My left headlight was slower to open than the right. Since i had changed the rod seal on the right actuator, I figured that if i did the left one than they should both open at about the same time. After completing the rod seal change on the actuator, it takes 20 seconds for the left headlight to open followed by the right one 3-4 seconds later (after pulling headlight switch). When i shut the lights off it also takes about 10 seconds, and then the right headlight closes first follwed by the left. Also when i start the car, the headlights NOW pop up, and i have to pull the headlight switch on and off to close the headlights. I am thinking that when i replaced the rod seal and reinstalled the clevis piece on the end of the rod and tightened it, I may have ripped the actuator by twisting the rod. I also had to adjust the position of the clevis to open completly in order to activate the switch that lets you know if the headlights are not in a seated position. I did have the override switch under the dash pulled down to keep the headlights in the up position when i was manually opening and closing the left headlight. WHAT IS WRONG?? I LOST GROUND. I have read the trouble shooting brochure and still do not know what to start with. I hope this long message is complete. I now have a vacum leak someplace as my idle is down about 100 rpm
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Re: C3 headlight trouble
It's very possible that the diaphragm inside the actuator ripped when you turned the actuator rod. To find out, remove and plug the hose going to the front of the actuator and start the engine. Put your finger over the nipple on the front of the actuator and feel for airflow or vacuum. Make sure your fingers are not in the way of the headlight mechanism. If airflow is present,the actuator is toast. I know of no practical way of fixing the inner diapragm. Sorry. -
Re: C3 headlight trouble
If your idle is down you repaired a vacuum leak. More air means a faster idle, not slower.Comment
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Re: C3 headlight trouble
does any body have an idea why the lights come up when i start the car???Comment
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Re: C3 headlight trouble
Jeff,
Although it is not readily apparent, there are two vacuum systems on C3 Corvettes. There is a control system (smaller diameter hoses) and an operating system (larger diameter hoses). The two systems are designed such that when the vacuum comes up the smaller volume control system receives vacuum first. That way the controls are in the desired position as the operating system is evacuated.
If you have a large enough leak in one of the control systems (and you do) it can not receive vacuum before the operating system. The result will be the blinking lights you experience, or the windshield wiper door will wave at the driver on engine start-up if the leak is in the other control system.
Seek out your leaks. Note the use of the plural - there is almost always more than one leak in these often abused and neglected systems.TerryComment
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Re: C3 headlight trouble
The reason is that the headlight actuators are commanded to open when there is no (or not enough) vacuum at the headlight vacuum relay control input. I just fixed this problem in my '72. The cause was a big leak in the vacuum relay and the acuator for the wiper door system, plus a bunch of small leaks elsewhere.
The best approach is to leak check each of the three vacuum relays (I had 2 of 3 leaking) and each of the three actuators at the headlights and wiper door (again, 2 of 3 leaked). Replace all of the vacuum hoses. You will need a $20 vacuum gauge. A vacuum pump really helps also.Comment
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Good Advice!
Well said by both Terry and John! When troubleshooting vac systems, first UNDERSTAND the system (the vac troubleshooting phamphlets do a lot) then do the FULL job. Don't just look for one leak/fault...go through the whole system and verify 'er right on down the pipe!
Next, instead of buying diagnostic equipment like a vac pump, consider the olde Corvette mechanic's 'trick'.... Take a second vehicle (car, truck, Etc.) and park it outside your garage. Get a LONG section of rubber hose and connect to the aux vehicle's intake.
Run the hose inside the garage and CLOSE the door. Use the outside vehicle as a source of vacuum so you can test, check, probe your car in SILENCE! You'll find faults and leak sources appear to LEAP out since you can actually hear air hissing here/there....
Last, don't forget important sections of the vac system are NOT under the hood! Control vac branches at the check valve and one branch runs through the firewall into the cockpit to service heater/AC, wiper and headlight control switches. It wouldn't be the first time a prior 'Bubba' pulled the instrument panel and left vac lines disconnected/mis-connected.Comment
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Also....
once you've read/studied one of the vacuum system troubleshooting phamphlets sold by various catalog houses, you'll understand there's an inherent difference between RH and LH headlights. The vac servo lines (vac that does work moving this/that part) are separate for the two headlights. The RH headlight shares its vac servo line with the wiper door while the LH headlight has its own, dedicated, vac servo line (note wiper door was eliminated in '73).
So, it's not unsual for the two headlights to open/close with 'slightly' different speed. Plus, the RH headlight can exhibit problems that are actually upstream due to vac fault(s) in the wiper door circuitry....
When troubleshooting the vac system, it's VITAL to understand the vac circuit topology! For areas where the system T's and vac routes in parallel, you have to verify one step at a time (disconnect and blind one of the parallel paths while you diagnose the active path, then reverse the process for the opposite side).Comment
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