headlight door opens by itself
Thread Starter
Pro
Joined: Jul 2010
Posts: 561
Likes: 279
From: Louisville KY
headlight door opens by itself
Why would my right headlight door open by itself when driving? Its happened the past couple of times Ive taken it out..... I'll turn off car...get out and notice right headlight door is up....then I start engine and turn on/then off and the door shuts...Only thing I have changed on the car is that I blocked off EGR valve mount. I figured that would give me for vacuum. The headlights open seconds apart and close seconds apart...they have done that since I've owned the car...
Last edited by Jetglow; Aug 22, 2018 at 06:43 PM.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,033
Likes: 9,155
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
maybe a vcuum leak for that side
Le Mans Master
Joined: Aug 2006
Posts: 7,410
Likes: 1,547
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
You have a vacuum leak.
Start at the manifold and check all the hoses and parts as you go.
http://www.corvette-101.com/vacuum.htm
Start at the manifold and check all the hoses and parts as you go.
http://www.corvette-101.com/vacuum.htm
Just another Corvette guy
Joined: Feb 1999
Posts: 8,518
Likes: 3,863
From: Palm Springs, CA.
You have a vacuum leak.
Start at the manifold and check all the hoses and parts as you go.
http://www.corvette-101.com/vacuum.htm
Start at the manifold and check all the hoses and parts as you go.
http://www.corvette-101.com/vacuum.htm
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
The headlamp door will open or close depending on which side of the actuator gets MORE vacuum. The two doors will open and close nearly simultaneously if all the system parts are leak free. I think your right-side vacuum relay is the likely issue. But there are other faults that could cause very similar results. If you have a spray can of white lithium grease, pull the center (vacuum feed) hose on the right-side vacuum relay and spray a puff of that stuff into the relay. That will 'lube' the seals on that shuttle valve and reduce any leakage you might normally be experiencing. If the door operation does not change in any way, the relay is not likely to be the problem. If that improves performance or keeps the door from opening on its own, replacing that relay may just solve your issue. If so, I would suggest that you change both relays, as the other one may not be that far behind on failing.
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Safety Car
Joined: Sep 2013
Posts: 4,355
Likes: 2,631
From: Draper Utah
If your existing relay is not leaking don't replace it as the Chinese repop relays are pretty much junk. I went through 5 repop relays and they would only last a couple of months. I finally had a forum member rebuild my factory relays and they have lasted. I did finally find a source for American made relays that are good, I believe the doctor carries them.
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
Here's an extraordinarily helpful forum post.
While you likely do have leaks, a headlamp that "winks" under acceleration is commonly caused by a defective check valve. It's purpose to keep the system under constant vacuum regardless of temporary changes in manifold vacuum. They're very easy to check by mouth. Connect a line to one of the connectors on the side with two. Cover the other on the side with two with your finger. Leave the connection on the other side open. Try to suck through the tube. If you can, the valve is bad. If you have a hand vacuum pump do the same--it should hold vacuum for hours and hours.
While you likely do have leaks, a headlamp that "winks" under acceleration is commonly caused by a defective check valve. It's purpose to keep the system under constant vacuum regardless of temporary changes in manifold vacuum. They're very easy to check by mouth. Connect a line to one of the connectors on the side with two. Cover the other on the side with two with your finger. Leave the connection on the other side open. Try to suck through the tube. If you can, the valve is bad. If you have a hand vacuum pump do the same--it should hold vacuum for hours and hours.
