Test the actuators here: http://www.corvette-101.com/vacuum.htm#actuator

Then test thr relays here: http://www.corvette-101.com/vacuum.htm#relay

thank you.

Thanks for taking the time and posting this. Next on my todo list.
Nice workup.

I've posted it before but:
I used my shop vac instead of hand-pumping a mity vac. Works like a charm to pop-up the lights and pop them down(my motor was out of the car at the time)

FINALLY! A comprehensive write-up with diagrams that make sense!

Another vote for making this a sticky.

Thant's 6 votes by my count.

Thanks for the great information, and yes, this should be a sticky!

Will

Thanks again, all, for your kind comments and support.

I intend to maintain the .pdf file that is linked-to in the original post of this thread with updates, corrections, comments, and good stuff from posts on this thread and elsewhere. Click on that link and you'll always get the latest version.

Today's update adds vacuum reservoir tank test methods and tank locations description (from Mid America Motorworks), and a link to Willcox Corvette's “Headlamp Vacuum Hose Schematics 68-82”.

Jerry
78IndyPace

Stuck! Very informative. Thanks for sharing the info!

Thank you!

This should help.

A big Thanks to all. After understanding how the system works, we located the problem (the lack of vacuum) to the headlight pods. Troy is very happy with his vette.

Very well done.

I've just recently replaced all of the vacuum hoses. Now the lights go up and stay up. If I disconnect the hose that goes to the tank, they won't go up.

Anyone have any thoughts?

Given your brief problem description, my guess is your hose connections on your relays are reversed OR the hose connections on your actuators are reversed. Check your connections against Figure 4 in the original posting. When you find and correct your problem, please post your fix on this thread.

Good Luck!
Jerry

Jerry, this is an excellent post. I recently completed the restoration of both of my pop-up headlight assemblies. I studied the mechanical linkages of the originals before I ripped apart and rebuilt them. But when it comes time to re-install them, plus run all of the vacuum lines - knowing how the system works will ensure that everything goes back together properly. You've done much to guarantee that this will happen. Many thanks.

Jerry - Kudos for the great information and glad to see it is now a sticky.

I do have one suggestion - the title of the post should be
"How your headlight vacuum system is supposed to work".

I even put in a vacuum gage in place of my clock so I know when (not if) something is amiss in the vacuum system.

Awesome posts. On to-do list.

Jerry, I recently replaced all my vacuum lines and my headlights work great and so does the wiper door.....that is until about 5-10 minutes later the wiper door will raise. WTF

I have my car in the shop for re-painting but want to fix this as soon as it comes out. I was going to clamp of the vacuum supply to the wiper door and see if I can hold the door down. If this works I would move the clamp further from the door until I find the leak.

Do you think this will work or do you suggest a better method.

All the best and once again thanks.