Headlights

[outlaw]

I have a 70s vette and when turning the headlights off the right goes down with ease but the left stays up for quite a while, or until you start engine again and create vacuum before it closes.

what are the common symptoms??

[Cameron 77C3]

Ahh vacuum systems. ;53

Provided the light in questions mechanism is OK, not tight etc, etc, with motor off there is only so much vacuum stored in the reservoir tank.  A faulty vacuum check-valve near the carby or leaks in the system will cause vacuum to leak out very quickly once engine is off.

Any vacuum leaks can cause the problem.  Including the vacuum switch on the headlight switch, A/C-Heater Controls, Brake booster, Cruise control if fitted, Kick down on auto if fitted.  When I re-did my system with an after market check valve and all lines replaced and no leaks I can close my headlights with the engine off and partially open them back up again.

It's a fun job chasing it down.

All of this based on what I found with my 77.  Not to be taken as gospel, but hope it helps.

[Cameron 77C3]

Some of this may help

This website http://www.corvette-101.com/vacuum.htm#actuator

This thread here on this Forum http://www.nswcorvettes.com.au/forum/viewthread.php?tid=6216

[77CVT]

Yeah, the joys of a 30+ yr old car!

Turn 'em off with the engine running or convert to electric!  ;-)

[MADLT1]

i replaced my vacume lines about 12 years ago,they worked excellent up until late last year,i think mine mght be the sels in the actuators,if you replace your there are 2 seals,inner and outer,this is a common pro,get under you car and see if the rubbers are perished.

[77CVT]

The important one is the one way valve coming off the manifold line - when that goes it stuffs up everything else.