Well, another ? on the infamous vacuum headlight set up.

My lights have been working fine. Replaced the actuators about 2 years ago and no probs. They never were quick, but always worked.

NOW painful to see them attempt to go up. The pass side will make it after running for a minute and the drivers only half way. Checked for loose hoses: NONE Checke the vacuum: 15 lbs at idle should be ok.

the filter and check valve from the manifold line seem ok..

Light switch seems ok. If I pull the lock switch under dash, they stay up. If I push that in and turn lights off they go down...

So... I am thinking either 1) the tank is messed up (unlikely) or 2) need new relays at the lights.. Any thoughts or experience with this?? I think process of elimination says the relays, but before I dump $120 on new relays, I would like to get feedback.
Thanks in advance.

 

Vaccum hose is fairly cheap and if your lines haven't been replaced I think I would start there???

Kona

 

Thanks, I did not mention, but I already replaced them all That was the first thing I checked.. I have a sneaky suspicion it is the drivers side relay

 

very, very sneaky!

 

How well do they go down (once they're up!)?

 

You could run both lights off of the one relay you think is ok and that would test the one relay and see if it is holding its vaccum.

To test a relay, apply vaccum to the center port on the relays plastic body, put your finger over the bottom port and it should hold vaccum. Next apply vaccum to the port on the metal lid. This will pull the relay in, the relay should hold vaccum here. Pinch off the vaccum line so the relay will stay pulled in. Next apply vaccum to the center port on the plastic body again while placing your finger over the top port of the plastic body. It should hold vaccum. If at any point you are not holding vaccum there is a leak. If it is on the ports of the plastic body, you can rebuild the relays. Not too bad of a job. I have done several and they came out good.

Hope this helps.

http://www.corvette-101.com/

 

They go down drivers side first, then passenger side. not instant, but kind of quick. They have NEVER gone down together at once, or for that matter raised up at the same time Always worked though. It seems they finally petered out.

I will try this... Thanks.. The relays are about the only things I have not tested or replaced over the years.

Thanks guys!!

 

Then that would eliminate leaky diaphrams in that canisters. I believe that the relays need work or replacement.

 

Relays are typically the culprit after the seal on the actuator. Since you've replaced the actuators, I would agree that the relays need to be looked at.

Eddie 70's method of testing the relays works well. I would go one step further though. First check that both of the center hoses on the relays have good vacuum. Once you've determined that they do have vacuum, plug one and using the other one check that the actuator on that side is not the problem. Removing all three large hoses from the actuator. Then using the center hose, connect it to each of the other two hoses (use a plastic connector or a smaller section of hose to join them) one at a time. The Actuator should function and the headlight should come up and go down smartly depending on which of the two hoses it is connected to. Both assemblies should operate at approximately the same speed up and down. If they don't then part (or all) of the problem is with an assembly. (In that event I would look at the seal on the front of the actuator first. Don't confuse the seal with the dust boot that covers it. The dust boot is first to deteriorate, but the seal is underneath and is made of tougher material.)

If both headlight assemblies operate smoothly during this test then you definitely have a relay problem. Be especially careful in removing the relays as the screws that hold them to the cross brace tend to rust and like to break off.
Regardless of whether you rebuild your own relays or buy new ones, pay close attention to the small piece of foam filter in the relay. It is at the bottom (opposite) of the slide that is attached to the diaphragm. (The slide moves up and down to port vacuum to one side or the other of the actuator.) The small foam filter comes in all new relays and keeps dust from being drawn up into the relay and damaging the seals that allow it to work. These filters deteriorate rather quickly and fall out. You can cut a small (very small) square of loose foam and insert it in there to replace one. This will ensure your relays last a good long time.

I have also found a vacuum reservoir on one Corvette in which the vacuum fitting had rusted solid. The reservoir had good vacuum to it, but none made it to the relays. It seems on this one the fitting was at the bottom and moisture had collected in the reservoir causing internal rust which happily plugged the fitting! I ran a small drill bit through the fitting and everything worked fine.

I love these vacuum headlights…[I]

GUSTO