Another headlight vacuum question
Thread Starter
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
Another headlight vacuum question
I've researched and found no match to my problem, as far as I can tell.
Previous owner had butchered the underhood vacuum system in my '80. I bought and installed a new line kit with no real problems. All the vacuum tanks, etc were still in place. I used the instructions with the kit as well as my AIM to get it all correct, but I still have no working headlight doors. When I pull out the headlight switch, I hear a quick vacuum noise like the system is engaging. No lights pop up. They burn fine and I can manually (and inconveniently) pop them up for night driving. No leaks that I can locate, and I get good vacuum at the two inline valves, splitter, whatever behind the carb. Just nothing to pull or push the headlight buckets.
I'd really like to fix this but I don't know where to go from here.
Previous owner had butchered the underhood vacuum system in my '80. I bought and installed a new line kit with no real problems. All the vacuum tanks, etc were still in place. I used the instructions with the kit as well as my AIM to get it all correct, but I still have no working headlight doors. When I pull out the headlight switch, I hear a quick vacuum noise like the system is engaging. No lights pop up. They burn fine and I can manually (and inconveniently) pop them up for night driving. No leaks that I can locate, and I get good vacuum at the two inline valves, splitter, whatever behind the carb. Just nothing to pull or push the headlight buckets.
I'd really like to fix this but I don't know where to go from here.
Instructor
Joined: Aug 2007
Posts: 200
Likes: 0
From: Falls Church Virginia
Casey, just my two cents. Need to rebuild or replace your headlight vacuum canisters. After you know all hoses are right location using the diagrams. I went through everything to avoid replacing canisters but more than likely that is the problem. Thanks
sgm
sgm
Instructor
Joined: Aug 2007
Posts: 200
Likes: 0
From: Falls Church Virginia
Agree dgood but the seals is what should be replaced. The rubber boots are used to keep dust, dirt and stuff off the shafts. And if the diapham is bad its no go. I would replace the whole canister but thats just me. I have found W/A/D/R replacing entire part is the way to go. But again thats just me. Thanks
sgm
sgm
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
You can test the actuators for leaks. Attach a hose. I can't remember which it is but sucking or blowing will make them go up. If you find its like blowing through a straw...no resistance the rubber boot is gone and needs replacing.
Jim
Jim
Racer
Joined: Mar 2008
Posts: 434
Likes: 0
From: Triangle Area NC
Disconnect the vacuum hose going to the resevoir. Hook a small vacuum pump ( a cheapie used for brake bleeding from China Freight or the like is fine) to replace the hose coming from the light switch and see if your lights raise.
If they do, start working back towards the dash and vac source. If they don't start working forward towards the lights (starting with the vacuum valve(s) .
If they do, start working back towards the dash and vac source. If they don't start working forward towards the lights (starting with the vacuum valve(s) .
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Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
The vacuum canister seal is usually the component that fails and causes headlight actuator problems. Rebuild kits are inexpensive and worth it as a first try to fix the problem. I had one that was malfunctioning, rebuilt it, and the other one crapped out. Rebuilt that one and they both have been working all summer. They don't rise at exactly the same time but as long as both of them raise up I really don't care.
Rick B.
Rick B.
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
I'll throw in another vote for getting a rebuild kit for the actuators. I did that on mine and it fixed the problem. What I noticed that caused me to rebuild them was that the dust boots were disintegrated. Cheap fix too, about $25 per actuator kit.
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
If you use a hand vacuum pump you should be able to hear if there are leaks.
As stated above, start with the pump connected to the actuator (test both the front and back ports as they should retain vacuum in both up and down positions) and move your way back towards the interior.
cc
As stated above, start with the pump connected to the actuator (test both the front and back ports as they should retain vacuum in both up and down positions) and move your way back towards the interior.
cc
Burning Brakes
Joined: Apr 2009
Posts: 807
Likes: 2
From: VIRGINIA BEACH VIRGINIA
sgm 2004, you are right. I wasn't sure what they were called. I replaced my seals and they have been working good for the last couple of years. Lucky I guess because the rods are a little rusty. I have heard that the switch under the dash fails quite a bit or it is hooked up wrong.
Racer
Joined: Oct 2007
Posts: 270
Likes: 0
From: Chapel Hill NC
I would like to know more about this statement.
All my headlight vacuum components and hoses have just been replaced. The passenger headlight pops up fast... but the driver side headlight comes up about 8 seconds later... and slower.
What would be the cause of this?
They both close immediately.
Drifting
Joined: Jul 2004
Posts: 1,695
Likes: 65
From: Kissimmee fl
Finalist 2021 C3 of the Year - Modified
2017 C3 of Year Finalist
Cruise-In VIII Veteran
St. Jude Donor '07
The vacuum holds them down. When the fail, they fail to the up position. That is why you see C-3s running around with one or both headlight up.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Here's a troubleshooting guide.
http://www.corvette-101.com/vacuum.htm