Odd Headlght Problem
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Instructor
Joined: Dec 2006
Posts: 201
Likes: 3
From: Lee's Summit Mo
St. Jude Donor '07
Odd Headlght Problem
I have had my '70 for about three months and since it had a few vacuum bug-a-boos, I have studied and learned exactly how how the system works. Ended up replacing both headlight relays as they both tested bad. Things worked pretty much as it should.
On a trip home the other evening, I turned on the lights and the left did not come up. I tried the switch and override valve several times and it never came up. I connected a small vacuum pump to the green line going to the actuator when I got home and it came right up.
I reconnected the hose and started the car and it worked perfectly several times, both with switch and override. A little later I took it for a drive and pulled the switch and the left one did not come up. Several times on both switch and valve. It works fine mechanically, opened and closed by hand with little effort.
The only thing I can figure is the spool in the relay is sticking and the spring will not push it down. I got the new relays from Zip and they tested perfect.
What am I missing? What say you guys?
On a trip home the other evening, I turned on the lights and the left did not come up. I tried the switch and override valve several times and it never came up. I connected a small vacuum pump to the green line going to the actuator when I got home and it came right up.
I reconnected the hose and started the car and it worked perfectly several times, both with switch and override. A little later I took it for a drive and pulled the switch and the left one did not come up. Several times on both switch and valve. It works fine mechanically, opened and closed by hand with little effort.
The only thing I can figure is the spool in the relay is sticking and the spring will not push it down. I got the new relays from Zip and they tested perfect.
What am I missing? What say you guys?
Drifting
Joined: Oct 2020
Posts: 1,566
Likes: 574
From: Wisconsin
I have had my '70 for about three months and since it had a few vacuum bug-a-boos, I have studied and learned exactly how how the system works. Ended up replacing both headlight relays as they both tested bad. Things worked pretty much as it should.
On a trip home the other evening, I turned on the lights and the left did not come up. I tried the switch and override valve several times and it never came up. I connected a small vacuum pump to the green line going to the actuator when I got home and it came right up.
I reconnected the hose and started the car and it worked perfectly several times, both with switch and override. A little later I took it for a drive and pulled the switch and the left one did not come up. Several times on both switch and valve. It works fine mechanically, opened and closed by hand with little effort.
The only thing I can figure is the spool in the relay is sticking and the spring will not push it down. I got the new relays from Zip and they tested perfect.
What am I missing? What say you guys?
On a trip home the other evening, I turned on the lights and the left did not come up. I tried the switch and override valve several times and it never came up. I connected a small vacuum pump to the green line going to the actuator when I got home and it came right up.
I reconnected the hose and started the car and it worked perfectly several times, both with switch and override. A little later I took it for a drive and pulled the switch and the left one did not come up. Several times on both switch and valve. It works fine mechanically, opened and closed by hand with little effort.
The only thing I can figure is the spool in the relay is sticking and the spring will not push it down. I got the new relays from Zip and they tested perfect.
What am I missing? What say you guys?
New components are hit or miss these days all over.
Melting Slicks
Joined: Feb 2018
Posts: 2,325
Likes: 720
From: Marietta GA
Have you tested the small vacuum one way valve located behind the carburetor? Also what is is the hg vacuum reading when your engine is running? Do you have power brakes, are they operating correctly? Are all the vacuum hoses new, or in good shape with no cracks, does the vacuum for the hvac system operate ok? The vacuum for all systems works fine on my 73, as long as the engine is running, (new hoses, relay valves). I have a leak somewhere, maybe the vacuum tank, but have never been able to find it. To find hidden leaks, sometimes a smoke machine is called for. The headlights lights work fine, as long as I open/close them while the engine is running.
