C3 Headlight issues Imagine that
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2nd Gear
Joined: Jun 2020
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C3 Headlight issues Imagine that
I have a 1977 C3 left headlight opens correctly,Right wont go up without help both lights close normally. I have trouble shot and the issue seems to point to the right Regulator.Not feeling real confident that I am troubleshooting it correctly.. Put a new headlight switch in no change overide seems to be working correctly filter and check valve test good vacuum hose all seem good. Left light assembly goes up and down but feels tighter then the right . Removing the up and down hoses on the right actuator individually and testing seem to function normal.any advice will be appreciated. I hate throwing parts at a problem really hate buying parts I dont need.
Thanks Learmec
Thanks Learmec
Is my vette stock?? HAHA
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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Do you have a vacuum pump with a gauge on it. You should vacuum test each part and hose separately and compare that to the good side. It’s obviously a slow leak on the passenger side, you just need to test each part to find it. For the regulator just compare the vacuum readings and watch the gauge to see if it leaks down slowly. Test the hoses separately to eliminate them as an issue and when you put them back on make sure they have a tight seal.
Last edited by Rescue Rogers; Jun 29, 2020 at 09:28 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
Since the problem is just on one lamp, the likely fault lies with the vacuum relay. Bad/leaky seal on shuttle valve inside. Not repairable unless you are a mechanical whiz-bang.
You can prove/disprove this theory by removing the yellow-striped hose from the center fitting on that relay and plumbing it directly to one of the actuator can fittings and then to the other one. One side will open the headlamp bucket; the other side will close it. If that test shows quick open/close of the bucket, the relay IS the problem. If you get the exact same results as you get with it plumbed correctly, then the bucket actuator needs new seal set or replace actuator.
You can prove/disprove this theory by removing the yellow-striped hose from the center fitting on that relay and plumbing it directly to one of the actuator can fittings and then to the other one. One side will open the headlamp bucket; the other side will close it. If that test shows quick open/close of the bucket, the relay IS the problem. If you get the exact same results as you get with it plumbed correctly, then the bucket actuator needs new seal set or replace actuator.
Last edited by 7T1vette; Jun 29, 2020 at 09:43 AM.
Instructor
Joined: Jul 2012
Posts: 171
Likes: 22
From: Kentucky
Since the problem is just on one lamp, the likely fault lies with the vacuum relay. Bad/leaky seal on shuttle valve inside. Not repairable unless you are a mechanical whiz-bang.
You can prove/disprove this theory by removing the yellow-striped hose from the center fitting on that relay and plumbing it directly to one of the actuator can fittings and then to the other one. One side will open the headlamp bucket; the other side will close it. If that test shows quick open/close of the bucket, the relay IS the problem. If you get the exact same results as you get with it plumbed correctly, then the bucket actuator needs new seal set or replace actuator.
You can prove/disprove this theory by removing the yellow-striped hose from the center fitting on that relay and plumbing it directly to one of the actuator can fittings and then to the other one. One side will open the headlamp bucket; the other side will close it. If that test shows quick open/close of the bucket, the relay IS the problem. If you get the exact same results as you get with it plumbed correctly, then the bucket actuator needs new seal set or replace actuator.
Race Director
Joined: Jul 2015
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From: SW Florida.
best first start is shorten every vacuum hose about 3/8ths inch. you have about 20 small vacuum leaks in that car if the hoses are all 40 years old. those you can't cut cuz they are too short? do what you can and see what improvement you get.
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
I'm of the "if it ain't broke...don't fix it" clan. Hoses get hard over the years, and some are darned difficult to get off without slitting them. If they look well attached and not cracked, leave well enough alone. If the attached end of a hose look "iffy", cut a bit off and re-attach.
