Just started seriously working on my 1970 cougar. The headlight covers won’t open.
The covers will move freely if manually lifted, and the vacuum diaphragm holds tension.
The lines from the diaphragm to the check valve are good, and ive tried the valve in both positions.
The green and yellow lines from the check valve to the switch appear fine.
The resivor white resivor line is cut so I assume
that’s the issue. However, I can’t find the other end it might connect to.
From the interior switch, there is a white line that looks like it goes to the vacuum tree.
From the tree, one line runs to a 1 to 2 vacuum conversion that has one end blocked and another end that appears to run to the switch.
Any help or insights would be great.
Here is the schematic you need.
Yellow and Green do not connect to the check valve, they only run from the headlight switch through the bypass valve to the headlight actuator. The check valve splits the manifold vacuum into two white lines. One is the vacuum source to the headlight switch, and the other runs to the vacuum reservoir under the drivers side fender behind the headlights. The check valve only allows air to flow towards the manifold when the engine is running. When the engine is off, it seals off the manifold isolating the vacuum to the two white lines. Now the reservoir is the vacuum source that holds the headlights closed.
There should be coil springs on your headlight door shaft that holds the doors open with no vacuum present.
Looks like the white line from the resivor to the check valve is the one thats cut.
Ill connect it and see if that helps.
That diagram is super helpful thanks!
With that line cut, you should have a manifold vacuum leak big enough to make the idle rough, and no vacuum at all to the headlight actuator up or down ports. The springs on the headlight door shaft should hold the doors open in this condition. The fact that your headlight doors stay closed probably means the springs are missing.
But if the actuator and reservoir are not leaking, and the headlight vacuum switch, the check valve, and bypass valve still work, you just might get the doors to open and close when you reconnect the reservoir. Point being that there is a lot of stuff that all has to work right to make our headlight doors open and close.
Fixed it.
With the diagram I went through and double checked all the lines. Turned out I had missed a crack in the line running from the vacuum resivor.
Got everything hooked up and at first they only opened with the lights off. Switched the lines running from the main diaphragm and its all good now.
Thanks again for all the help!
