Hey guys have a 1977 c3 every time i start car headlights pop up but will not go down until i shut car off and then i have to manually push them down all hoses r correct could there be some type of vapor lock or something thanks

 

A bad Check Valve might be the problem. PG

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also when i turn headlights on before i start car only one side comes up this has me baffled
when i block vacuum on either relay light will not come up how could it be just one relay thanks a bunch

 

Were you messing with vacuum hoses before the problem started?
If the answer is yes you need to follow PG's diagram he posted for you.

Schoon

 

Welcome to the Corvette Forum. Did you check the manual pull valve below the steering column. I'm assuming that the 77s still had one.

 

There is only a limited supply of vacuum in the tank with the engine off, you no doubt exaust that vacuum, because the other side has a small leak it will not go up.
Do both sides go up with the motor on?
PG.