i recently bought a 75 vette. have replaced a lot of interior items. my headlights work for the most part but drivers was coming up quick and passenger side was slow. installed new vacuum lines and still the same. on the right side, i replaced springs and bushings on the actuators rods and installed a new actuator. right side worked great and did the same to the left. it seems now there isn't enough vacuum to lift both lights. testing showed no leaks in the tank but if i hook up lights one side at a time they work. can i install a tee and bypass the tank or is there another solution. thanks for any help.

Go to http://www.corvette-101.com. Click on "vacuum trouble". Follow the troubleshooting steps and you will find the problem. You'll need a small vacuum pump found at Sears, NAPA or Harbor Freight-about 25 bucks. Maybe you have a faulty actuator relay valve on one side. Good Luck. Bob


made link clickableAdams' Apple2007-01-09 20:45:38

You must have the vac. "tank" connected in order to have sufficient vaccuum to operate the headlights.
Have you checked the actuator itself for leakage? Also, as stated above, the relay valves are notorious for leaking. They are about $50 each, if you want to replace them. You will have to sooner or later, anyway.
If your engine is not producing enough vaccuum, the tank will never be "full", and it will deplete rather quickly. Check the check-valve, at the rear of the intake.(Small, silverish metal valve, with one hose on one side, and two on the other.) You should be able to blow thru the side with two fittings, but not the one with only one fitting.
I can send you some vaccuum troubleshooting tips, if you like. Just P/M me with an e-mail address...

I had the same problem with my 71. A Mighty Vac is a great tool for checking for vacuum leaks. You can get one at most auto supply stores. I replaced the seals on my accuators and the vac lines. They work great. Good luck, Terry

just an update. thanksBR for the corvette 101 tip. excellent guide. have 4 different books and even paid for a trouble shooting guide that don't even come close to explaining what the guide there does. i think most of my problem was on the right side. everything seemed fine but figured i'd change all the bushings. pins where springs connect were so full of dried up gook that i had to take the linkage out and knock the pins out with a hammer. cleaned them and installed newbushhings and reinstalled. started car headlight still not coming open right but now they both close easily. i believe that Br & adam are right about the relay valves being bad. vacuum reads a very steady 18 on the vacuum gauge so that is not a problem. will test relays tomorrow. thanks for the links and suggestions

I have the "Killer Light" electric system in my 73.  No vacuum at all to the lights.  They open quickly even when the engine is off and close together in a hurry.  Website is mcspeed.com, great system!

[QUOTE=BRussell] Go to www.corvette-101.com. Click on "vacuum trouble". Follow the troubleshooting steps and you will find the problem. You'll need a small vacuum pump found at Sears, NAPA or Harbor Freight-about 25 bucks. Maybe you have a faulty actuator relay valve on one side. Good Luck. Bob[/QUOTE]

Can this be tested by marking and moving the suspected "good relay to the opposite side and verify if one is bad?
Tuxblacray2006-12-29 20:46:05

Lacking a vacuum pump, you should be able to swap the relays side/side for testing. However, my 68 has only 1 headlight vacuum relay with teed lines, so I haven't tested that theory. If your relays are close enough, maybe you can just swap the lines (left relay to right actuator). Good Luck, Bob

tuxblacray sent you a pm. it might help. i have repaired the problem with some help from here and corvette 101. it turned out to be a relay that made the lights not open right. BR, the only way to check if only 1 of the relays is bad is to have 1 new one there to swap out. my headlights would not open but they would close. after listening to what was said here and the vacumm guide besides the parts i already replaced, i guessed the left relay valve was bad. as i had one on order and it came in yesterday, i did a quick change of hoses to the new one and they work. of course i ordered another one as with my luck if i didn't the other would go too. just switching between the same condition would apply plus what confused me was that if i just hooked up one side at a time they would work separately. again thanks for all the help from everyone.