Headlight vacuum help
- Thread starter jdnathan
- Start date
antijam
CCCUK Member
The problem you're experiencing is a not uncommon one. The Corvette vacuum system is fairly complex, involving not just actuation but switching and sequencing operations too, and short of outright failure, it can be difficult to diagnose the specific problem component.
On these older cars vacuum leaks are common, both in the vacuum tank and in the hoses, actuators can bind up as can the headlamp vacuum relays.
The operation of the lights shouldn't be particularly slow but even with everything in good working order both lights rarely operate simultaneously - there's no mechanical connection between them, only rather squishy vacuum.
I had your problem and it was vastly improved by replacing all the vacuum rubber lines. This is a tedious but not difficult job; it worked for me but there's no guarantee it'll sort your problem.
On these older cars vacuum leaks are common, both in the vacuum tank and in the hoses, actuators can bind up as can the headlamp vacuum relays.
The operation of the lights shouldn't be particularly slow but even with everything in good working order both lights rarely operate simultaneously - there's no mechanical connection between them, only rather squishy vacuum.
I had your problem and it was vastly improved by replacing all the vacuum rubber lines. This is a tedious but not difficult job; it worked for me but there's no guarantee it'll sort your problem.
Roscobbc
Moderator
The rubber vacuum lines will tend to crack and perish over time.......problem being difficultly identifying where a leak may be (needing to have the engine running)......perhaps an old squeegy bottle filled with water with an spray/atomiser head directed at sections of the vacuum tubing would give a clue. If the vacuum tank is in good order (and capable of holding a vacuum for a few minutes) it might allow you to turn the engine off and listen for a possible vacuum leak?
johng
CCCUK Member
A hand vacuum pump like this will let you test the individual bits of the system.
https://www.amazon.co.uk/DHA-Bleedi...8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1
https://www.amazon.co.uk/DHA-Bleedi...8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1
Chuffer
CCCUK Member
I had the same issues too . I bought the very same vacuum pump kit that johng has pointed out . Inexpensive and very useful . In my case the vacuum loss was down to warn seals on the actuators . Replacement kits are available from UK Corvette specialists and not expensive and the strip down and rebuild with new seals is straight forward . The real faff is unbolting and easing out the actuator bodies through a tight space . As Antijam said , you will still probably have one raise before the other as vacuum is gradually created throughout the system but should at least be quite quick once all leaks have been cured .
Roscobbc
Moderator
Remember also that if your engine has an aftermarket camshaft the engine will often have a reduced vacuum signal.......just makes the vacuum reservoir more important and having a little bit of patience waiting for it to 'charge' up and for the headlamps to open (and wiper flap on earlier C3's.
CaptainK
CCCUK Member
I had this on my 1968 C3, so I took the longwinded and possibly silly method of "fixing" it by replacing all the vacuum stuff with electric motors. Yay! No vacuum issues, and a motor on each light operating at the same time will always mean the lights open at the same time, right? Right?
Nope. The passenger one didn't want to really open at all in the new world.
Long story cut very short - get up into the headlight units, clean up the moving parts that are connected to the rod from the vac actuator (or motor in my case now) and then lubricate the heck out of the whole mechanism.
My "slow" issue was primarily because the passenger side was slightly stiff / seized compared to the driver side. I've done as best I can with the units still in the car (access not so great), so ideally it all needs to come out and be disassembled and lubricated properly. Mine now works fine enough for me, but the passenger side is "just" slower than the drivers side. Enough to be noticed, but not enough for me to really care all that much about.
Nope. The passenger one didn't want to really open at all in the new world.
Long story cut very short - get up into the headlight units, clean up the moving parts that are connected to the rod from the vac actuator (or motor in my case now) and then lubricate the heck out of the whole mechanism.
My "slow" issue was primarily because the passenger side was slightly stiff / seized compared to the driver side. I've done as best I can with the units still in the car (access not so great), so ideally it all needs to come out and be disassembled and lubricated properly. Mine now works fine enough for me, but the passenger side is "just" slower than the drivers side. Enough to be noticed, but not enough for me to really care all that much about.
Chuffer
CCCUK Member
jdnathan , Ross made a good point about allowing for a delay in creating vacuum which is done via a connection to the inlet manifold . I don`t know about your C3 model year but on the 1980 there is an inline non return valve and a small inline filter in the last 300mm or so length of hose to the manifold . Worth checking them out too and cleaning / replacing . They are on a few £ and any faults will reduce the ability to create full vacuum . My non return valve didn`t non return and I had no filter at all !!
