Hi Guys,

My search feature does not work so this may have been addressed before. I drove my 69 today and played with the headlights. They came up slower that usual and won't go back down. I drove around for a while hoping the vacuum would catch up. No such luck. The lines have been redone at least once. No obvious broken or loose hoses... Lower dash switch won't close them either.

 

Pull down on this part to close.
Guide:
https://www.corvette-101.com/vacuum.htm

 

Does your heater / air conditioning system vacuum operated doors work? If you don’t get any movement, ie, defrost door, then start looking at the main vacuum hose behind the carburetor. The hose splits and there is a hose that goes to each system.

 

Maybe it’s not really stuck up. Maybe it’s just shy and/or socially awkward.

sorry

As mentioned above. I think the hose behind the radiator is what fixed my son’s headlight issues.

 

Pulling them down manually is the short term fix. See above post as to where to pull. Lay on your back looking up from underneath. Flip the linkage and down they come. Then start trouble shooting the vacuum system. Actually a very simple basic system.

 

Failsafe on the headlights is up.

That is, vacuum must be present to pull them down. One leak, one cracked hose, one hose that's fallen off its nipple and yer headlights stay up.

Start by going around in the engine bay checking the hoses from the manifold, cannister, TO the headlight relays & actuators in front of the radiator.

Vacuum is used both to POWER the headlight actuators and also to CONTROL the vacuum relays.

So you can lose power OR lose control and have your headlights stay up.

WITH control vacuum, the headlight actuators pull the headlights down. IF they have "power"

WITHOUT power vacuum, the headlights stay wherever they were when it was lost. Bistable.

Losing control is all (90%) behind the dash. The headlight switch, the emergency override switch (ditto for wiper door),

Hose fell off my headlight switch recently, leaving me headlights up all the time. I had knocked it off working on the AC duct but managed
to get it back on without completely pulling the speedo/tach cluster - loosen the cluster, long needlenose, coming in from the door side.

Did you lose POWER vacuum, vacuum from the manifold, to the one-way, through the canister, to the headlight relays?

Or did you lose CONTROL vacuum --- vacuum from inside the cockpit CONTROLLING the headlight relays.

See if you can get the headlights to pull down by putting a hose on the headlight relays (control input) and using a Mighty Might hand vacuum pump. (Motor running)

If you can, then you know you lost yer CONTROL input.

Headlights stuck up:

9/10 it's an older vacuum hose, hardened, cracked, leaking air around the nipple it's stabbed onto. Or fallen off of.

9/10 it's ONE SINGLE hose that's causing your problems. Don't go and disassemble the whole system. LOCATE that one hose.

1/10... failed headlight actuator or relay

Since this is a recent failure, it's most likely NOT a control hose stabbed on the wrong nipple like when guys been messin' with 'em.


Also:

>Faster C3 headlights in 15 minutes

Open the hood, get out your tubing cutter, cut 1/2" all off all 11 of the hardened, cracked headlight relay/actuator hose ends up there in front of the radiator

One at a time, PLEASE!

You can do 9 of them from the top... two of 'em require laying on the ground.

Lube 'em up with (NAPA) Silglyde and slide 'em back onto the actuator nipples, solenoid nipples, and T's.

Will make a noticeable difference in headlight speed.

Next do the connections on your vacuum canister, etc.

Also:

Batman, I can say confidently your problem is with one of this select group of vacuum lines:

 

It will definatley give me something to do... Thanks guys.

 

So thank you much for the info. I managed to manually close the headlights. Guess what happens after the cars been started for about 30 seconds. Yes, they both come back up. Under hood hoses all look good. I'll take a look at the dash lines next.

 

Here's a slightly clearer explanation of the same thing: https://www.reddit.com/r/Corvette/co...r_luckyatlast/

 

I gave up on the vacuum head lights and wiper door and use the electric set up and never looked back .