Ok, there have been lots of questions around the C3 vacuum systems and I have learned a tremendous amount from the group on how to fix the vacuum system on my '69. Now I have a more advanced question - really an observation that I would like to confirm.
I had all the usual problems - droopy headlights, slow up/down motion, not holding vacuum after shutdown, etc. With the help of this board and Dr. Rebuild's testing guide I was able to fix all my problems - and introduced a new one. My wiper door vacuum actuator had a leak in it, so I had to replace it. Since I was prepping the car for a PV, and the PV doesn't much care exactly how original the component was, I elected to temporarily replace my 'coffee can' style actuater with the later style (and cheaper) 'dual pie pan' style. After doing this I hit the dancing wiper door syndrome on initial start after the vacuum system had bled down.
I went back over everything and could not find a problem. As a side project, I tracked down and repaired the leak in my original actuator (turned out to be the hose nipple on the front of the canister, fixed by a thin bead of sealant around the base of the nipple). While fixing that I had an epiphany. Jack and others often talk about how the control circuit and servo circuits of the vacuum system are "tuned" so that the control circuit charges first, before the servo circuit can pop the headlights or wiper door. Could the source of my problem be the smaller, apparently lower capacity actuator that I had installed? As a test, I put my original coffee-can style actuator back on the car and found that the problem had indeed disappeared.
So, my question for the vacuum experts out there is this: Is it possible that the vacuum circuits are tuned so precisely that swapping the actuator can to a smaller style, without compensating by adding additional hose or using some other method to increase the overall capacity of the servo circuit, cause this to happen? Or is maybe my original actuator still leaking just enough to make the servo circuit charge up slower than the control circuit, which would imply that I still have a control circuit leak somewhere?
Thanks,
Jon
#10679
I had all the usual problems - droopy headlights, slow up/down motion, not holding vacuum after shutdown, etc. With the help of this board and Dr. Rebuild's testing guide I was able to fix all my problems - and introduced a new one. My wiper door vacuum actuator had a leak in it, so I had to replace it. Since I was prepping the car for a PV, and the PV doesn't much care exactly how original the component was, I elected to temporarily replace my 'coffee can' style actuater with the later style (and cheaper) 'dual pie pan' style. After doing this I hit the dancing wiper door syndrome on initial start after the vacuum system had bled down.
I went back over everything and could not find a problem. As a side project, I tracked down and repaired the leak in my original actuator (turned out to be the hose nipple on the front of the canister, fixed by a thin bead of sealant around the base of the nipple). While fixing that I had an epiphany. Jack and others often talk about how the control circuit and servo circuits of the vacuum system are "tuned" so that the control circuit charges first, before the servo circuit can pop the headlights or wiper door. Could the source of my problem be the smaller, apparently lower capacity actuator that I had installed? As a test, I put my original coffee-can style actuator back on the car and found that the problem had indeed disappeared.
So, my question for the vacuum experts out there is this: Is it possible that the vacuum circuits are tuned so precisely that swapping the actuator can to a smaller style, without compensating by adding additional hose or using some other method to increase the overall capacity of the servo circuit, cause this to happen? Or is maybe my original actuator still leaking just enough to make the servo circuit charge up slower than the control circuit, which would imply that I still have a control circuit leak somewhere?
Thanks,
Jon
#10679