I'm putting my '71 back together after swapping engines and now trying to figure the headlights out... what is supposed to make these bad boys pop up? after they are manually raised, I shoot air in the vacuum lines, they drop just fine, but for the life of me dont know what mechanism raises them.

thanks,
Timbo2

 

Your supposed to use vacuum. There are two ports on the cannisters. One side raises the other side puts them down. Try the other port on the other side of the cannister. Just don't use to much air pressure. They are designed to work at around 10 to 15 inches of vacuum. If you go shooting 90 psi of air in them you can rupture the diaphram.

 

The same mech that closes them, raises them. It just depends what side of the canister gets vacuum.



Or... what he said!

[Modified by lbell101, 7:40 PM 12/11/2003]


[Modified by lbell101, 7:40 PM 12/11/2003]

 

ok, i just took the line off othe "relay valve assembly" and blew on it and the headlight came up fine.... took the other line off and blew and it went down fine, however when I replace the lines, then blow in the main line running to I suppose the vacuum source, I hear air escaping from the relay valve assembly.. is there a way to see if these are bad? what is the usual vacuum source ? on the previous engine this line was hooked to the bottom front of carb.

Tim

 

What you did wrong is blow. The system works on vacuum, or suction. Apply a vacuum to the main hose and the lights should go up.

Each actuator has 2 ports. Sucking on one raises the lights, sucing on the other lowers them. THere's a separate part of the system that directs the suction to the proper side of the actuator to raise or lower the lights.

Let me dig for a description of the system that I previously wrote.

 

aahhhhh...I see. yep.. I sucked on one of the lines and sho enuf... the right headlight popped right up. the left one has the little rubber boot on the shaft at the bottom of the actuator assembly that is tore lose. Is the repairable, or am I gonna have to replace the actuator assembly? also, where does the vacuum line get attached? on the intake or the carb?

thanks so much.
Tim

 

Couldn't find my prior post, so I re-wrote the basics:

Ok, the system works like this:

Vacuum is generated and supplied by the intake manifold/carburetor.

There's a main hose that runs into a splitter (check valve). There are 2 hoses coming out of the check valve, one big, one small. Let's follow the big one first:

The big hose runs into the vacuum canister that's mounted behind the left wheelwell, next to the brake master cylinder. Hoses come out of the canister and run to 2 places. The front hose runs along the left side of the engine compartment and up to the nose of the car. It enters a relay valve. The relay valve has one big hose going in and 2 coming out. Inside the valve there's a spring-loaded mechanism that routes the vacuum from the tube going in (from the vacuum canister) and directs it out one of the other 2 hoses. One of those hoses goes to the front of the actuator can on the headlight, and the other goes to the rear.

So what makes the relay valve move? That's the other side of the system.

From the check valve, the small tube runs inside the car. It splits in 2 with one side dedicated to the wiper door, and the other for the headlights. We'll stick with the headlights.

The hose runs to the override valve under the dash, and to the headlight switch, and then up to the small connection on the relay valve up by the headlights. The way these switches work is that with everything off (override off and lights off) there is vacuum that goes up to the relay valve. This vacuum pulls against the spring in the relay valve and moves the valve so that the big vacuum hose's vacuum is directed to the "close" side of the headlight actuator.

When you turn on the lights or pull the override ****, you break that vacuum so it no longer goes to the front of the car. So the hose going to that small valve now is open to the atmosphere (i.e. has no vacuum in it). With no vacuum, there's nothing to pull against the spring in the relay valve, so the valve moves to the position where it sends vacuum to the "open" side of the headlight actuator.

The wiper door side of the system is identical in principal with a couple of extra bits in there to make sure that the wipers don'tt try to wipe before the door is open and so the door doesn't close while the wipers are running.

Hopefully that makes sense.

:cheers:
Dave





[Modified by ddecart, 9:05 PM 12/11/2003]

 

I'll look this over and see what I can figure out. thanks so much!


Timbo2
'71 project

 

Yup. They sell boot repair kit things.

And the hose can be hooked up to either the carb or the intake manifold. I think the factory connection was to the carb

 

[QUOTE]
Yup. They sell boot repair kit things.

the boot appears to be intact, maybe just pulled out ...how does one go about putting in back in what appears to be a little groove around where the shaft goes in? or is that even possible?

Tim

 

Tim,

Here are a couple of links to articles at corvettefaq.com which deal with headlight actuator seal and vacumm relay repairs

http://www.corvettefaq.com/redir.asp?site=361
http://www.corvettefaq.com/redir.asp?site=554

Mike