headlight door vacuum for 69 charger

[C928BRAN]

should there be a check valve in the vacuum system for the headlight doors? i have no vaccum in the system, as soon as i turn the car off. other than that, the doors work fine.

[MaximRecoil]

There is no need to add a check valve. There is a vacuum reservoir which looks like a coffee can, located below the battery tray. This should store enough vacuum to allow the headlight doors to open or close once with the engine off.

Aside from the hoses, there are only 4 components to the headlight door vacuum system: vacuum switch, vacuum reservoir, and two actuators. The vacuum reservoir can be bypassed and the headlight doors will still work fine as long as the engine is running. Maybe that's been done to your car.

[C928BRAN]

I have the complete system. could i put a check valve in the system somewhere, and correct this problem?

[MaximRecoil]

There is no need for a check valve; there is no place that you could put a check valve in the system where it wouldn't be redundant. Engine vacuum only pulls in one direction, and it is already a closed system to prevent air from replacing the vacuum when the engine is turned off.

The system as-designed stores a certain quantity of vacuum after the engine is turned off (in the vacuum reservoir). If yours doesn't, then there must be a leak somewhere in the system. I'm surprised that your headlight doors open and close okay with the engine running. How long does it take for both of them to fully open and for both of them to fully close?

[resq302]

I have to disagree.  The coffee can looking thing under the battery tray DOES have a check valve in it at where the fitting that connects the hoses to is.  If there were no check valve, that vacuum reservoir can would be useless.  The reason why this is there is if you turn your car off and leave the headlights on after the car is turned off, you have enough vacuum to close the headlight doors.  I do know that the reservoir can is repro'd but I can't remember who sells them now.

[MaximRecoil]

I have to disagree.  The coffee can looking thing under the battery tray DOES have a check valve in it at where the fitting that connects the hoses to is.  If there were no check valve, that vacuum reservoir can would be useless.  The reason why this is there is if you turn your car off and leave the headlights on after the car is turned off, you have enough vacuum to close the headlight doors.  I do know that the reservoir can is repro'd but I can't remember who sells them now.

I wrote my reply in the context of adding a check valve to the system, because that's what the OP asked about. I said "there is no place that you could put a check valve in the system where it wouldn't be redundant".

[resq302]

Ok, misunderstood your post.  The only way adding another check valve would be beneficial is if the check valve in the vacuum canister was bad.

[C928BRAN]

which hose would i need to put the check valve on? the one that runs from the engine to the can, or the one that runs from the can to the switch?

[resq302]

I would say it would need to be the one from the can to the engine.  This way you have the vacuum reserve in the can still unless you have a leak somewhere.  Before you go cutting your lines, I would double check to see if the check valve in the vacuum canister is good or not.