C3 Headlights.......Work? Yeah Right!
Thread Starter
2nd Gear
Joined: Jun 2009
Posts: 2
Likes: 0
From: Palmerston North
C3 Headlights.......Work? Yeah Right!
Anyone having a full head of hair after having C3 Headlight problems, I would like to meet them lol. Im having big probs with head lights that wont work correctly. I have replaced everything, hoses, actuators, relays, check valve, even the headlight switch. The inlet manifold has had new gaskets fitted to make sure the engine has good vacume. Engine running, headlight switch "on" If I pull the left H/Light up by hand the right one comes by its self. Turn the lights "off" the right one goes down good, the left trys and after 30 odd seconds it goes down. They were working ok (a little slow) then just stopped working all together. Can anyone suggest anything. 
Racer
Joined: Mar 2002
Posts: 406
Likes: 1
From: Maroochydore QLD
Are you sure you got the colors of the hoses on the right colors of the tubes of the actuators?
Also, isolate the vacuum source for the headlights from all other vacuum hoses, eg. dash controls etc, then start testing from the engine to the actuators.
Dennis
Also, isolate the vacuum source for the headlights from all other vacuum hoses, eg. dash controls etc, then start testing from the engine to the actuators.
Dennis
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Try pinching the yellow hose before it goes into the left relay and then operate the headlights and see how the right light works. If the right works well then you probably have a leak in the left actuator or relay. If the right is still slow then I would have to guess the vacuum reverse tank is leaking.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Slow working lights are also the result of low vacuum from some performance camshafts....you can replace everything and the lights will still respond slowly..normally its the closing that stands out. I just live with it
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Most performance camshafts will produce above 15" vacuum on deceleration and a tight system will store this for headlamp operation.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
M. Ward's advice is precisely correct. You need to get a vacuum system diagram (for your year car) and a troubleshooting guide so that you can learn how the system is supposed to work...and then to diagnose it properly. Probably 90% of the vacuum system faults in "C3-land" can be resolved for less than $20; half of those can be fixed for FREE. But, you need to know how the system is supposed to work and how to diagnose it in a simple but organized way, so that you can quickly and easily find the solution.
I got my "68-82 Vacuum Troubleshooting Guide" from Rik's Corvette Parts (www.riksvet.com). Good luck.
I got my "68-82 Vacuum Troubleshooting Guide" from Rik's Corvette Parts (www.riksvet.com). Good luck.
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Le Mans Master
Joined: Jan 2007
Posts: 5,485
Likes: 7
From: Peekskill NY
Check these links out. They may be helpfull.
http://www.corvette-101.com/vacuum.htm
http://www.corvettepartsblog.com/vet...rvette-vacuum/
http://www.corvette-101.com/vacuum.htm
http://www.corvettepartsblog.com/vet...rvette-vacuum/
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
With all the parts you have replaced it could be a bad hose connection (sometimes the hose cracks there) or a vac. tank leak. You can bypass the tank & test each side.
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
Your profile says you have an 82 so IIRC you have a coffee can vacuum canister. You might check it for leaks or bad connections.
With new hoses, relays, actuators and check valve there isn't much left. As said above make sure you have all the correct colors on the correct connections. It's pretty easy to mix a couple around.
cc
With new hoses, relays, actuators and check valve there isn't much left. As said above make sure you have all the correct colors on the correct connections. It's pretty easy to mix a couple around.
cc
Drifting
Joined: Apr 2008
Posts: 1,565
Likes: 2
From: Sparta Mo.
I had a problem where the main feed line to the vacuum tank was blocked by pieces of the in line filter. If you pull the filter off and you can see through it, replace the hose that goes from the intake the vacuum tank. I also replaced the tank with a much larger tank to store more vacuum.
Here's a cross section of the blockage.
Here's a cross section of the blockage.
Safety Car
Joined: Sep 2005
Posts: 4,062
Likes: 103
From: Southeast, Tennessee
St. Jude Donor '09 thru '26
i had similar problems several years ago when i started to "rebuild" my 78 pace car. after screwing around in much the same way you did (changing everything eventually), i discovered that one of the new headlight actuators was actually bad (it had a bad internal diaphram). replace it and all is good with the world. i guess my point is that after double checking the lines and making certain the check valve is installed in the correct direction and the filter is clear, you might just want to try "swapping" the vacuum lines between the actuators to see if the results are reversed. if so, either the boot or the internal diaphram of the actuator is dmamged and not functioning correctly.
