We spent considerable time today attempting to smoke out the problem. I have 20+ years in the high-vacuum industry - this oughta be a piece of cake... Here's what we have:
· With headlights ‘ON’, applying smoke at the T in the control line between the headlights we had smoke billowing out of the headlight switch area.

· With headlights ‘OFF’, applying smoke at the same T, no smoke at switch

· Engine running, VAC gauge connected at T in headlight control line the wiper door closed. ~ 10” VAC at the headlight control line T (I previously I measured 12” on the vac advance line which jives with Duke W and other sources)

· Right headlight needs more vacuum than the left to close (both closed when vac applied to control line with hand vac pump) with the engine running.

· With wipers ‘OFF’ (but wiper door was open)there was smoke from under the wiper door on the right side. I regret I didn’t note if smoke was to ‘white’ line or ‘yellow’ line.



History

· Problem first showed as headlights going up shortly after starting the car. At first they responded to manipulating the manual override. They also responded to pulling the headlight switch, and then shutting them off.

· Later it required a fair vacuum, (closed throttle, better than 2K rpm) to get them to close.

· At night they would close when headlights shut off. Even if engine shut off first. The last time only the left headlight closed. Nothing since would convince them, or the wiper door to close.

· Somewhere along the line the wiper door got into the act.
I've not been able to determine where the vac is vented when headlights are turned on. I'm guessing at the switch, but I can't imagine that stays 'open' causing a continuous leak.

Other:
Car starts fine
Car idles @ ~900rpm

So Internet friends, I throw myself upon your expertise...

Thank you!

 

Hey Ed.....you have a vacuum leak. All done. Hows everything else going?

 

So I would bet that you are leaking at one of the actuator relays...I believe you have 2. IF you have an electric vacuum pump you can run an air hose to your engine vacuum source hose and pull a vacuum on the whole system. WIth the pump outside the garage you should be able to hear where the leak is. When my headlight switch started leaking it usually is catostrophiic not a slow and gradually increasing leak. When the actuator relays go they o ring usually falls apart and it gets steadily worse. It will give you the symptoms you describe.

If you remove the tee at the headlights and just use one actuator relay and one headlight you can narrow it down to see if its one side or the other

 

I might have an old switch out in the garage, I can look for it tomorrow, I can tell you where the vent is but I dont think that its your issue.....but it could be as The newer switches dont last long

 

Indeed, a leak somewhere.

When we evacuated from T forward, lights went up, and vacuum reading stayed constant. Anything audible would have been masked by the idiotic road construction project. Same when we vacated back from the T, and the wiper door went down.

Oh, and I have a book for you! Bummer it was supposed to be autographed. When I read some of his exploits I thought, 'Rescue Rogers'! Thank you!

 

Are you just testing the work side of the vacuum system. The leak to me sounded like the black and white line was leaking or was near the leak on the control side. Can you work backwards from the tee to the switch to see if your vacuum is constant. You just have the manual vent then the switch to test.....I would try to test at the tee on the tach to pull vacuum through the switch to test it. ITs a lot easier to get too than the switch itself.

 

Tested B&W with engine running.

 

the switches under the dash are not supposed to vent vacuum. vacuum holds headlights down. lack of vac causes them to go up. when you turn on headlights or bypass switch you stop flow of vac to headlight relays. it is supposed to just seal. venting vac when lights on would be the equivalent of turning off a light switch and have the electricity short to ground instead of travelling to the bulb. also kind of backward-thinking cuz it is not flow of vacuum. the air is sucked out of the line until there is none left. what is left is vacuum. you know this but many do not.
you know, it may be designed to vent the load side. you have vacuum holding the headlight relay closed. you close the valve that connects the headlight relay to engine vacuum. if you have no vacuum leak, the vacuum in the relay will not leave. the headlights will stay down. so i think the switches are designed to shut off from the switch to the intake manifold, but vent from the switch to the relay. so if blowing smoke on the relay side, it is supposed to come out under the dash.

 

the headlights go up after starting the car cuz it takes more engine vac to pull relay closed than it does to raise the headlights. the relay is a small one way vactuator. (new word!) vacuum pulls relay to close lights. spring pulls the relay the other way to open lights. i have found i can suck one headlight open or closed with lung-powered vacuum pump. which is only about 2 psi pressure diff. no, i am not advocating keeping a hooker in the car in case you lose headlight vacuum. the wife won't believe your reason...