My right side headlight always came up way after the left one so I bought 2 new relays. Now they both come up quick & go down fine but when I shut the car off the right one pops back up ! Bad new relay ? (yes,the vac lines are all hooked up correctly)

 

Maybe the valve under the dash that holds up the lights to change the bulbs? I know this controls both headlights but just a thought...Other than that, I would assume it is a bad new relay. Just my 2 cents

 

I'll bet you a dollar that you have a bad vacuum check valve. Follow the vacuum line off the manifold. The first item you should encounter is a filter, second item you should encounter is the check valve. Replace both of those items, the parts together should cost under $20 and take 2 minutes to install.

 

VACUUM CHECK VALVE

DESCRIPTION:**The check valve has 3 vacuum ports; two on one side and one on the opposite.*LOCATION:**The check valve is near the rear of the carburetor, close to the intake vacuum fitting on the manifold.

FUNCTION:**The check valve enables the vacuum tank to store a vacuum supply when the engine is not running by preventing air from escaping.

TROUBLESHOOTING:**The check valve permits air to flow in one direction. Air can only pass from the side with the 2 ports, towards the side with the single port. You should be able to blow into either of the 2 ports opposite the single port. These 2 ports should hold vacuum when attached to a vacuum pump as long as the adjacent port is plugged. The end with the single port should not maintain vacuum pressure and you should not be able to blow air into this port. A leaking check valve may cause the headlamps to open when the engine is turned off; but this depends on the condition of the rest of the headlight vacuum system.* A bad check valve, where air travels in both directions, will allow all the air to escape from the holding tank and prevent operation of the headlights while the car is turned off.* A clogged check valve will prevent vacuum from being supplied to the system.

From http://www.corvette-101.com/vacuum.htm

 

That wouldn't explain why one works fine & one doesn't.

 

Is the rest of your system working perfectly? Are you sure the vacuum is always equal at both headlights? If not it's reasonable that only one headlight would open. It's simple enough to check.

 

They both work fine. Start the car, turn on the lights, they both come up fine. Turn off the lights & they both go down fine. Then shut the car off & the right one pops up !

 

almost always the check valve you ruled out previously.
you can easily check it by blowing/sucking through it.
should only pass air one direction.

 

Bad check valve.... Vacuum from the reservoir tank is not being maintained or it would stay down. That would be either because you have a bad check valve or you don't have a working reservoir tank.

 

I have a drivers side headlight that stops mid way up. Both close ok. I am going to replace check valve as well. The one I have might be an old style or wrong type ? I cannot

seem to find this design ? Anybody ever see this type one ?

 

Swap them and see if the results change and move to the other side.

 

After 9 years, lets start a new thread.