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With the engine running and providing the vacuum source, your lights should raise and lower provided the relays and actuators are in good shape..
Thank you. That’s what I thought. I’m going to refurbish the actuators and relays this weekend to make sure they are good. I’m pretty sure I’m getting good vacuum just not holding in the tank.
Last edited by Bluesting70; Aug 11, 2021 at 06:32 PM.
Get any Vacuum source besides the Engine and a long hose. A refrigeration Vacuum Pump is what I use but any car sitting in the driveway will work fine. Run the Hose into your shop and hook it up to the Hose leading to the Intake were it normally gets it. Now that its quiet with no Engine running You can hear what's going on. In no time at all the sound of a Vacuum Leak will lead You right to the trouble spot. Probably something Very Very simple to fix.
Get any Vacuum source besides the Engine and a long hose. A refrigeration Vacuum Pump is what I use but any car sitting in the driveway will work fine. Run the Hose into your shop and hook it up to the Hose leading to the Intake were it normally gets it. Now that its quiet with no Engine running You can hear what's going on. In no time at all the sound of a Vacuum Leak will lead You right to the trouble spot. Probably something Very Very simple to fix.
I’m still trying to salvage my vacuum head light system. Does anyone know what effect plugging the vacuum hose from the T to the wiper solenoid would cause? I ask this because I no longer use the wiper door with a long hood and I want to possibly plug those hose off as I might have a leak from the source to that T not allowing the headlight switch to hold vacuum.
unhook the tank. run a t fitting in place of the tank. unhook the T fitting to the wiper actuator. run vacuum hose straight from the intake to the T going to the actuator side of the relays. they should open and close as you unhook and reconnect the hose. can you pull the headlights open by hand? if not, the relay may well have a bug nest plugging the vent in the relay. if you can't make headlights work with the relays, start with 1 big vacuum line and try both sides of both actuators one at a time. i can pull one headlight open or closed sucking on the hose like a 20 dollar *****. so it doesn't take that much vacuum to run these. there are better vac diagrams, but this one works.
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Last edited by derekderek; Sep 1, 2021 at 06:06 PM.
There’s a series of videos on you tube made by “Problem Solver Garage” and one of his videos covers headlight vacuum and wiper door vacuum troubleshooting in detail.
Look for it on you tube or the Google machine.
Best of luck!
Greg
I appreciate the support from everyone. My relays are new and tested. The actuators I just rebuilt and tested. Im fairly certain the reserve tank has a leak but I believe they worked before even with the leak. I’ll have to try plug the manifold vac line to the solenoid as that’s the only thing I haven’t tried and that may be where the leak is that’s preventing them to open and close through the switch.
Well, I get one to open and the other shortly follows suite. But then neither will close at all. I didn’t run the car long so maybe I just need to let vacuum build for a longer period of time. Plus a good excuse to go for a morning cruise today!
The hose should go from the engine side of the headlight switch to the bottom of the pull down switch.
i don't think it makes any diff. the switch either stops or allows vacuum to be seen by the relay. plus, the bottom of the pull down switch is the end with the little stick one pulls down. which is shown pointing up in the diagram. bluesting, you need to remove the leaky tank from the circuit. what year car? these tanks are not easy to remove. but i believe they can be onbolted and flopped around a bit. vac pulls IN. any epoxy or even duct tape patch on the outyside will stop or reduce leakage a lot. but if you put a T fitting in place of the tank, you will have better vacuum both to the headlights and to the engine than letting the leaky tank allow air in.
Last edited by derekderek; Sep 5, 2021 at 07:27 AM.
i don't think it makes any diff. the switch either stops or allows vacuum to be seen by the relay. plus, the bottom of the pull down switch is the end with the little stick one pulls down. which is shown pointing up in the diagram. bluesting, you need to remove the leaky tank from the circuit. what year car? these tanks are not easy to remove. but i believe they can be onbolted and flopped around a bit. vac pulls IN. any epoxy or even duct tape patch on the outyside will stop or reduce leakage a lot. but if you put a T fitting in place of the tank, you will have better vacuum both to the headlights and to the engine than letting the leaky tank allow air in.
Me thinks, The headlight switch also exhausts signal vacuum to the relays.
If vacuum cannot exhaust through headlight switch, headlight relays cannot change state.
Me thinks, The headlight switch also exhausts signal vacuum to the relays.
If vacuum cannot exhaust through headlight switch, headlight relays cannot change state.
possibility i hadn't considered. climb under and look up at the relays. the round hole is the bottom of the relay valve in the relaxed-no vacuum state in this pic.
posted pic twice. oh well. you may have to remove a piece of foam that blocks your view of the relay valve. then have somebody turn lights onn-off while watching to see movement of the valve piston.
Last edited by derekderek; Sep 5, 2021 at 01:13 PM.
possibility i hadn't considered. climb under and look up at the relays. the round hole is the bottom of the relay valve in the relaxed-no vacuum state in this pic.
posted pic twice. oh well. you may have to remove a piece of foam that blocks your view of the relay valve. then have somebody turn lights onn-off while watching to see movement of the valve piston.
Yes, the internal spool of the relay will (should) move up and down.
The relay only uses a vacuum signal from either switch to change the spools state.
Didn't you just rebuild a relay not to long ago?
The exhaust port in your photo on the bottom of the relay is the exhaust port for the headlight actuator(s).
The actuator(s) also need a place to exhaust.
I have new relays and tested. Rebuilt the actuators. I measure vac at both ports right after the check valve and got 15 inches. Interestingly enough, I get less than 2 inches at the hose that comes from the check valve to the switch. I haven’t solved that yet but can’t think of why it would drop on that end of the hose.
Last edited by Bluesting70; Sep 5, 2021 at 05:13 PM.
I have new relays and tested. Rebuilt the actuators. I measure vac at both ports right after the check valve and got 15 inches. Interestingly enough, I get less than 2 inches at the hose that comes from the check valve to the switch. I haven’t solved that yet but can’t think of why it would drop on that end of the hose.
I know on a 77, the small vacuum hose from check valve tees and also feeds the heater and a/c controls. If you're only getting 2" at the manual override switch I would try a temp hose from small port on check valve directly to manual override, just to test.
Troubleshooting Headlight Vacuum
