Too much vacuum?
Thread Starter
Racer
Joined: May 2003
Posts: 432
Likes: 0
From: Manchvegas NH
Too much vacuum?
I hope this one hasn't been asked too many times.
Unlike most headlight vacuum problems, my headlights pop up with gusto. It's closing them that's the problem. When I close them, the passenger side drops almost immediately. The drivers side will stay open for varying amounts of time while driving. Sometimes it will take over an hour until it will finally drop.
I found that I could help it along by pulling the wiper door helper switch under the dash. This will usually make the headlight drop within a minute.
Also, the vacuum will not open the wiper door by itself. I have to give it a helping hand.
Unlike most headlight vacuum problems, my headlights pop up with gusto. It's closing them that's the problem. When I close them, the passenger side drops almost immediately. The drivers side will stay open for varying amounts of time while driving. Sometimes it will take over an hour until it will finally drop.
I found that I could help it along by pulling the wiper door helper switch under the dash. This will usually make the headlight drop within a minute.
Also, the vacuum will not open the wiper door by itself. I have to give it a helping hand.
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
Probably either a bad relay or actuator. Try swapping the relays left to right and see if the problem moves to the pass. side. If so, you've got a bad relay. Cheap fix is to just run both sides off one relay using a coupe T-fittings. If the problem stays on the driver's side, you probably have a bad actuator ... rebuild/replace.
Could be hoses too, but since it's only on one side there's only like 3 (short) hoses that it could be. (the 3 big ones that plug into that side's relay)
Could be hoses too, but since it's only on one side there's only like 3 (short) hoses that it could be. (the 3 big ones that plug into that side's relay)
Last edited by wcsinx; Aug 27, 2004 at 03:24 PM.
Intermediate
Joined: Aug 2004
Posts: 28
Likes: 0
I went through the same issues with my '69. Same one-eyed close issue.
Over the next two years I:
1. Resealed both headlight vacuum canisters.
2. Resealed the headlight door vacuum canister and replaced all of the vacuurm hose.
3. replaced the headlight relay valve.
4. replaced the wiper door relay valve.
at this point the system performed better, but still one eye at a time. And now the wiper door was slower than before. Then I got to tracing the vacuum lines again and discovered a limit vacuum relay under the passenger windshield wiper arm. It looked really nasty and when I removed it, I could see why I was losing vacuum somewhere. Be sure you sit down when you order this from Eckler's or Zip. Pricey....but this solved all of my vacuum issues.
Over the next two years I:
1. Resealed both headlight vacuum canisters.
2. Resealed the headlight door vacuum canister and replaced all of the vacuurm hose.
3. replaced the headlight relay valve.
4. replaced the wiper door relay valve.
at this point the system performed better, but still one eye at a time. And now the wiper door was slower than before. Then I got to tracing the vacuum lines again and discovered a limit vacuum relay under the passenger windshield wiper arm. It looked really nasty and when I removed it, I could see why I was losing vacuum somewhere. Be sure you sit down when you order this from Eckler's or Zip. Pricey....but this solved all of my vacuum issues.
Team Owner
Joined: Jun 2004
Posts: 20,216
Likes: 4
From: Smile, it's just the internet.
Herrelld, Got a picture? This is a vacuum component, not an electrical component? What's it do? What's the Zip P/N..can't find anthing by your description.
(I'm tracking down vacuum demons right now.) (Looking for o-rings to rebuild my relay valves.)
(I'm tracking down vacuum demons right now.) (Looking for o-rings to rebuild my relay valves.)
Intermediate
Joined: Jul 2004
Posts: 38
Likes: 0
yes, when it comes to c3 headlights and wiper doors, the terms actuators and relays refer to vacuum components. There are vacuum relays and acuators for both the wiper door and headlights. The relays determine if it closes or opens and the actuators do the work. easy to check with a hand vacuum pump, try this site for some good info
http://www.corvette-101.com/
http://www.corvette-101.com/
Team Owner
Joined: Jun 2004
Posts: 20,216
Likes: 4
From: Smile, it's just the internet.
Right. I still don't see any mention of this "limit vacuum relay". I've got both of my vacuum relays out and disassembled for repair, so I know exactly what those are. I know there are two controls (essentially limit switches) associated with the wipers to determine when to open and close the door. I know the "open" limit switch is electrical. I just assumed the "close" limit switch was also electrical...I didn't actually look at it, though. Is this the "limit vacuum relay" Herrelld is talking about?
Team Owner
Joined: Jun 2004
Posts: 20,216
Likes: 4
From: Smile, it's just the internet.
After repairing both my vacuum relays (at a total cost of $0.76), I tested the system and found NO leakage. I also took a close look in the wiper cavity and couldn't find anything even remotely related to the vacuum system. Maybe the '68 is different?
Regardless, the headlight and wiper door had erratic motion prior to this repair. Particularly noticiable was the different speed with which the two headlights would drop when turned off. One would drop quickly while other lingered for a moment before dropping slowly.
Now they snap open and closed in unison. the ONLY thing I changed was the relay seals.
Regardless, the headlight and wiper door had erratic motion prior to this repair. Particularly noticiable was the different speed with which the two headlights would drop when turned off. One would drop quickly while other lingered for a moment before dropping slowly.
Now they snap open and closed in unison. the ONLY thing I changed was the relay seals.
Thread Starter
Racer
Joined: May 2003
Posts: 432
Likes: 0
From: Manchvegas NH
Thanks for all the info.
CGGorman, are the relay seals a tough item to replace? Any pointers? Where did you buy the seals?
It sounds like you were having the same exact problem that I'm having.
CGGorman, are the relay seals a tough item to replace? Any pointers? Where did you buy the seals?
It sounds like you were having the same exact problem that I'm having.
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