1968-1972 Wiper Door Actuator Plug and Boot Seal 3 Piece Kit
1968-1972 C3 Corvette Headlights operate on vacuum supplied from your engine while it's running. The first thing to do when working on your headlights is to obtain a good repair manual.
Your diagnosis of the C3 Corvette Headlight system should be a process of elimination. Start by checking the vacuum from the engine itself. It should read 18-20 inHG (inches of Mercury) on a good motor, but you should have a minimum of 10-12 inHG to properly operate the system. Once you have established your baseline, this is what you should use when reading the rest of the system. If you check any hose further down the line and read more than a 2-3 inHG loss, then you have a leak in your system. Also, if the leak is very bad you probably have a rough idle condition as well.
The system transfers vacuum in this order:
1) Engine
2) Filter
3) Check valve where it then Y's off
A) with the small side going to the Headlight Switch (Port #2)
- other side of headlight switch (Port #3) goes to the Override Valve (Lt Blue side)
- Override Valve (White side) goes to the T between the top of the Control Valves
B) the large side going to the vacuum tank
- then exits to the middle position on each of the Control Valve Relays, (Yellow hose)
- then based on switching position on the Control Valve Relays: Red line on hose runs to front of Actuator to close headlight, Green line on hose runs to back of Actuator to open headlight.
Common problems: Leaky check valves, will cause the headlamps (or wiper door) to pop open when you shut off the motor. Also, the "winking" syndrome, one headlight up and the other down, is usually caused by the control valve having a leak in the diaphragm or is leaking around body to control chamber section. Hose routing being bent or kinked, especially after someone has recently worked on the car.
The vacuum actuator on 68-72 cars is located in left front fender behind wheel, 73-79 cars use the front crossmember behind the bumper cover, and the 80-82 use a "coffee can" type of actuator located in the front end attached to the radiator support rod by a clamp.
Tech Note: As it applies to this part, the term Actuator and Canister have the same meaning.
Also known under these part numbers: (For reference only)