Hello everybody. I have searched this site, YouTube, and the Internet in general, for a “one stop shop” guide to troubleshoot the vacuum system for the headlight doors, in my case a 1969 Eliminator. I had a minor leak in my headlight door actuator, so I replaced it with a rebuilt one from Critter Creek Cougar (through National Parts Depot). Two days later, my headlight doors were open again. I know I need to start looking at the check valve, vacuum storage tank, and rubber lines, but I’m wondering is there a sequence that makes sense- for example start here and work your way there. I did read on here about how to test the storage tank by presurizing and submerging in a tank of water, but what about the check valve, rubber lines, and even the headlight switch? Is there a process to test them? Thanks in advance. Oh, before anybody recommends going electric, my car is all stock so I would prefer to keep it all original.
Don Rush, if you’re reading this, I think this would be great for your next “how-to” video!
New to the group, but this was actually my first project task as I tackled my first 1970 cougar, now have a 1969. Both had the same issue. Both equally frustrating to nail down, hence why I went the electric direction, but after getting everything out, i realized time spent on cracked hoses and that tank in the inner fender could have gone a long way to keeping that vacuum system working perfectly. Just my 2 cents, so I hope someone here has some good thoughts to help you along.
I used a Mighty Vac vacuum tester. Checked the actuator. The tank, took off the hoses and tested rach pipe one at a time, which found my problem. It was the supply line to the tank. The switch was changed out already because of a short for the dash lights caused by having the aftermarket radio grounded thru them. Off topic. But the 2 position plug for the stock radio is radio power and backlight power. Not ground.
You said doors were open after two days. FWIW, the original warranty spec was 18 hours closed. I know because my 70 actuator was replaced under warranty the first year - it’s a one owner and I keep records.
Since then I’ve tracked down small leaks multiple times. It’s most often the hose ends (last 3/8 inch) that lose grip. Mine are original hoses, some cut down a bit to get better grip.