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1968 Eldorado "eyelid open while asleep"

Started by mikanystrom, December 06, 2015, 01:53:59 PM

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mikanystrom

I have a question on an arcane detail.  I think only 23,000 of these cars were made in the first place so who knows if anyone still remembers...

This question pertains specifically to the 1968 Eldorado.  Not the '67. 

I fixed my headlight door actuators using a procedure I found somewhere on the Internet.  I bought Camaro actuators (reproduction), cut off the ends of the actuators to make them the same length as the originals, then ground down the rods a bit and finally threaded them with thread-cutting dies, so I could put the Cadillac yokes on (which obviously attach differently from the Chevy yokes..)

Hooked up all the darn vacuum by the book as far as I can tell, new silicone hoses for the most part.  And the system works.  My car originally had Twilight Sentinel so it goes via a solenoid valve, not direct from the light switch.

I just have one complaint.  When the car "goes to sleep" (i.e., I turn off the lights and engine and walk away), the doors shut perfectly.  Then some minutes later (I've never had the patience to watch exactly how much later), the left headlamp door (and only the left), "winks" open a bit (about an inch or so).  It looks like the car is having a bad dream or something!

My question is: is this normal?  I thought I would have to debug the issue and fix it somehow, but the following link suggests it's actually normal for the car and is "an unfortunate side effect of a safety improvement" (said safety improvement being that in 1968 the system was redesigned so that a failure of the solenoid valve, specifically, would result in the doors sticking open, not shut, whereas on the 67s you might have to manually open the doors to get light on the road)....

http://wikicadillac.org/tiki-index.php?page=Headlamp+Doors
1970 De Ville Convertible
1993 Fleetwood Brougham
1970 Series 75 Formal Sedan
1968 Eldorado "Purple Sister"
------------------------------------------------
1976 Pontiac Firebird Trans Am 455 4-spd
1999 Camaro SS Convertible 6-spd
1999 Honda CBR 1100XX :-)

Glen

#1
In a sense this is normal, my 68 ELDO does that also.  The cure is to fix the check valve between the manifold and the storage tank.  Also fix any other vacuum leaks.  As long as the vacuum is there the doors will stay closed.   When new the vacuum would hold the doors closed when the car is not driven for a couple of weeks as I recall. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

Viator Trudeau

RE: '68 eldo,  Apx.12yrs.ago my head lights would close after the engine was stopped.   The piston seals leaked and W/ no vacuum available gravity would close them,easily moved because the "O " ring seals were loose and leaked.  I ground the crimped end caps off and put a night line backer ( one turn ) behind the
o rings.  There is enough friction now between  the
o ring and cyl. wall, it takes a lot of vacuum to move them, they won't move by themselves.  There is an  o ring seal where the cyl. rod goes thru the top of the cyl.and can be easily replaced with the top off.  Use wire brads thru the top edge of cyl to index it and keep it in place and use a bead of J-B weld to seal where you ground off the top clinch of the cyl.   I sent out a sketch some time ago, if I can find the original I will send it out.
V. Trudeau

Glen

Viator,  I’ve been down that road too, I even made my own piston seals.  The issue Mika is referring to is that the last gasp of vacuum in the system is used to open the door a little.  This is found only in the 68 Eldo with Twilight Sentinel.  This does not happen with the 67 Eldo or the 68 without Twilight Sentinel. 
If you are standing nearby when it happens you can actually hear the car gasp. 
I have not had a lot of problems with the actuator leaking but the check valve is shot and the storage tank leaks down in a few minutes.  Anybody know where I can get a replacement check valve? 
Also if anybody has improvement for that article let me know I would like it to be better. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

mikanystrom

Thanks for the input, guys!

Here is what I am using for the check valve:


NEW VW Audi Vacuum Check Valve 5/16 or 8mm Plastic 058 905 291K

Bought it off eBay for $7.80 delivered.
1970 De Ville Convertible
1993 Fleetwood Brougham
1970 Series 75 Formal Sedan
1968 Eldorado "Purple Sister"
------------------------------------------------
1976 Pontiac Firebird Trans Am 455 4-spd
1999 Camaro SS Convertible 6-spd
1999 Honda CBR 1100XX :-)

Lars Kneller 8246

I think the problem may also be with the vacuum storage tank and how well it seals, and the headlamp switch too. My 68's doors will stay closed for months if I don't use the headlamps, but whenever I do, it takes several drives and playing around with the headlamp switch before they'll stay closed. The door locks in the same car, however, only work for a few minutes after the car is turned off. I've never looked into that problem. My 66 has a power trunk (that I added) and it also holds vacuum for months. My wife has a 69 Thunderbird with hidden headlamps and I've never been able to get them to stay closed for very long. I rigged up two short pieces of broom handle with rubber caps on both ends, and just wedge the doors shut. It only creates an issue when it's dark out, and I forget about them and wonder why the headlamps won't turn on!