daniel77350

I have a question about my vacuum setup on my 77 for the headlights. My lights have been stuck in the up position for a while now and Im tired of people looking at the car and saying "headlights stuck eh?" I cannot convince them I just want my lights on durring the day, so I figured now is a good time to repair my system. I fallowed every hose to ever end(went so far as to drop the lower dash to fallow the underdash hoses). Here is what I have:

Goes from light switch to vacuum override to both actuator relays, from the relays it goes to the front and back of the actuator and to the air canister reserve thing, then from there back to the light switch. the line from the override to the actuator relays is y'ed off and goes to the manifold. Here is the crazy part. The reserve canister thing is in the front of the car below the actuators and is a big long tube, it looks like a structual thing in case i get into an accident. Thats what I thought it was at first, because all my diagrams says the canister is in the drivers side fender, but when I looked closer, all my lines go into it that normall go into the reserve canister, which led me to believe that that bar surved two purposes(1 in case of an accident, and 2 as my reserve). Does this seem right? if so, all lines are intact and are visually in good shape( dunno about the insides).

when I put the override switch in the up position, and pull out the lights my lights come on and I get what sounds like a "deep breath", where someone is breathing in deeply. when I close the light switch I get a hissing noise. These noises come from the light switch. When the light switch is closed and I open the override nothing happens(the lights are already up), but when I close the override I get the hissing noise again. To test it, I closed the override and opened the light switch, then pinched the line w/the blue stripe right as it exited the switch. When I closed the light my hissing went away, but when I let go of the line, it hissed. This happened on the other line as well. What would you conclude to be the problem? did I overlook a line or two that is in bad shape, is my system configured incorrectly? Does my light switch have a leak? Does my override have a leak? the hissing seems to come from the light switch, but either line i pinch off(going into and coming out of the switch) the same thing happens, which is, it doesn't hiss until I let go of the line. Would this mean that somewhere between the firewall and my switches I have a problem? How can I override the switches to see if the rest of my system is in good shape?

I appologize for all the questions, and I hope someone can help.

Daniel
PS. My dash is almost completely out(upper and lower) so it looks like those speakers are finally going to be replaced and tach will probably get an overhaul because its off by about 1300 RPM. I hate "while Im at it"s. I always get sucked in......

Jvette73

I would guess that where ever you hear the hissing, it could be the leak. Listen closer for the leak using a short section of garden hose as a stethiscope.

noxqsz

Daniel;

I have a troubleshooting guide for 73-79 models that provide guidance to check out every part of the headlight actuating system with the use of only a hand-held vacuum pump and a pair of vise grips. It uses complete descriptions and illustrations of each component to help you through the process. I'd be happy to send you a copy of it. I'm trying first to scan it and send it that way. Failing that, if you have a fax number where I can send it, I'll try faxing it to you. E-mail me and let me know if you're interested.

Jughead

I don't know if this will work on a '77, but when I bought my '70 and for about 18 months the headlight doors would not open. The lights worked but the doors wouldn't open. When I need the doors open I opened them by hand, raising them until they were in the "locked" position. To lower, reach your arm thru the center grille opening and find the base of the headlight door. You should be able to feel around for the threads on the end of a thin(1/4in) bolt. There's a bolt on each door on the inboard side. Gently push down on this bolt and the door should lower. Watch that your hand doesn't get caught!

Mack

Have you tried this yet:
http://www.members.home.net/awsvette/vacuum.htm

still-learning

Daniel,

Definitely follow the vacuum troubleshooting tips listed above. I have a '77 and I have definitely experienced the same problems. I went from the headlights being REALLY slow to not functioning to now one is a little slow. (I know what the problem is but I am still on parts restriction w/ my wife. :D )

A couple of key places where it went bad in my car:
- Vacuum Reservoir Tank - That main part you were talking about was bad in my car. I just bypassed it. This means that you can't raise or lower the lights when the engine is off...
- Head Lamp Actuator Seals - These are famous for going bad. They are listed in the troubleshooting tips above. A CHEAP fix w/ only a minimal amount of labor.
- Head Lamp Relay Valve - In the '77 there is one for each headlight. One of these is what is currently leaking in my car. If I remember correctly they are couple hundred bucks...

Good luck!! For people who are like me (mechanically challanged) this is a fun project because you can do the work yourself and not have to delve deep into the mysteries of engines!! :crazy:

Tim M.

jerryp58

Even though I often do it myself :crazy: , I'm not suggesting that you replace parts instead of trying to track down the problem, but, when my lights did the same thing, I went ahead and replaced the headlight switch. It was about $20 (I think) and I could replace it by dropping the steering column, loosening the driver's dash and reaching in behind to replace the switch (I didn't have to pull the dash off completely). That solved the problem.

I also bought the "Troubleshooting the 1968-1982 Coorvette Headlight and Wiper Door Vacuum System" by Frank C. Prow II, from Zip for about $5 when my driver's headlight wasn't opening as quickly as I thought it should. I thought it was going to be a bad actuator seal, but it ended up being a pin hole in the actuator itself. I was lucky and was able to solder the hole closed.

I'm not sure if all of this rambling is helpful, but Good Luck.

79MakoL82

Personally, I don't get any hissing noise from my light switch and therefore have the gut feeling that that is your problem. You should not have air escaping from anything in that area. The tube in the front that you identified as your reserve is correct and the rest of the system sounds like it is hooked up correctly. The canister in the fender was on earlier models (that's why it's good to get a year specific Assembly Instruction Manual and shop manual, as they pertain to your specific year). The link in the previous post is an EXCELLANT troubleshooting guide. I printed that out when I was working on my headlights. If you need instructions on replacing the actuator seals, ZIP products has an excellant "how to" on their site. However, as I said, I think your problem is in your light switch.

Also, if you headlights are stuck up, they could be C5 headlights!!!! :lol: :lol: :lol:

OK, I'm going to take cover now.


[Modified by 79MakoL82, 3:54 PM 8/23/2001]

cgebert

Get the headlight troubleshooting guide. It's worth it. Sears has vacuum gauge sets. You'll need that as well. It'll probably just turn out to be one of the actuator seals. Zip sells the seals and has a guide on their site for installing them.