headlights,,,
Thread Starter
Le Mans Master
Joined: Jul 2003
Posts: 7,501
Likes: 1
From: Maine
headlights,,,
when I shut my car off the headlights start up and go back down,,,, they don't move far,, maybe an inch,, I wouldn't have even seen it but I heard it the other day,, any ideas?
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Yes,
the vacuum is bleeding off too fast...thus allowing the actuator control valve(s) to change their position...which thus moves the plunger valve inside the actuator control valve to the OPEN position...which will raise the headlights and then allow them to go down due to the vacuum bleeding off.
Several areas or components can be causing this.
Like mentioned...if they work...do not worry about it unless you just can not handle the issue.
DUB
the vacuum is bleeding off too fast...thus allowing the actuator control valve(s) to change their position...which thus moves the plunger valve inside the actuator control valve to the OPEN position...which will raise the headlights and then allow them to go down due to the vacuum bleeding off.
Several areas or components can be causing this.
Like mentioned...if they work...do not worry about it unless you just can not handle the issue.
DUB
Racer
Joined: Nov 2011
Posts: 401
Likes: 40
Yes,
the vacuum is bleeding off too fast...thus allowing the actuator control valve(s) to change their position...which thus moves the plunger valve inside the actuator control valve to the OPEN position...which will raise the headlights and then allow them to go down due to the vacuum bleeding off.
Several areas or components can be causing this.
Like mentioned...if they work...do not worry about it unless you just can not handle the issue.
DUB
the vacuum is bleeding off too fast...thus allowing the actuator control valve(s) to change their position...which thus moves the plunger valve inside the actuator control valve to the OPEN position...which will raise the headlights and then allow them to go down due to the vacuum bleeding off.
Several areas or components can be causing this.
Like mentioned...if they work...do not worry about it unless you just can not handle the issue.
DUB
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Yes..
With a defective check valve when you shut off the car, you lose vacuum on the small hose side momentarily until you also lose it on the large hose side... This is why it pops up, then down.
As dub stated, it could also be something else leaking vacuum that causes this. But the twitch is caused by losing vacuum on the small hose first, then the large hose.
With a defective check valve when you shut off the car, you lose vacuum on the small hose side momentarily until you also lose it on the large hose side... This is why it pops up, then down.
As dub stated, it could also be something else leaking vacuum that causes this. But the twitch is caused by losing vacuum on the small hose first, then the large hose.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Years ago when I got it, in '95, my '72 had a vac canister under the left fender, looked like a small steel gas tank, it had stress cracks in it, I took it outta the circuit, so the lights/door did not operate with engine off....so what....
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Removing vacuum storage has a down-side.
The steel vacuum storage tank...regardless on year and or design that has vacuum operated headlights, wiper door, and HVAC. is NOT there so "things" will work without the engine running. The storage tank ...even the 1984-1996 Corvette vacuum storage tank..is there so when vacuum supply values change when the engine is running and RPM values change...vacuum operated components do not change position due to the change in vacuum values to these components.
So if you are going down the street and you have your defroster on...and due to throttle angles...the vacuum values change...your defroster air stops and it changes to the floor and you loose defroster...the vacuum storage capabilities are lost and you are now making your components rely on what ever the engine provides in vacuum.
DUB
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