I have a hydrovac on my '61 that has never really worked since I added it a few years back. It has remained installed, but with the vacuum line disconnected. When it's hooked up and I step on the brake, the engine dies. I figure there is a vacuum leak somewhere.
I have a hand vacuum pump that I use for bleeding and I connected it to the vacuum connector on the booster and I can get it to hold vacuum without issue. It will hold for minutes, until I release the pressure. So I think the diaphragm is good.
I re-set the ignition timing and put a vacuum gauge on the intake manifold and I'm getting between 17" and 18" of steady vacuum pressure. So I should have enough vacuum.
There is NO check valve on the hydrovac, and I know that I need to address that to preserve the diaphragm, but I'm wondering if the lack of a check valve would cause the engine to die and the unit to not work.
Any ideas on how I can figure out why the unit is giving me headaches? What else can I test to determine why it is not working?
