Topic: Vacuum controls: headlight doors close but don't reopen on 68E
in Forum: C3 Electrical
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Australia
Joined: 10/27/2010
Posts: 54
Vette(s): Second-month production Shark, this 1968E was built up by original owner into 1969 ZR1 (L88 body with LT1 engine) for Club Racing. Body styling is from Maglioli's 1968 L88 "Le Mans" racer
Since the headlight vacuum controls are related to electrical, I guessed a query belongs here? Car is a 68E.
I do have the vacuum troubleshooting manual, and the 68 assy manual; and between the pair of them I'd have reckoned I have all the bits connected correctly.
But: with the headlight doors open, starting the car closes the doors briskly, and the headlights turn on and off with the switch but the doors don't re-open.
Neither override switch has any effect on the doors (even when I re-traced all and it appeared I had the rubber plug-ins at the override switches reversed).
Anyone clever enough to know what the problem is?
Thanks so much.
1968E (2nd month production) convertible first registered California 1967 and a retired SCCA race car. It is still race prepped and built up as a '69 ZR1 (announced '69 but not built until '70); i.e., the L88 car with LT1 motor.
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Arrrrgh! Not another vacuum problem!!!
So the doors slam shut when you start the engine. How do they get up/open in the first place? Are you manually opening them? If so, then they should close when the engine is started(unless you have the over-ride knob pulled down, or the headlight switch on), so the "down" part is working.
I don't know which troubleshooting guide you have, but I have a couple of different ones, with diagrams, and such. I'd be happy to e-mail them if ya want. If all of the hoses are correctly positioned, and all of the vacuum relays are working, and the actuators are in good shape, then they should work correctly...but of course, they never do. I know of at least one vacuum diagram that has the hoses in the wrong location, too...
I can only suggest that you check and make sure the check valve is working, and your vacuum tank isn't leaking...
So the doors slam shut when you start the engine. How do they get up/open in the first place? Are you manually opening them? If so, then they should close when the engine is started(unless you have the over-ride knob pulled down, or the headlight switch on), so the "down" part is working.
I don't know which troubleshooting guide you have, but I have a couple of different ones, with diagrams, and such. I'd be happy to e-mail them if ya want. If all of the hoses are correctly positioned, and all of the vacuum relays are working, and the actuators are in good shape, then they should work correctly...but of course, they never do. I know of at least one vacuum diagram that has the hoses in the wrong location, too...
I can only suggest that you check and make sure the check valve is working, and your vacuum tank isn't leaking...
Joel Adams
C3VR Lifetime Member #56 
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Former Member
Send PM
Australia
Joined: 10/27/2010
Posts: 54
Vette(s): Second-month production Shark, this 1968E was built up by original owner into 1969 ZR1 (L88 body with LT1 engine) for Club Racing. Body styling is from Maglioli's 1968 L88 "Le Mans" racer
Joel's sent along some diagrams; thanks, Joel! The diagram titled 'simplified' indicated that I had the hoses at the headlight switch reversed (from what is shown on Corvette Central's diagram for the 68E) but reversing them made no difference. The 68E uses a single vacuum relay for both headlights, vs the pair used on later models. So the typical diagram for 69 and later has to be 'interpreted'.
|UPDATED|12/28/2011 6:45:44 PM (AZT)|/UPDATED|
Later an accidental high rpm start broke free the wiper door when using the override valve; it now opens and closes freely even at low idle with the override valve.
And if I manually open the headlight doors, that override valve will close them (but not reopen them).
Easy to understand why kits offering to replace 'those troublesome vacuum headlights' have a market.
I'll eventually get around to acquiring a vacuum test pump on eBay, locally they're very expensive; and use Joel's test regimen on each and every component.
|UPDATED|12/28/2011 6:45:44 PM (AZT)|/UPDATED|
1968E (2nd month production) convertible first registered California 1967 and a retired SCCA race car. It is still race prepped and built up as a '69 ZR1 (announced '69 but not built until '70); i.e., the L88 car with LT1 motor.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
My best guess would be that the headlight door relay is not functioning properly, since both doors will not open.
A hand-held vacuum pump will work, as will an air conditioning evacuation pump, if you can find one. I have both, but...they're easy to come by here.
Here's a Mityvac on ebay now for $5!
http://www.ebay.com/itm/Mighty-Vac-vacuum-pump-/160704722476?pt=Motors_Automotive_Tools&vxp=mtr&hash=item256abf762c
A hand-held vacuum pump will work, as will an air conditioning evacuation pump, if you can find one. I have both, but...they're easy to come by here.
Here's a Mityvac on ebay now for $5!
http://www.ebay.com/itm/Mighty-Vac-vacuum-pump-/160704722476?pt=Motors_Automotive_Tools&vxp=mtr&hash=item256abf762c
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
in Forum: C3 Electrical
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