Headlight System Question
Thread Starter
Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
Headlight System Question
I found a bunch of headlight system posts, but none with this question / issue(?).
I just fixed up the headlight system and the lights open and close with the switch and under dash bypass the way they should. FYI - new headlight switch, actuator seal kit, new actuator relay, new check valve. Car is a '77 if that helps. Have checked all vacuum lines and they are in good shape. Vacuum tank is bypassed as it does have a leak somewhere - have not nailed that down yet.
When I open or close the headlights, the rpm raises a small amount - about 100 - 150 rpm. RPM drops back to normal idle as soon as they are full open or closed. Would seem to be a vacuum leak somewhere, unless this is typical of the system?
Thanks for any advice,
Adam
I just fixed up the headlight system and the lights open and close with the switch and under dash bypass the way they should. FYI - new headlight switch, actuator seal kit, new actuator relay, new check valve. Car is a '77 if that helps. Have checked all vacuum lines and they are in good shape. Vacuum tank is bypassed as it does have a leak somewhere - have not nailed that down yet.
When I open or close the headlights, the rpm raises a small amount - about 100 - 150 rpm. RPM drops back to normal idle as soon as they are full open or closed. Would seem to be a vacuum leak somewhere, unless this is typical of the system?
Thanks for any advice,
Adam
Thread Starter
Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
Thanks for the response on this '75. I thought and was hoping that was the case. The rpm increase was so small and that's why I asked.Guess they are working perfectly then!
Adam
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
I have never noticed the idle speed change when my headlights raise or go down. I have been playing with this car for 42 years, so I'd notice something like the idle speed increasing like you say yours does.
It would seem to me that you have a vacuum leak on the operation side, as opposed to the control side. Ideally, when you operate the headlight vacuum system, you're only drawing a small amount of air; the volume of the two actuators and the connecting hoses.
Good luck finding the problem,
Pete
It would seem to me that you have a vacuum leak on the operation side, as opposed to the control side. Ideally, when you operate the headlight vacuum system, you're only drawing a small amount of air; the volume of the two actuators and the connecting hoses.
Good luck finding the problem,
Pete
Le Mans Master
Joined: Dec 2007
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From: McHenry Illinois
Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Thread Starter
Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
Thanks guys! I appreciate the feedback and advice.
Wilcox, I was considering that today. I would still like to test the tank and see if I can find the leak. Going to use a tiny bit of AC compressor oil with dye in it. Should show me where the leak is when I pressurize the tank.
Thanks again!
Adam
Wilcox, I was considering that today. I would still like to test the tank and see if I can find the leak. Going to use a tiny bit of AC compressor oil with dye in it. Should show me where the leak is when I pressurize the tank.
Thanks again!
Adam
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Are you sure the reservoir tank has a leak? Or, could the check valve in the line going to the tank be defective? If the check valve is bad, the tank will only hold vacuum level while at idle.
The vacuum reservoir tank and a good check valve need to be in place for the system to work as intended. It will work without either...but not that well.
The vacuum reservoir tank and a good check valve need to be in place for the system to work as intended. It will work without either...but not that well.
Thread Starter
Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
Hey 7T1,
The check valve is new and I tested it - only allows airflow in one direction. The tank won't hold pressure with a vacuum applied and the headlights were really struggling to open when I had it hooked up. Bypassed it and the lights come up nice and smooth - still have a little bit of the lazy eye thing going on, but not bad. The car took a hit to the right front at some point in its life, so I'm guessing that it damaged the tank as well.
Adam
The check valve is new and I tested it - only allows airflow in one direction. The tank won't hold pressure with a vacuum applied and the headlights were really struggling to open when I had it hooked up. Bypassed it and the lights come up nice and smooth - still have a little bit of the lazy eye thing going on, but not bad. The car took a hit to the right front at some point in its life, so I'm guessing that it damaged the tank as well.
Adam
Last edited by AdamMeh; Dec 7, 2012 at 11:33 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Well, if you really have a leaky reservoir tank, it is doing you no good. But, those can be easily patched...from the outside, if you can find where the leak is located. The 'lazy eye' syndrome is almost always due to worn out relay valves.