Headlamp vacuum system question
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Pro
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Headlamp vacuum system question
Yesterday I set to replacing the broken headlamp adjusters and tried to get the lamps to stay up, no dice.
I fire it up turn on the lamps, they come up and then pull the override pin… they go down with the lamps lit.
push it back up and they come up.
turn the lamps off and they go down. Pull the pin down, nothing. Turn the lamps on and they stay down, push the pin up and the lamps come up.
turn off the car with the lamps on and up and in a moment they go down.
everything I’ve tried according to the manual and what I’ve seen on YouTube, every configuration I can think of has failed to leave the lamps up when the car is shut off.
I’m inclined to think the headlight actuators are either bleeding vacuum (both?) or a line is bleeding vacuum (?)
Anyone else run into this?
I fire it up turn on the lamps, they come up and then pull the override pin… they go down with the lamps lit.
push it back up and they come up.
turn the lamps off and they go down. Pull the pin down, nothing. Turn the lamps on and they stay down, push the pin up and the lamps come up.
turn off the car with the lamps on and up and in a moment they go down.
everything I’ve tried according to the manual and what I’ve seen on YouTube, every configuration I can think of has failed to leave the lamps up when the car is shut off.
I’m inclined to think the headlight actuators are either bleeding vacuum (both?) or a line is bleeding vacuum (?)
Anyone else run into this?
Is my vette stock?? HAHA
Joined: Oct 2015
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2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
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They are supposed to fail up. When you operate the override it is supposed to bleed the vacuum at the top of the actuator relay to open them. Seeing it Works when you turn them on and not with the override would indicate a leak in the relay or line on the control side
Maybe the hoses on the override are reversed.
You can push the lamps up with the motor off by pushing on the hinge joint. It takes a few times to find the sweet spot
Maybe the hoses on the override are reversed.
You can push the lamps up with the motor off by pushing on the hinge joint. It takes a few times to find the sweet spot
Racer
Joined: Oct 2018
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From: England
It sounds to me as if your vacuum system is working correctly. My guess would be that the headlights don't stay up without the car running because you don't have the mechanism adjusted quite right. When the headlights go up the mechanism is supposed snap into an over centre position which holds it in place until vacuum is applied to pull them back down. I found this thread very useful when setting mine up.
https://www.corvetteforum.com/forums...alignment.html
https://www.corvetteforum.com/forums...alignment.html
Thread Starter
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Joined: Mar 2022
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They are supposed to fail up. When you operate the override it is supposed to bleed the vacuum at the top of the actuator relay to open them. Seeing it Works when you turn them on and not with the override would indicate a leak in the relay or line on the control side
Maybe the hoses on the override are reversed.
You can push the lamps up with the motor off by pushing on the hinge joint. It takes a few times to find the sweet spot
Maybe the hoses on the override are reversed.
You can push the lamps up with the motor off by pushing on the hinge joint. It takes a few times to find the sweet spot
I did end up gently raising the lamps propping them up to change the adjusters. I also wet sanded the bezels and cleaned all the paint overspray off the bright work and bulbs.
I figured to save the wipers and vacuum hoses for a winter project.
You may very well be right about the hoses being reversed on the relay.
Here’s what the lamps and bezels were like before and now…
It looks like rust but it’s red primer and green paint overspray all over the rings and glass lamps. Blue tape is your friend for projects like this preventing scratches. Use it like you have stock in the company
The bezels had mismatched rusted screws which were replaced with stainless. While they were British green it’s not like I can go get that from autozone so I went with flat black, Technically incorrect but gave a clean look. In that the car looks black in low light and after dark I don’t think it’ll look bad if anyone notices at all.
That black spot on the drivers side low beam is inside the glass. Though it’s lit it’s on its way out.
Last edited by Lt.Mike; Aug 4, 2022 at 02:26 PM.
Thread Starter
Pro
Joined: Mar 2022
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It sounds to me as if your vacuum system is working correctly. My guess would be that the headlights don't stay up without the car running because you don't have the mechanism adjusted quite right. When the headlights go up the mechanism is supposed snap into an over centre position which holds it in place until vacuum is applied to pull them back down. I found this thread very useful when setting mine up.
https://www.corvetteforum.com/forums...alignment.html
https://www.corvetteforum.com/forums...alignment.html
That’s a very good tutorial and I’ll definitely use it.
Race Director
Joined: Jul 2015
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From: SW Florida.
one thing. be careful pulling the lamps up. avoid the switch that tells the car the lights are up. it will break right off in your hand if you pull on it. the headlight switch and the override just stop flow of vacuum to the relay. can't be hooked up backwards.vacuum to relay holds the lights down. lack of vacuum and the lights "are supposed" to go up. there is a one-way valve that leaks and lets vac bleed off. they fail up. IF there is vacuum to the big hoses on the relays. no vac there and they fail right wherever they are. people step on the gas and the lights go up the one-way valve is shot. sounds like you have a vacuum leak. maybe a T fitting and a vacuum gauge to see how fast it drops. the tank itself is a repairable fail point. you can get a big T fitting and bypass the tank completely to see if they behave better, but only when rinning. of course you can really live without headlights opening or closing with engine off. at least for the time being.
Last edited by derekderek; Aug 4, 2022 at 02:43 PM.
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)
2019 C3 of Year Winner (performance mods)
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The key is they go down with the engine on and the override pulled down....no vacuum they would go up, so there is a vaccum signal pulling them down,
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Le Mans Master
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2022 C3 of the Year Finalist - Modified
The headlights have an "over-center" mechanism,....driven by springs, that keep them up or down, based on vacuum. Without vacuum,.....they can be pushed up, or down, by pressing the right part of the mechanism from underneath. Vacuum is really not even required.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,108
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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)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
With your motor off, when you lift the headlights manually and they shut, quickly pull the vacuum hose that goes to the center of the 3 nipples on your actuator relay. Do you hear vacuum noise. If you fo then something is connected wrong. If you do not you may not be pushing them up far enough to go over center. The hinge acts like a double jointed knuckle. If it doesnt then they need an adjustment. They shouldnt since the headlights normally work but it may be the vacuum is strong enough to keep them open.
To shut them you need to push the joinr and then allow them to slowly shut on there own
To shut them you need to push the joinr and then allow them to slowly shut on there own