How Your Headlight Vacuum System Works
#41
Racer
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tristan69:
The first thing I would try is to run a vacuum hose directly from the check valve's smaller port (on the side with the 2 ports) to the top port (the small one) on the vacuum relay for the wiper door. With apologies to Willcox Corvette for using their excellent on-line vacuum connection diagrams, the wiggly blue line in this image is where I would run the hose:
Be sure to block off the open ends of hoses you disconnect.
Go for a drive.
If the wiper door stays down, then your problem is in one of the hoses or one of the components (circled in green) you have bypassed. If the door does not stay down, test the relay, the actuator, and the related connecting hoses for leaks. My original post in this thread has a link to tests you can perform those components.
Since my 78 doesn't have a wiper door, I can't test this approach on my car. Nor can I tell you how to test the valve in the upper left corner of the diagram or the green-circled component (switch?) near the right side of the diagram. So if the approach I've outlined here doesn't locate your problem, post another entry and maybe someone with wiper door vacuum system experience will chime in.
Good luck!
Jerry
The first thing I would try is to run a vacuum hose directly from the check valve's smaller port (on the side with the 2 ports) to the top port (the small one) on the vacuum relay for the wiper door. With apologies to Willcox Corvette for using their excellent on-line vacuum connection diagrams, the wiggly blue line in this image is where I would run the hose:
Be sure to block off the open ends of hoses you disconnect.
Go for a drive.
If the wiper door stays down, then your problem is in one of the hoses or one of the components (circled in green) you have bypassed. If the door does not stay down, test the relay, the actuator, and the related connecting hoses for leaks. My original post in this thread has a link to tests you can perform those components.
Since my 78 doesn't have a wiper door, I can't test this approach on my car. Nor can I tell you how to test the valve in the upper left corner of the diagram or the green-circled component (switch?) near the right side of the diagram. So if the approach I've outlined here doesn't locate your problem, post another entry and maybe someone with wiper door vacuum system experience will chime in.
Good luck!
Jerry
#42
Instructor
All the vacuum hoses in my 70 are original, I know because I've owned it for 40 years and never replaced anything. My headlights and wiper door are not functioning properly so I suppose it's time to go through the whole system. I know Mid-America and other suppliers sell hose kits. Is there a preferred vendor for such parts. I know when I redid my whole suspension a few years ago, Van Steel and Baer were the ones to go to for parts and rebuild services. How about hoses, actuators, etc?
Thanks
Thanks
#43
Burning Brakes
I think the last thing I would replace on the system would be the hoses. Get your self a Mityvac and test the actuators and the relays first. Make sure these components work properly, if not then the new hoses will be all for naught. If you are concerned about original hoses sealing, you can always trim off a small bit on each open end to take away the 40 year old flare. You can also check each seal on each end of the hoses by connecting one end to a component, and hooking up the Mityvac to the other end of the hose when you test. I happen to like the look of original cleaned up hoses.
#44
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I think I also remember someone reporting the Zip's hoses were difficult to use because the outside diameters were larger than original equipment."
I sincerely apologize to Zip and to all of you great forum members for passing on some bad hearsay, and I promise to do my best to NOT do it again.
For hardware, I have no experience other than recalling some have not had good luck with some reproduction items; and some have suggested using OEM items, but they are pricey if you can find them. When you find a part that needs to be replaced, do a search on this forum specifically for that part. You might find experiences others have reported.
Sorry I can't be more helpful. Hopefully, others will chime in with more info for you.
Last edited by 78IndyPace; 02-25-2011 at 08:25 AM. Reason: Corrected bad information about Zip's hoses.
#46
Jerry, I recently replaced all my vacuum lines and my headlights work great and so does the wiper door.....that is until about 5-10 minutes later the wiper door will raise. WTF
I have my car in the shop for re-painting but want to fix this as soon as it comes out. I was going to clamp of the vacuum supply to the wiper door and see if I can hold the door down. If this works I would move the clamp further from the door until I find the leak.
Do you think this will work or do you suggest a better method.
All the best and once again thanks.
I have my car in the shop for re-painting but want to fix this as soon as it comes out. I was going to clamp of the vacuum supply to the wiper door and see if I can hold the door down. If this works I would move the clamp further from the door until I find the leak.
Do you think this will work or do you suggest a better method.
All the best and once again thanks.
#49
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The article on Corvette-101.com is fixed
Where is the best deal to get the complete hose kit for this application. Dr Rebuild want $50 for the kit and I think that is too, too high. Any suggestions?
BTW: I'm not connected with Willcox in any way.
#50
Instructor
Wow!
If you decided to, you could become the Bill Gates of Tech Writing for anything on earth that's technical.
Do a background check on anybody that asks you to explain nuclear weapons to them!
J/K
-jim
If you decided to, you could become the Bill Gates of Tech Writing for anything on earth that's technical.
Do a background check on anybody that asks you to explain nuclear weapons to them!
J/K
-jim
#51
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...you could become the Bill Gates of Tech Writing...
...check on anybody that asks you to explain nuclear weapons...
#52
Platinum Supporting Vendor
There are no preferred vendors that I know of. I do remember reading that Doc Rebuild's hose kits worked OK. I think I also remember someone reporting the Zip's hoses were difficult to use because the outside diameters were larger than original equipment. (Anyone: Please correct me if I'm wrong and I'll edit this post accordingly.)
For hardware, I have no experience other than recalling some have not had good luck with some reproduction items; and some have suggested using OEM items, but they are pricey if you can find them. When you find a part that needs to be replaced, do a search on this forum specifically for that part. You might find experiences others have reported.
Sorry I can't be more helpful. Hopefully, others will chime in with more info for you.
For hardware, I have no experience other than recalling some have not had good luck with some reproduction items; and some have suggested using OEM items, but they are pricey if you can find them. When you find a part that needs to be replaced, do a search on this forum specifically for that part. You might find experiences others have reported.
Sorry I can't be more helpful. Hopefully, others will chime in with more info for you.
Justin
#53
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C3 of Year Finalist (appearance mods) 2019
My 2 cents worth!
I've installed vacuum hoses from Zip and other vendors and Zip's work just fine! That BS that Zip's hoses have a larger OD and therefore won't fit is just BS.
On the headlight relay the red, yellow and green are a tight fit, but they do fit.
On the headlight relay the red, yellow and green are a tight fit, but they do fit.
#54
Platinum Supporting Vendor
The red, yellow and green are not supposed to be lined up. Here is a pic off a very original 71. You will notice where the plastic is faded and where it is still looks new. That is where the hoses were originally.
[IMG][/IMG]
[IMG][/IMG]
#55
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Posted above by Zip Corvette:
Thanks to you and petes74ttop for setting me straight. I have edited my post (#44 above) accordingly.
My sincere apologies to Zip and to the best Corvette forum on the web for passing on some bad hearsay. That was not fair to Zip, and I promise to do my best NOT to do it again.
Jerry
78IndyPace
If you compare them to a 68 car then yes our hoses are larger, our hoses match the 69L and up. They still work fine and they are on hundreds and hundreds if not thousands of cars. This is something that he said on his website and like I said is taken out of context.
My sincere apologies to Zip and to the best Corvette forum on the web for passing on some bad hearsay. That was not fair to Zip, and I promise to do my best NOT to do it again.
Jerry
78IndyPace
#56
Instructor
I have chased all of the hoses, replaced the switch in the dash. When I hook up the system, the lights pop up (nice and crisp) but never go down. To manually make them go down, I have to disconnect the hose that runs between the check valve and the tank, disconnecting that hose, and pull down the headlights manually.
I have replaced one of the relays that had a broken nipple with a new one. Could the other be bad and if so, could a faulty relay cause this type of symptom?
Thanks...
I have replaced one of the relays that had a broken nipple with a new one. Could the other be bad and if so, could a faulty relay cause this type of symptom?
Thanks...
#57
Instructor
One more question. What is considered the top of the actuator and what is considered the bottom? Which color hose connects to which wide of the actuator?
I realize I've probably just embarrassed myself. There is a certain feeling of freedom since I have also come to realize that it won't be my last time.... ;-)
I realize I've probably just embarrassed myself. There is a certain feeling of freedom since I have also come to realize that it won't be my last time.... ;-)
#58
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Look at Post #1
The relay gets 4 hoses-
Top (Metal) gets White
Next (Plastic) Red
Next (Plastic) Yellow
Next (Plastic) Green
The Actuators-
Red from relay-goes to rear
Green from relay goes to front
For your problem- With the headlight switch off, and Override switch UP do you get vacuum to the TOP (metal) on your relay?
The relay gets 4 hoses-
Top (Metal) gets White
Next (Plastic) Red
Next (Plastic) Yellow
Next (Plastic) Green
The Actuators-
Red from relay-goes to rear
Green from relay goes to front
For your problem- With the headlight switch off, and Override switch UP do you get vacuum to the TOP (metal) on your relay?
#59
Platinum Supporting Vendor
Posted above by Zip Corvette:
Thanks to you and petes74ttop for setting me straight. I have edited my post (#44 above) accordingly.
My sincere apologies to Zip and to the best Corvette forum on the web for passing on some bad hearsay. That was not fair to Zip, and I promise to do my best NOT to do it again.
Jerry
78IndyPace
Thanks to you and petes74ttop for setting me straight. I have edited my post (#44 above) accordingly.
My sincere apologies to Zip and to the best Corvette forum on the web for passing on some bad hearsay. That was not fair to Zip, and I promise to do my best NOT to do it again.
Jerry
78IndyPace
No issues, just setting the story straight.