Msbfdx

My '73 Coupe right hand head light is slow to open and close. I have replaced all springs, all vacuum lines (I literally mean all... from the headlight switch and bypass valve, all engine lines and all lines to-from headlights, relays, actuators and tank) and new filter and check valve. There doesn't appear to be any binding in either mechanism.

I haven't changed the actuator rod seals or boots. Any thoughts on whether it is relays or actuators rod seals?

Many thanks in advance for advice and help.

Mooser

Swap the lines from the switch to the actuators and see if the problem stays (actuator problem) or moves to the other light (switch problem)

To check the actuator for diaphragm or boot, block off the front (straight) port and see if you can still pull the rod out (even with some drag) if you can, the seal boot is leaking, install a new one.

Blocking the rear port (90 deg one) and if you can move the rod, the main diaphragm is leaking and the unit needs to be replaced

HIH
M

Msbfdx

Many thanks. I will give it a try.

tejasak

Be sure to check the vacuum relays.

http://www.corvette-101.com/vacuum.htm#relay

7t2vette

It sounds like either the actuator diaphragm or rod seal is the culprit. Following Mooser's advice, you should be able to quickly determine which one it is.