Headlight door help on 68 Eldorado

[Kim H]

I have a 68 Eldo that the headlight doors do not work. I know I'm probably the only one with this problem. I can get mine to open and close by playing with the vacume lines under the hood but I can not get the switch to open them. I would think the pneumatic part of the switch would be failsafe. It looks like the hoses are hooked up correctly to the switch and I do not hear any air leaks under the dash. Is there a common problem to check for?
Other than buying an impossible to find, expensive, new switch is there any other options out there? How about a remote underhood pneumatic switch from another vehicle?
Hoping someone has some experience with this.

[Loveldos]

Sorry I don't know the answer. You might try asking at the Cadillac-LaSalle Club: http://www.cadillaclasalleclub.org/

[Ranger]

Can you post a picture of the switch? I might have one.

[SwampeastMike]

It's been forever since I worked on vacuum operated headlamp covers, but it was my understanding that vacuum was used to make the entire system as failsafe as possible. If something (or multiple things) failed, the doors would stay open until repair is made with nearly zero chance of them closing unintentionally. Vacuum closes--releasing the vacuum opens to the "normal" state.

If I had to guess, I'd say a piece of debris (perhaps from an old, deteriorating rubber hose) could be clogging an orifice in the headlight switch. In this case, the fix [could] be as simple as careful disassembly and cleaning of the switch.

Also, have you checked for vacuum at the switch with the doors closed and the system under vacuum? Again, it's probably been 30 years, but I seem to recall the one system such system I worked on (in a Plymouth Fury) had two pneumatic connections at the headlight switch and used the same vacuum keeping the doors closed at one connection to operate a three-way pneumatic valve on or near the vacuum canister that "powers" the system via the other line from the switch. With headlights "off", vacuum would build in the canister and system keeping the doors closed. With the headlight switch "on", this same vacuum (NOT engine vacuum) would both relieve the system and prevent a vacuum leak of engine vacuum.

While there are certainly alternative ways to operate such a system, this method would allow for an "emergency open" switch under the hood (which I seem to recall) in the event that the headlamp switch portion fails while keeping the entire system quite fail safe and minimizing the possibility of a constant leak in engine vacuum in the event of a problem with the headlamp switch.

Believe it or not, it was once suspected that pneumatic computer systems using a similar control system (it is quite like a transistor) would be built the assumption being that pneumatic systems would not only be smaller, but less costly to build, power and maintain than "pure" electronics. Meanwhile, the pure electronics theorists said flat, thin televisions that you could "hang on the wall like a picture" and video telephones would be common in the 1970s...

[CadCliff]

I am also working on one also...1967.
This was mostly an all original untouched car.
After replacing all the vacuum lines, check valves and headlight actuators (68 Camaro RS with minor modification), I am still having issues.
My car is a twilight sentinel car.
I even tried to run the hoses to act as if I bypassed the sentinel part.
I checked the headlight switch according to the manual and it seemed like it was fine....
Then we came back to the headlight switch after we changed the vacuum lines around to bypass the sentinel part, this is when we noticed a vacuum leak in the headlight switch.

After an hour of trying to get the headlight switch out and taken apart.....
the "slider/vacuum" part of the switch had a leak. Took that apart and realized that the slider part was basically "worn out".

This is very similar to the 59-60 Cad Tri Power center carb vacuum switch that operates the other 2 carbs.

Basically we took the slider out and turned it upside down so that the worn part was at the other end of the switch where it did not matter.

I am hoping to put it back together tomorrow.

ALSO.... on the cars with the Sentinel, there is a vacuum solenoid on the radiator core support next to the air tank....this can also be a problem.

I took that apart and noticed there is an adjustment screw. ALSO, I noticed that the factory "sealant" around the edges of this switch was peeling off, possibly allowing air to escape.

Way toooooooo many issues to figure out.

I spoke with a friend who worked at a dealer starting in 1969 and he worked on many of these and he remembers using some sort of AC slider vacuum switch and installing under the dash to by pass the vacuum part of the headlight switch. I guess even then, the headlight switches were very pricey.

Hope that helps or ????
I might still need a new switch or I am trying to locate some sort of "manual" switch to put under the dash.

Cliff

[Kim H]

Thanks for the input
I am going to read these post slowly again to see if something pans out.
I do not have the Sentinel and my doors stay down not open when not hooked up.
I take it getting the switch out is a PITA.

Thanks