Headlight switch vacuum and other leaks
01-25-2017, 06:09 PM
#1
Burning Brakes
Thread Starter
Headlight switch vacuum and other leaks
My car randomly stared idling rough a year ago and I tried checking everything. Than a couple weeks ago I drove it for first time with Windows up, the t tops on and the headlights on cause it was cold.
I ended up hearing a vacuum leak at my Headlight switch, which only occurs when I have the lights on. I read on here that the hoses could be switched but does it only happen when the switch is on the on position? The headlights go up and down as normal. Could this leak be enough to effect idle?
my other leak is the wiper door. A year ago or so I really worked all the vacuum lines and parts and fixed several issues. The only thing I had left was that when I stared the car, the wiper door would go from closed ton open for about 5 seconds and than close again. It would stay closed until I started car next time. On the same trip home from shop the door stopped responding and just stays half way open. The override doesn't have any effect either. I'm getting motivated to do another run through the vacuum system and wondered if anyone could suggest what to check first for the door. FYI I have already replaced the 3 valves for headlights and door.
Thanks Jim
69 corvette w ac
I ended up hearing a vacuum leak at my Headlight switch, which only occurs when I have the lights on. I read on here that the hoses could be switched but does it only happen when the switch is on the on position? The headlights go up and down as normal. Could this leak be enough to effect idle?
my other leak is the wiper door. A year ago or so I really worked all the vacuum lines and parts and fixed several issues. The only thing I had left was that when I stared the car, the wiper door would go from closed ton open for about 5 seconds and than close again. It would stay closed until I started car next time. On the same trip home from shop the door stopped responding and just stays half way open. The override doesn't have any effect either. I'm getting motivated to do another run through the vacuum system and wondered if anyone could suggest what to check first for the door. FYI I have already replaced the 3 valves for headlights and door.
Thanks Jim
69 corvette w ac
Last edited by xpoc454; 01-25-2017 at 06:10 PM.
01-25-2017, 06:43 PM
#2
Safety Car
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Jim,
Welcome to the musical chairs of vacuum.
I went through this same stuff with my 68 BB w/A/C for about a year.
Assuming the replacement parts are good, you have to isolate each system and test.
Yes, I believe a vac leak any where is going to transfer back to the engines idle quality.
If the vac was not drawn from the engine ie... vac pump it would not effect the engine idle.
I separated the wiper system and tested everything. Then did the head light side same way testing and replacing as needed, then the HVAC lines. Leaks do not discriminate. They can be in any or all of the 3 vac systems in our cars.
In the end I installed a NOS head lamp switch which still leaks a little.
I'm not pulling the dash apart again at this point.
When I start my car in thee morning after about 15-30 seconds the wiper door opens, followed by the right side head light then the left.
It always opens in that order and never deviates. It like watching the Glockenspiel in Munich.
Then after about 20 seconds the right side head light drops with authority followed by the left side and lastly the wiper door.
Then the right side kick panel fresh air door closes smartly.
Again always in this order. The wiper/ headlightss will remain down after driving and stopping and restarting while out on a day trip or attending a cruise nite etc.
They will not last more than 6 hours without going through this same ritual.
I'm ok at this point with this level of operation.
They work when I need them now and that's a huge improvement.
It felt like eternity to get to this point.
I had a bad head light actuator from Ebay.
I tested everything else and still had issues.
Getting ready to pull my hair out and found a ruptured diaphragm inside an off shore made head light actuator.
So I bought another set used take offs.
Had 2 new relays rebuilt by a forum member here thanks Dave!
And hours of trouble shooting just to get them to work as designed with a reserve time of about 6 hours. I believe at this point this is the best I can get out of her.
Miti Vac works wonders to trouble shoot. Do not use compressed air you will blow the diaphragm's out.
Others will chime in as this has been a hotbed of conversation on this forum.
Stay at it you'll get it.
Marshal
Welcome to the musical chairs of vacuum.
I went through this same stuff with my 68 BB w/A/C for about a year.
Assuming the replacement parts are good, you have to isolate each system and test.
Yes, I believe a vac leak any where is going to transfer back to the engines idle quality.
If the vac was not drawn from the engine ie... vac pump it would not effect the engine idle.
I separated the wiper system and tested everything. Then did the head light side same way testing and replacing as needed, then the HVAC lines. Leaks do not discriminate. They can be in any or all of the 3 vac systems in our cars.
In the end I installed a NOS head lamp switch which still leaks a little.
I'm not pulling the dash apart again at this point.
When I start my car in thee morning after about 15-30 seconds the wiper door opens, followed by the right side head light then the left.
It always opens in that order and never deviates. It like watching the Glockenspiel in Munich.
Then after about 20 seconds the right side head light drops with authority followed by the left side and lastly the wiper door.
Then the right side kick panel fresh air door closes smartly.
Again always in this order. The wiper/ headlightss will remain down after driving and stopping and restarting while out on a day trip or attending a cruise nite etc.
They will not last more than 6 hours without going through this same ritual.
I'm ok at this point with this level of operation.
They work when I need them now and that's a huge improvement.
It felt like eternity to get to this point.
I had a bad head light actuator from Ebay.
I tested everything else and still had issues.
Getting ready to pull my hair out and found a ruptured diaphragm inside an off shore made head light actuator.
So I bought another set used take offs.
Had 2 new relays rebuilt by a forum member here thanks Dave!
And hours of trouble shooting just to get them to work as designed with a reserve time of about 6 hours. I believe at this point this is the best I can get out of her.
Miti Vac works wonders to trouble shoot. Do not use compressed air you will blow the diaphragm's out.
Others will chime in as this has been a hotbed of conversation on this forum.
Stay at it you'll get it.
Marshal
01-25-2017, 07:27 PM
#3
Race Director
The new actuator relays are what is causing the wiper door and headlights to open when you crank the car up...and THAT is also if the rest of the vacuum system is PERFECT.
As stated by 'marshal135' and I agree...ANY vacuum leaks are not good.
I do not know what else to say to you due to not knowing what your plans are....but I will add this. When I do tune-ups on the Corvettes with all the vacuum stuff on them...I delete them off the intake fitting and tune the engine WITHOUT them attached. So I can get the engine running correctly. Then ...when I connect the vacuum hose back up to the intake fitting.....and the engine begins to run rough. I can show the owner that it IS NOT my tune up....it is other stuff that needs to be corrected.
DUB
As stated by 'marshal135' and I agree...ANY vacuum leaks are not good.
I do not know what else to say to you due to not knowing what your plans are....but I will add this. When I do tune-ups on the Corvettes with all the vacuum stuff on them...I delete them off the intake fitting and tune the engine WITHOUT them attached. So I can get the engine running correctly. Then ...when I connect the vacuum hose back up to the intake fitting.....and the engine begins to run rough. I can show the owner that it IS NOT my tune up....it is other stuff that needs to be corrected.
DUB
The following 2 users liked this post by DUB:
64roadster (01-27-2017),
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01-25-2017, 10:01 PM
#4
Burning Brakes
I read on here that the hoses could be switched? The headlights go up and down as normal.
I ended up hearing a vacuum leak at my Headlight switch, which only occurs when I have the lights on.
The only thing I had left was that when I stared the car, the wiper door would go from closed ton open for about 5 seconds and than close again.
The most common culprit in this case is the valve located beneath the passenger windshield wiper base. Notorious for leaking. In your case, it could be this valve, the headlight switch valve, or both.
Like Marshall said, a Mityvac can do wonders diagnosing trouble, do you have one?
01-25-2017, 10:23 PM
#5
Safety Car
One other suggestion, I always isolate the wiper door or headlights when working on the vacuum system so I can fix one problem at a time. Plug the wiper vacuum line and get the headlights working correctly, than you can chase the leaks in the wiper door system.
01-25-2017, 10:46 PM
#6
Safety Car
If your headlights work up and down as normal, your headlight switch hoses are connected properly. If the hoses were switched, they would not.
It is normal to have a vacuum loss @ the switch for only a second or so. That is the sound of atmosphere rushing back into the vacuum hose from the relays to the switch at the valve. If you hear a constant leak, you have another issue, likely a leaking headlight switch vacuum valve.
This is most commonly caused by an imbalance between the control and actuating sides of the vacuum system. What happens is if the actuators and relays are relative leak free, and the control hose is leaking (headlight switch valve in your case), there is not enough vacuum @ startup to keep the relay internal piston in position to direct vacuum to the closing side of the actuator. Eventually, the control vacuum to the relay catches up and closes the door.
The most common culprit in this case is the valve located beneath the passenger windshield wiper base. Notorious for leaking. In your case, it could be this valve, the headlight switch valve, or both.
Like Marshall said, a Mityvac can do wonders diagnosing trouble, do you have one?
It is normal to have a vacuum loss @ the switch for only a second or so. That is the sound of atmosphere rushing back into the vacuum hose from the relays to the switch at the valve. If you hear a constant leak, you have another issue, likely a leaking headlight switch vacuum valve.
This is most commonly caused by an imbalance between the control and actuating sides of the vacuum system. What happens is if the actuators and relays are relative leak free, and the control hose is leaking (headlight switch valve in your case), there is not enough vacuum @ startup to keep the relay internal piston in position to direct vacuum to the closing side of the actuator. Eventually, the control vacuum to the relay catches up and closes the door.
The most common culprit in this case is the valve located beneath the passenger windshield wiper base. Notorious for leaking. In your case, it could be this valve, the headlight switch valve, or both.
Like Marshall said, a Mityvac can do wonders diagnosing trouble, do you have one?
I just posted yesterday about the new aftermarket headlight/wiper door vacuum relays. I found that the internal spring holding the relay diaphragm in the open position until over powered by vacuum is too strong creating a delay and allowing the door to partially open and close on startup. I found the original relays need only about 1" of control vacuum to overpower the diaphragm spring and move the internal valve to the closed position where the new repops need about 3". Since the wiper door actuator only needs about half that to operate the door moves momentarily until the spring is overpowered, unlike the originals. Do you know of anyone producing relays that work as they were originally intended? Thanks.
Grant
Last edited by CanadaGrant; 01-25-2017 at 11:21 PM.
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marshal135 (01-30-2017)
01-25-2017, 11:36 PM
#7
Burning Brakes
Grant,
I saw your post about the repop relays, and the spring pressure issue. I must admit, I'm having a difficult time coming to grips with this conclusion. Not that I am doubting your reasoning, I cannot duplicate this issue on my mock-up vacuum component system. I can duplicate the "winking" wiper door issue by simulating a leak in the control side in any one of the control components. It could be in your case that the small difference in GM vs Chinese relay spring rates could be the overcoming the difference between a leaking control side and a vacuum tight actuator side. I simply need more time to test this.
I will also admit, I do not have much desire to play around with the repop relays. The reasoning is simple. My method of rebuilding the GM relays works so well there is no reason for me or my friends to even consider using them. The tight tolerances in the GM relay bodies lends them to take my machined pistons very well, while the repop relays internal tolerances are so all over the place I would have to machine each one individually.
If you're interested, I would rebuild your original GM relays for you. They will work as you describe. Just let me know.
I saw your post about the repop relays, and the spring pressure issue. I must admit, I'm having a difficult time coming to grips with this conclusion. Not that I am doubting your reasoning, I cannot duplicate this issue on my mock-up vacuum component system. I can duplicate the "winking" wiper door issue by simulating a leak in the control side in any one of the control components. It could be in your case that the small difference in GM vs Chinese relay spring rates could be the overcoming the difference between a leaking control side and a vacuum tight actuator side. I simply need more time to test this.
I will also admit, I do not have much desire to play around with the repop relays. The reasoning is simple. My method of rebuilding the GM relays works so well there is no reason for me or my friends to even consider using them. The tight tolerances in the GM relay bodies lends them to take my machined pistons very well, while the repop relays internal tolerances are so all over the place I would have to machine each one individually.
Do you know of anyone producing relays that work as they were originally intended?
The following 2 users liked this post by Dave J:
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01-26-2017, 12:21 AM
#8
Instructor
The new actuator relays are what is causing the wiper door and headlights to open when you crank the car up...and THAT is also if the rest of the vacuum system is PERFECT.
As stated by 'marshal135' and I agree...ANY vacuum leaks are not good.
I do not know what else to say to you due to not knowing what your plans are....but I will add this. When I do tune-ups on the Corvettes with all the vacuum stuff on them...I delete them off the intake fitting and tune the engine WITHOUT them attached. So I can get the engine running correctly. Then ...when I connect the vacuum hose back up to the intake fitting.....and the engine begins to run rough. I can show the owner that it IS NOT my tune up....it is other stuff that needs to be corrected.
DUB
As stated by 'marshal135' and I agree...ANY vacuum leaks are not good.
I do not know what else to say to you due to not knowing what your plans are....but I will add this. When I do tune-ups on the Corvettes with all the vacuum stuff on them...I delete them off the intake fitting and tune the engine WITHOUT them attached. So I can get the engine running correctly. Then ...when I connect the vacuum hose back up to the intake fitting.....and the engine begins to run rough. I can show the owner that it IS NOT my tune up....it is other stuff that needs to be corrected.
DUB
I'm taking that on board, didn't even give it a second thought but makes perfect sense.
01-26-2017, 07:50 AM
#9
Burning Brakes
Thread Starter
Okay, let me clarify what is going on just to not confuse anyone.
My headlights work perfectly fine. They do not come up unless I use the headlight switch or override switch. Im pretty happy with them right now.
What I do hear, is a constant vacuum sound right at the switch, only when I pull the headlight switch to the on position.
I have replaced all 3 vacuum relays a couple years ago and they all worked perfectly. These are the 2 that are near headlights and on my car the one in the passenger fender well.
The wiper door 'used' to pop up at startup and than go down after 5 seconds. But since I brought it back from the shop, it pops up and does not respond.
The first thing I want to check is if hearing a vacuum all the time at the headlight switch is normal when in the on position and what could possibly be causing this. If this is an unusual sitution, im going to open up the dash and get to the switch and see where and why it is making a vacuum sound.
Than I will go to the wiper door and check the relay and anything else anyone could suggest.
thanks
jim
My headlights work perfectly fine. They do not come up unless I use the headlight switch or override switch. Im pretty happy with them right now.
What I do hear, is a constant vacuum sound right at the switch, only when I pull the headlight switch to the on position.
I have replaced all 3 vacuum relays a couple years ago and they all worked perfectly. These are the 2 that are near headlights and on my car the one in the passenger fender well.
The wiper door 'used' to pop up at startup and than go down after 5 seconds. But since I brought it back from the shop, it pops up and does not respond.
The first thing I want to check is if hearing a vacuum all the time at the headlight switch is normal when in the on position and what could possibly be causing this. If this is an unusual sitution, im going to open up the dash and get to the switch and see where and why it is making a vacuum sound.
Than I will go to the wiper door and check the relay and anything else anyone could suggest.
thanks
jim
Last edited by xpoc454; 01-26-2017 at 07:52 AM.
01-26-2017, 08:33 AM
#10
Safety Car
Member Since: Sep 2011
Location: Madeira Beach, FL
Posts: 3,563
Received 797 Likes
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2023 C2 of the Year Finalist - Unmodified
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Jim,
It sounds like you are in the same boat as I am.
The head light switch as Dave stated should hiss momentarily as the atmospheric pressure rushes in to fill the void the vacuum had created.
A negative pressure keeps the control side charged so to speak.
If the control side, small black lines with a white skunk stripe, is tight technically you could come outside the next morning start the car and see no movement in any of the components.
The wiper door is affected first when the control side leaks down.
My wiper door is the first to move and last to close.
I purchased a new old stock head lamp switch and it is better than what I took off but still leaks down.
I wish there was someone who rebuilds these???? Dave
If I could get the switch 100%, I then could go through the HVAC side and test all the components and replace as needed which I believe would restore the system to a near new condition.
As Alan has shared with us since he owned his car since new, the headlamps should cycle one time up/down with the reserve vacuum in the canister on the firewall behind the master cylinder. This is a bugger to get out. New they were tight for a day.
There are ways to test the head lamp switch with out removing it.
Dave and DUB have the best method hopefully they can provide the details as I forget and don't want to provide bum scoop.
Marshal
It sounds like you are in the same boat as I am.
The head light switch as Dave stated should hiss momentarily as the atmospheric pressure rushes in to fill the void the vacuum had created.
A negative pressure keeps the control side charged so to speak.
If the control side, small black lines with a white skunk stripe, is tight technically you could come outside the next morning start the car and see no movement in any of the components.
The wiper door is affected first when the control side leaks down.
My wiper door is the first to move and last to close.
I purchased a new old stock head lamp switch and it is better than what I took off but still leaks down.
I wish there was someone who rebuilds these???? Dave
If I could get the switch 100%, I then could go through the HVAC side and test all the components and replace as needed which I believe would restore the system to a near new condition.
As Alan has shared with us since he owned his car since new, the headlamps should cycle one time up/down with the reserve vacuum in the canister on the firewall behind the master cylinder. This is a bugger to get out. New they were tight for a day.
There are ways to test the head lamp switch with out removing it.
Dave and DUB have the best method hopefully they can provide the details as I forget and don't want to provide bum scoop.
Marshal
01-26-2017, 07:35 PM
#11
Race Director
Hi Dave,
I just posted yesterday about the new aftermarket headlight/wiper door vacuum relays. I found that the internal spring holding the relay diaphragm in the open position until over powered by vacuum is too strong creating a delay and allowing the door to partially open and close on startup. I found the original relays need only about 1" of control vacuum to overpower the diaphragm spring and move the internal valve to the closed position where the new repops need about 3". Since the wiper door actuator only needs about half that to operate the door moves momentarily until the spring is overpowered, unlike the originals. Do you know of anyone producing relays that work as they were originally intended? Thanks.
Grant
I just posted yesterday about the new aftermarket headlight/wiper door vacuum relays. I found that the internal spring holding the relay diaphragm in the open position until over powered by vacuum is too strong creating a delay and allowing the door to partially open and close on startup. I found the original relays need only about 1" of control vacuum to overpower the diaphragm spring and move the internal valve to the closed position where the new repops need about 3". Since the wiper door actuator only needs about half that to operate the door moves momentarily until the spring is overpowered, unlike the originals. Do you know of anyone producing relays that work as they were originally intended? Thanks.
Grant
https://www.corvetteforum.com/forums...t-problem.html
AS for someone who is reproducing the actuator relays to correct standards..I have NO CLUE. But I have found a way to 100% stop this from happening.
DUB
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CanadaGrant (01-26-2017)
01-26-2017, 11:58 PM
#12
Safety Car
Check this out.
https://www.corvetteforum.com/forums...t-problem.html
AS for someone who is reproducing the actuator relays to correct standards..I have NO CLUE. But I have found a way to 100% stop this from happening.
DUB
https://www.corvetteforum.com/forums...t-problem.html
AS for someone who is reproducing the actuator relays to correct standards..I have NO CLUE. But I have found a way to 100% stop this from happening.
DUB
How did you stop yours from doing this?
I fooled with it and found that if I used a 1" long piece of fine tube like the hard plastic tube that comes with carb cleaner or PB Blaster and slide it between the inlet tube "open" side of the wiper door actuator and the vacuum hose to make a very small controlled leak it completely cured the problem. That side is vented normally anyway so there is no controlled leak unless the relay valve goes to open.
Thanks again!
Grant
Last edited by CanadaGrant; 01-27-2017 at 12:31 AM.
01-27-2017, 12:56 AM
#13
Safety Car
Okay, let me clarify what is going on just to not confuse anyone.
My headlights work perfectly fine. They do not come up unless I use the headlight switch or override switch. Im pretty happy with them right now.
What I do hear, is a constant vacuum sound right at the switch, only when I pull the headlight switch to the on position.
I have replaced all 3 vacuum relays a couple years ago and they all worked perfectly. These are the 2 that are near headlights and on my car the one in the passenger fender well.
The wiper door 'used' to pop up at startup and than go down after 5 seconds. But since I brought it back from the shop, it pops up and does not respond.
The first thing I want to check is if hearing a vacuum all the time at the headlight switch is normal when in the on position and what could possibly be causing this. If this is an unusual sitution, im going to open up the dash and get to the switch and see where and why it is making a vacuum sound.
Than I will go to the wiper door and check the relay and anything else anyone could suggest.
thanks
jim
My headlights work perfectly fine. They do not come up unless I use the headlight switch or override switch. Im pretty happy with them right now.
What I do hear, is a constant vacuum sound right at the switch, only when I pull the headlight switch to the on position.
I have replaced all 3 vacuum relays a couple years ago and they all worked perfectly. These are the 2 that are near headlights and on my car the one in the passenger fender well.
The wiper door 'used' to pop up at startup and than go down after 5 seconds. But since I brought it back from the shop, it pops up and does not respond.
The first thing I want to check is if hearing a vacuum all the time at the headlight switch is normal when in the on position and what could possibly be causing this. If this is an unusual sitution, im going to open up the dash and get to the switch and see where and why it is making a vacuum sound.
Than I will go to the wiper door and check the relay and anything else anyone could suggest.
thanks
jim
Last edited by CanadaGrant; 01-27-2017 at 12:58 AM.
01-27-2017, 05:41 PM
#14
Race Director
Thanks a bunch DUB! I tested that relay every which way till the cows came home and it didn't leak anywhere. Tested perfect until I checked to see how much vacuum it took to overpower the spring to put the valve in the closed position. The stock one was just over 1" and aftermarket was 3"HG so when it only takes around 11/2" to move the wiper door it momentarily rises then falls on start and again on vacuum bleed off after shut down. Wish I had seen your post last year.... My original one works great but I bought the aftermarket one for the "new shine" just to spruce things up. It came from Corvette Central but who knows where they got it. I got one of the new type wiper door safety switches from Willcox that works great so between all the faulty ones and these garbage relays it's a wonder anybody's door works like it should.
How did you stop yours from doing this?
I fooled with it and found that if I used a 1" long piece of fine tube like the hard plastic tube that comes with carb cleaner or PB Blaster and slide it between the inlet tube "open" side of the wiper door actuator and the vacuum hose to make a very small controlled leak it completely cured the problem. That side is vented normally anyway so there is no controlled leak unless the relay valve goes to open.
Thanks again!
Grant
How did you stop yours from doing this?
I fooled with it and found that if I used a 1" long piece of fine tube like the hard plastic tube that comes with carb cleaner or PB Blaster and slide it between the inlet tube "open" side of the wiper door actuator and the vacuum hose to make a very small controlled leak it completely cured the problem. That side is vented normally anyway so there is no controlled leak unless the relay valve goes to open.
Thanks again!
Grant
I spent quite a bit of time figuring out the problem..and to be honest. I get paid to fix this issue when the Corvettes have this problem when they come into my shop....so putting it out on the internet is just not going to happen.
I will say that my method does not require a controlled vacuum leak. The system is factory correct in all aspects. You could not find what I did to fix it by looking at it.
I will say you are a person who thinks...so...if you are happy with your method...GREAT! Leave well enough alone. But if not stop adn thinka about it some more. You are so close.
DUB