Headlight vacuum wits end!
Thread Starter
Instructor
Joined: Jun 2024
Posts: 100
Likes: 38
Headlight vacuum wits end! - SOLVED!!!
I know there are MANY topics on this but I have searched endlessly. I’m also a new owner so forgive me 
1978 C3 winking. Passenger side won’t come up. Tested vacuum system with gauge, getting 22HG up and down line all the way to yellow hose at relay. Thought it was relay issue, so have brand new relay. Don’t think the tank has leak as driver side pops up easily. Actuator ‘seems’ ok? That is last thing I can think of that is issue, but I have performed these tests:
- when headlight is pushed up manually and car is running, goes down no problem when I push in switch
-Blow into red line (into back of actuator) and headlamp goes up!
- with car running, have pulled out both green/red hoses and plug, try pushing headlight up/down and get good resistance
- validated 20hg at all inputs at relay/actuator area
What am I missing???
EDIT: Solved! It was the vacuum seal at the relay…completely torn! $9 dollar part replacement and now both headlights pop up super fast!
1978 C3 winking. Passenger side won’t come up. Tested vacuum system with gauge, getting 22HG up and down line all the way to yellow hose at relay. Thought it was relay issue, so have brand new relay. Don’t think the tank has leak as driver side pops up easily. Actuator ‘seems’ ok? That is last thing I can think of that is issue, but I have performed these tests:
- when headlight is pushed up manually and car is running, goes down no problem when I push in switch
-Blow into red line (into back of actuator) and headlamp goes up!
- with car running, have pulled out both green/red hoses and plug, try pushing headlight up/down and get good resistance
- validated 20hg at all inputs at relay/actuator area
What am I missing???
EDIT: Solved! It was the vacuum seal at the relay…completely torn! $9 dollar part replacement and now both headlights pop up super fast!
Last edited by JC 78 Vette; Jun 26, 2024 at 10:44 PM. Reason: Solved!
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
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Try this test. You should have 2 actuator relay valves, one for each actuator. Either run a tee so you can run both actuators off the good side relay valve or swap the relays. It will tell you if it's the relay valve not working which is usually the issue.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,209
Likes: 9,347
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
You can put vacuum straight to it but from what you said the actuator is fine. I've bought new relays that were garbage out of the box....they are cheap Chinese junk
Pro
Joined: Jul 2004
Posts: 713
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From: Waterford CT
Along the same line of thinking as the suggestiong from Rescue Rogers, I would try swapping the "open" lines from the relays to the actuators so the right relay feeds the left headlight and vice versa. If the "wink" switches to the opposite side then it is the relay that is at fault. If the problem remains the same then the relays are good and it is the actuator that is the problem.
Thread Starter
Instructor
Joined: Jun 2024
Posts: 100
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Well, I isolated the good side by capping that vacuum and then moved the hoses on the side I’m having issues with to the relay I know for sure works and it “tries” to open but can’t. It must be actuator or seal in that actuator. Not sure why it passes other test such as when I blow into it it opens or closes when I manually open and shut off lights but oh well.
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
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Cruise-In VIII Veteran
Just yesterday I helped a friend rebuild both his headlight actuators. Badly blown seal on one. But we pulled both and put seal kits in both. His headlights go up and down again!
Hopefully you will get the same results!
Hopefully you will get the same results!
Race Director
Joined: Mar 2017
Posts: 11,947
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From: Virginia
Have you considered either an electric or manual conversion?
Get the electric kit here (Made in USA!):
https://www.ebay.com/itm/155261365162
The manual swap is a bit cheaper, though it may be easier to remove the hood to get all of the vacuum trash out of there.
Get the electric kit here (Made in USA!):
https://www.ebay.com/itm/155261365162
The manual swap is a bit cheaper, though it may be easier to remove the hood to get all of the vacuum trash out of there.
)
Race Director
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Whooo Hooo! Glad you got it! Don't understand how you missed it with a vacuum guage, but you got it!
Instructor
Joined: Dec 2020
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From: Northern VA
