Winking headlights

[Kurt G.]

This afternoon I went over to see if I cold help a buddy with some finishing touches on his frame off restoration. He's been fighting vacuum system problems and piling out hair.

Using a vacuum pump to avoid burning gass and heat, th pump us hooked up to the line that normally is on the manifold fitting so th pump supplies the pressure rather than the engine. Now the problem.

When the pump is turned on the wiper door actuator "opens" the door system and the headlight doors cycle, usually th left opens, closes and then the right side does the same. In addition, we can hear air running/ hissing thru the main line from the manifold to the metal check valve. We pinched off all the lines to the wiper door and headlights to see if we could isolate the leak to a line, as well as unhooked the lines to the override valves under the dash and plugged them off. The only two things that stopped the hissing was to pinch off the main vacuum line before the check valve or to pinch off the large line on the "back side" of the check valve before the first "T" in the line. All the actuators have been check and seem to be holding vacuum as have been the regulators.

After a little over 3 hours I was pulling hair as well. We made a call to a friend using a one of our three safety cards, now we're asking the audience. Anybody out there have any suggestions.

By the way, the only thing that didn't get check today is the headlight switch, which was tested before he installed it in the dash. Every other line was isolated/pinched off to block vacuum/airflow.

Let us know if you've had a similar problem and what fixed it. Oh, and by the way, the only hose that isn't new is the small line that "T's" off the main line and goes to the climate control valve/selector on the non-air car, but it was pinched off to isolate it

[Terry M.]

Re: Winking headlights

If you can hear hissing -- find out where it is coming from. The HVAC (heater/air conditioning) control is a prime candidate. Isolate that small vacuum line that goes into the passenger compartment (comes off of a plastic T fitting that is in the main line going across the top of the firewall – near the PB booster ISE) to get that POS out of the picture.

Relative to the winking & blinking == you must understand the design of the vacuum system. There are two systems:
1) control system. These are the small hoses that go to the relays (beside the brake master cylinder and two under the flags on the front of the car) and go under the dash to the interior controls (including the solenoid on the back of the tachometer) for the wiper door.
2) power system this is the larger hoses to the vacuum reservoir (conveniently located under the driver's side fender behind the wheel house) to the vacuum relay valves, and to the headlamp actuators.

The system is designed such that the control system has less volume in it (small hoses) and as the vacuum in the system goes down from ambient pressure the control system will be sucked down before the power system. The relay valves are spring loaded to open what they actuate if there is no vacuum in the control system (safety feature), so if the control system has a leak the power system gets sucked down first and the actuators move under the control of the relay valves in the rest position. As the control vacuum then overcomes the leaks the relay valves return to their controlled position and the actuators return to the desired position. Thus the headlamp and windshield wiper doors go up and down. Capisce?

Look for your leak in the control system. That hissing noise is likely in the control system. To find the source of the hissing use a several fool long piece of geater hose (any kind will do). Place one end near your ear, and move the other end following the vacuum lines. You will find the source of the hissing when it is loudest.