Me, moron. I didn't see the subject heading of 67GP. I can't edit post.
I'm guessing the headlight switch got damaged. It's a standard headlight switch with a vacuum switch attached. There's a rubber gasket inside that seals vacuum. If lucky, the vacuum hose was loose and got looser. My connector had gotten loose which I "fixed" by putting some heat shrink on the connection ports on the switch - now it has good vacuum to actuator (Ames has new connectors - $16 for 2 if they fit [68s must have had two actuators]). Note if you buy a whole switch (Ames $80) - the 67 parking lights don't come on with the headlights, but the 68s do - the previous owner got a 68 switch so PLs are on with HLs - looks cooler but not original).
Other possibility is it's not the switch but something was borderline and went bad from using it like that. Best way to check system is put a vacuum gauge on the supply line right off the carburetor to measure full vacuum, assuming no leaks anywhere else - mine has 20 inches at fast idle. With headlights hooked up I had 15 - also leaking some from heater control (line goes through upper center firewall) so I disconnected/plugged it. You can check the switch under the hood - there's a supply (easy to see), then Open and Close lines that go to actuator (can't tell). The lines to/from the switch feed through a 3-hole grommet to the right (looking from front) of the master cylinder). A vacuum tank is hooked to the supply line - this sometimes leaks too (plug line going to it to check it - it's under the fender). Disconnect and check all lines - if the switch or lines going to it are leaking, you'll have full vacuum when plugging the supply, but not when plugging Open and/or Close (of course you need to turn headlights on and off when checking switch/lines for leaks).
To get the switch out, you'll have to pull AC duct (if equipped). Knob pulls out by turning on headlights (switch all the way out), then pressing a spring loaded button release on the switch. Line 2 (center) connects to vac supply, 1 opens the headlights, and 3 closes them (one of my switches wasn't marked, but you can tell 1 and 3 by operating the switch).
To check the actuator, I had to pull the valance (see below - I could barely get my hands in there). Disconnect vacuum hoses (had to pry them off with screwdriver because they were stuck), then plug them and check vacuum. If you have full vacuum with these actuator lines plugged when turning headlights on and off, the actuator is leaking.
To remove the actuator, you have to pull front valance (no need to completely remove bolts on ends because valance is slotted where it attaches to front fenders), then remove hood latch (3 bolts), center support (from under car - 3 bolts in lower frame and 2 up top), remove actuator link from headlight mechanism (C-clip on end) and 3 screws or bolts to get the actuator out (may want to disconnect the spring first). You've got to take out the hood release rod/latch and actuator as one - a little twisting will do it (be careful with radiator right there).
You'll have to fix the actuator if you can't find a good used one - it seems they're not available anywhere. Ames has them for 68s but they mount completely different and nothing else looks similar. I'll write up how to fix one somewhere later. I have mine apart now. I suppose my vacuum seal for the rod got brittle (Ames must have these but they're not listed for 67s - the one in my car is newer), started leaking, likely sucked in water and rusted - then affected diaphragm. The front half had holes in it and where the seal goes in was rusted away - I fixed all that with plastic sheet and JB weld. But now had to take it apart (Note to self: always check that actuator seals before putting it back in and the car back together. Took me 3 hrs to get it out the first time - about 1/2 hr the second time). If you're lucky, you'll just have a bad seal (there's also a dust boot [$16/2 at Ames], but it's not necessary, though may help preserve the seal). Next most lucky is if there's some rust holes in the actuator body that can be patched (mine had much rust scale in it - I was able to shake it out). With the actuator in hand, connect both sides to the vacuum source - the actuator may work if leaking (without having load of headlight mechanics on it) but won't be very strong. You should see a drop in vacuum as the actuator rod moves, but it should rise to normal when actuator plate/rod hits its limit. If you never achieve full vacuum, the diaphragm likely has a hole in it - you can tell this by putting finger on other port while testing Open and Close. If it still doesn't get full vacuum when doing that, the case has a hole in it (they can be hard to see - like under where the dust boot flange attaches).
To get the actuator apart, you have to uncrimp the two halves. Start with a screwdriver (long with small tip) to pry it up a bit - then I used diagonal pliers to pry it up around circumference about 1/8" at a time - takes a while but turned out fine. Mine wasn't rusted at circumference, but maybe some are and chunks will come off. Might as well go for it, because it's no good anyway. You can fix a LOT of stuff with JB weld. Then separate the two halves, pull out rod with diaphragm and see what's causing the leak - if the rod seal is old, it will probably tear when doing this. I'm still working on how to patch the diaphragm. PlastiDip kind of sticks to the rubber but not well (it worked/held vacuum but wasn't strong enough to be reliable [you only want to do this once]). I have a spare diaphragm from a work part, but to install it, the two metal retaining plates have to be separated and that would create more work (there's a major stake on the end of the rod holding them together - this point carries a heavy load when closing or opening the headlights). I'm trying E6000 and cotton gauze to patch a 1/4" tear in the rubber - stuff takes 24 hrs to cure, maybe 72 hrs for full strength).
Hope this helps - at least you can check out the system. Good luck.
Monday, August 31st, 2015 AT 4:26 PM