too small of a volume of air to test with. Use the vacumm from the motor and run it to the booster and remove it and the check valve that you KNOW is WORKING I assume and see if there is a large movement of air into the booster. If it is leaking there will be no change when you remove the hose and check valve. Another test I here all the time is to put your foot on the brakes and start the motor and a good booster will see you foot pedal drop a little more when the motor is started. I went through all these on my street rod with a new master and gbooster that was on the truck for over a year till it was ready to run and was bad at start up and had it rebuilt. good luck ED ke6bnl

Shot in the dark here, With out seeing this system perform or not, I'm gonna suggest going to a smaller booster that Ford used to run a couple of decades ago. the samller the booster, the quicker the recovery on vacuum. I ALWAYS suggest using a vacumm pump driven by the engine. Too many available so installation and adaptation is quit simple. Budget minded builders can also consider using an older style deisel pump from the late 70's and early 80's. pretty plentiful and cheap, rebuild kits still affordably available. Options are out there. But, as I always believe, find and stick with the base of the problem and then create your solution. I'ts easier than you think. Hope this helps.