Headlight/wiper door vacuum agony

[Ed H.]

History

• Problem first showed as headlights opening shortly after starting the car. At first they responded and closed using either the override or headlight switch.
• Then it began to require a fair vacuum (> 2K, closed throttle, most success was going down a steep grade) to get them to close.
• Curiously, at night they would reliably close when lights shut off. This would happen even when engine shut off first. Then only the left closed one time. Now neither.
• Somewhere along here, the wiper door began to open on its own, and now nothing will convince the lights or wiper door to close (other than as referenced above)

[Patrick H.]

Re: Headlight/wiper door vacuum agony

The short answer is that there is a vacuum leak in the system. When you find that leak - or leaks more likely - you will have the problem fixed.
The most common leak locations are the relays at each headlight canister and for the wiper door, as well as the switch in the wiper door trough.

Another not uncommon location is original hoses being a bit loose where they attach to an item. I have found that a piece of shrink wrap tubing placed on the item increases the OD enough that you can reinstall an original hose.

[Joseph S.]

Re: Headlight/wiper door vacuum agony

Ed, Disconnect the 3 Yellow stripped hoses at each relay and block them off. Now test your vacuum ability. If you still are loosing vacuum you may have a crack in the supply can. If you do have good vacuum now, reconnect each relay one at a time until you see which one is bad. I have found that 2 out of every 3 new relays are bad out of the box!

[Mark E.]

Re: Headlight/wiper door vacuum agony

Good advice from Patrick.

It sounds like your smoke test indicates a bad light switch. There shouldn't be any escaping air or vacuum there.

Another method for troubleshooting is to disconconnect the vacuum supply line at the intake, and connect a vacuum pump and gauge to it using a loooong vacuum hose. Position the pump outside the garage and apply vacuum to the system.

The idea is to energize and use the system in a quiet environment with the engine off so you can hear leaks. Use small vice grips to pinch off various hose segments to help isolate problems.

Vacuum purge is at the bottom of the relays.

[Patrick H.]

Re: Headlight/wiper door vacuum agony

Ed, Disconnect the 3 Yellow stripped hoses at each relay and block them off. Now test your vacuum ability. If you still are loosing vacuum you may have a crack in the supply can. If you do have good vacuum now, reconnect each relay one at a time until you see which one is bad. I have found that 2 out of every 3 new relays are bad out of the box!

Bob Demmel restores the relays.
It's never worth buying a new one as long as you have a core. There is a manufacturing defect that essentially makes the current reproductions so they cannot seal, and therefore will leak.

[Ed H.]

Re: Headlight/wiper door vacuum agony

Ahhh, some more pointers. The sad aspect is that Danny McGee, who did all the work is no longer with us... I believe all the components are new, but... and as pointed out, the new is equally suspect by definition.

I figured that the headlight switch has to be a prime suspect. It will be a bit but i'll get back on this.

Thank you, Gentlemen.