Wiper door question
Thread Starter
Pro
Joined: Apr 2016
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Wiper door question
The windshield wiper door on my 69 works and all but I have a question, is it normal for it to pop up and then go back down when the car is started? If it's not normal what needs to be done to correct it? This is my first corvette, I'm still trying to learn all the little nuances of them.
Team Owner
Joined: Sep 2006
Posts: 31,202
Likes: 4,287
From: Westminster Maryland
Hi TG,
No, the door should stay closed upon start up.
I wish I could say it's easy to find the cause but it's not.
Do you have a Chassis Service Manual and/or a vacuum system trouble shooting guide?
Regards,
Alan
Someone recently posted that they cured their long time wiper door rising by replacing the vacuum valve located in the wiper bay under the right side wiper transmission…. but your troubles could easily be caused by something else.
It's good to be able to test the individual components to determine what's working and what's not rather than just buying parts until you happen to replace the one causing the problem.
No, the door should stay closed upon start up.
I wish I could say it's easy to find the cause but it's not.
Do you have a Chassis Service Manual and/or a vacuum system trouble shooting guide?
Regards,
Alan
Someone recently posted that they cured their long time wiper door rising by replacing the vacuum valve located in the wiper bay under the right side wiper transmission…. but your troubles could easily be caused by something else.
It's good to be able to test the individual components to determine what's working and what's not rather than just buying parts until you happen to replace the one causing the problem.
Drifting
Joined: Jul 2006
Posts: 1,259
Likes: 154
From: Deplorableville Nebraska
Alan is right, The most common issue for wiper door winking on startup is the wiper safety valve located under the passenger side wiper arm. There could be another issue or a combination also.
Do you have a Mityvac or equivalent vacuum pump? If so, report back and we can talk you through a test sequence to make a correct diagnosis.
You could also try bypassing the safety valve to check it's operation. There are 3 ports on the valve. Ignore the top one. it is only a vent. Pull the middle and the lower vacuum hoses off the valve and connect them with a small short tube.
Start the car, and if the "winking" went away, you found your problem. DO NOT replace it with the $25-$30 valve everyone sells, they are junk. Willcox sells the good one.
Do you have a Mityvac or equivalent vacuum pump? If so, report back and we can talk you through a test sequence to make a correct diagnosis.
You could also try bypassing the safety valve to check it's operation. There are 3 ports on the valve. Ignore the top one. it is only a vent. Pull the middle and the lower vacuum hoses off the valve and connect them with a small short tube.
Start the car, and if the "winking" went away, you found your problem. DO NOT replace it with the $25-$30 valve everyone sells, they are junk. Willcox sells the good one.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
No, it is not "normal" for the wiper door to do that....but it is NOT unusual for that to happen.
When it does, it's usually because of a bad check valve...and/or... a bad wiper blade safety switch (under right-hand wiper)...and/or... the steel tubing vacuum line (runs under the wiper motor across the firewall) having blockage at the low portion of the tubing.
The check valve and switch can be checked out before replacement; the cross-tube can be blown clear with compressed air (after removing tubing from both ends). The wiper safety switch can be misadjusted (up/down) because there is not enough 'slop' in the elongated holes, also. If that is the problem, open up those holes to get more travel.
When it does, it's usually because of a bad check valve...and/or... a bad wiper blade safety switch (under right-hand wiper)...and/or... the steel tubing vacuum line (runs under the wiper motor across the firewall) having blockage at the low portion of the tubing.
The check valve and switch can be checked out before replacement; the cross-tube can be blown clear with compressed air (after removing tubing from both ends). The wiper safety switch can be misadjusted (up/down) because there is not enough 'slop' in the elongated holes, also. If that is the problem, open up those holes to get more travel.
Last edited by 7T1vette; Jun 26, 2016 at 10:51 AM.
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
No, it is not "normal" for the wiper door to do that....but it is NOT unusual for that to happen.
When it does, it's usually because of a bad check valve...and/or... a bad wiper blade safety switch (under right-hand wiper)...and/or... the steel tubing vacuum line (runs under the wiper motor across the firewall) having blockage at the low portion of the tubing.
The check valve and switch can be checked out before replacement; the cross-tube can be blown clear with compressed air (after removing tubing from both ends). The wiper safety switch can be misadjusted (up/down) because there is not enough 'slop' in the elongated holes, also. If that is the problem, open up those holes to get more travel.
When it does, it's usually because of a bad check valve...and/or... a bad wiper blade safety switch (under right-hand wiper)...and/or... the steel tubing vacuum line (runs under the wiper motor across the firewall) having blockage at the low portion of the tubing.
The check valve and switch can be checked out before replacement; the cross-tube can be blown clear with compressed air (after removing tubing from both ends). The wiper safety switch can be misadjusted (up/down) because there is not enough 'slop' in the elongated holes, also. If that is the problem, open up those holes to get more travel.
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
By the way, I found a check valve on e-bay and it also comes with a filter of some sort. I cant find that filter on my car anywhere so I'm assuming that it was removed at some point in the cars history. Where is the filter supposed to be installed? Does it go in the line that feeds the check valve? Here's the e-bay auction:
http://www.ebay.com/itm/1968-1982-Co...VRnabV&vxp=mtr
http://www.ebay.com/itm/1968-1982-Co...VRnabV&vxp=mtr
Le Mans Master
Joined: Jun 2006
Posts: 6,399
Likes: 1,226
From: Tampa Florida
By the way, I found a check valve on e-bay and it also comes with a filter of some sort. I cant find that filter on my car anywhere so I'm assuming that it was removed at some point in the cars history. Where is the filter supposed to be installed? Does it go in the line that feeds the check valve? Here's the e-bay auction:
Team Owner
Joined: Sep 2006
Posts: 31,202
Likes: 4,287
From: Westminster Maryland
Hi TG,
The small hose goes through the firewall and supplies vacuum to the 'control' side of the system while the large hose travels across the mater cylinder to a tee that has a short hose that leads to the vacuum storage tank and the large hose continues forward to the headlights..
Regards,
Alan
The small hose goes through the firewall and supplies vacuum to the 'control' side of the system while the large hose travels across the mater cylinder to a tee that has a short hose that leads to the vacuum storage tank and the large hose continues forward to the headlights..
Regards,
Alan
Last edited by Alan 71; Jun 26, 2016 at 03:27 PM.
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Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
Hi TG,
The small hose goes through the firewall and supplies vacuum to the 'control' side of the system while the large hose travels across the mater cylinder to a tee that has a short hose that leads to the vacuum storage tank and the large hose continues forward to the headlights..
Regards,
Alan
The small hose goes through the firewall and supplies vacuum to the 'control' side of the system while the large hose travels across the mater cylinder to a tee that has a short hose that leads to the vacuum storage tank and the large hose continues forward to the headlights..
Regards,
Alan
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
Alan is right, The most common issue for wiper door winking on startup is the wiper safety valve located under the passenger side wiper arm. There could be another issue or a combination also.
Do you have a Mityvac or equivalent vacuum pump? If so, report back and we can talk you through a test sequence to make a correct diagnosis.
You could also try bypassing the safety valve to check it's operation. There are 3 ports on the valve. Ignore the top one. it is only a vent. Pull the middle and the lower vacuum hoses off the valve and connect them with a small short tube.
Start the car, and if the "winking" went away, you found your problem. DO NOT replace it with the $25-$30 valve everyone sells, they are junk. Willcox sells the good one.
Do you have a Mityvac or equivalent vacuum pump? If so, report back and we can talk you through a test sequence to make a correct diagnosis.
You could also try bypassing the safety valve to check it's operation. There are 3 ports on the valve. Ignore the top one. it is only a vent. Pull the middle and the lower vacuum hoses off the valve and connect them with a small short tube.
Start the car, and if the "winking" went away, you found your problem. DO NOT replace it with the $25-$30 valve everyone sells, they are junk. Willcox sells the good one.
Drifting
Joined: Jul 2006
Posts: 1,259
Likes: 154
From: Deplorableville Nebraska
What's the matter with the 25-30 dollar valve, why are they junk?
Full disclosure here, I manufacture the valves Willcox sells. I have spent an inordinate amount of time and considerable expense to design a valve that would function as it should, and last for a long time. I had to fully research exactly what the valve was supposed to do, and when it was supposed to happen. I then diagnosed the issues the current valve had, and designed mine around all the faults. The bottom line is my valves work.
We put up with some real junk out there in the market place with the importers of our parts. The real fault lies with the retailers. If they want cheap parts, that's what they (and we) will get. I only hope my valves will help guys out who want their cars to function as they should.
OK, off the soap box.........
Here's some links to past threads for more information.
https://www.corvetteforum.com/forums...n-on-69-a.html
https://www.corvetteforum.com/forums...5638487-a.html
https://www.corvetteforum.com/forums...-question.html
Good luck with your car!
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
Alan is right, The most common issue for wiper door winking on startup is the wiper safety valve located under the passenger side wiper arm. There could be another issue or a combination also.
Do you have a Mityvac or equivalent vacuum pump? If so, report back and we can talk you through a test sequence to make a correct diagnosis.
You could also try bypassing the safety valve to check it's operation. There are 3 ports on the valve. Ignore the top one. it is only a vent. Pull the middle and the lower vacuum hoses off the valve and connect them with a small short tube.
Start the car, and if the "winking" went away, you found your problem. DO NOT replace it with the 25-$30 valve everyone sells, they are junk. Willcox sells the good one.
Do you have a Mityvac or equivalent vacuum pump? If so, report back and we can talk you through a test sequence to make a correct diagnosis.
You could also try bypassing the safety valve to check it's operation. There are 3 ports on the valve. Ignore the top one. it is only a vent. Pull the middle and the lower vacuum hoses off the valve and connect them with a small short tube.
Start the car, and if the "winking" went away, you found your problem. DO NOT replace it with the 25-$30 valve everyone sells, they are junk. Willcox sells the good one.
Last edited by TheGreek!; Jun 27, 2016 at 11:04 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
If you have a vacuum operated wiper door, you have the vacuum transfer pipe. It connects the red striped vacuum line coming out of the firewall grommet on the driver's side (3 hoses in that grommet) to the red striped vacuum hose going into the 3-line grommet on the passenger side of the firewall. The hose coming out the driver's side is from the wiper vacuum solenoid/switch (behind tach) and the one on the other side goes to the wiper safety switch (under the right wiper blade).
No way for them to work if that metal tube (pipe) is not there. There is a "V" bend in the line below the wiper motor. That low spot is where 'stuff' can collect and partially block off that line. This can change the operating dynamics of the wiper door.
No way for them to work if that metal tube (pipe) is not there. There is a "V" bend in the line below the wiper motor. That low spot is where 'stuff' can collect and partially block off that line. This can change the operating dynamics of the wiper door.
Last edited by 7T1vette; Jun 27, 2016 at 11:23 PM.
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
If you have a vacuum operated wiper door, you have the vacuum transfer pipe. It connects the red striped vacuum line coming out of the firewall grommet on the driver's side (3 hoses in that grommet) to the red striped vacuum hose going into the 3-line grommet on the passenger side of the firewall. The hose coming out the driver's side is from the wiper vacuum solenoid/switch (behind tach) and the one on the other side goes to the wiper safety switch (under the right wiper blade).
No way for them to work if that metal tube (pipe) is not there. There is a "V" bend in the line below the wiper motor. That low spot is where 'stuff' can collect and partially block off that line. This can change the operating dynamics of the wiper door.
No way for them to work if that metal tube (pipe) is not there. There is a "V" bend in the line below the wiper motor. That low spot is where 'stuff' can collect and partially block off that line. This can change the operating dynamics of the wiper door.
Last edited by TheGreek!; Jun 27, 2016 at 11:38 PM.
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
Drifting
Joined: Jul 2006
Posts: 1,259
Likes: 154
From: Deplorableville Nebraska
If the bypass test on the safety valve doesn't work, it could be any other component in the control circuit. The control circuit is the small vacuum line that ultimately switches the vacuum relay. From this point, no one can tell you exactly what the problem is, we are only speculating which component is failing.
The bottom line is the control circuit is lagging behind the actuating circuit. The reason is the control circuit is letting atmosphere into the line (leaking vacuum if you will), causing an imbalance. The culprit could be any one of these:
vacuum relay
safety valve
override switch
wiper door solenoid
headlight switch
check valve
any of the connected hoses
The proper way to repair the wiper door is to diagnose the problem. If you can get hold of a Mityvac (or equivalent) hand pump, or even a vacuum gauge, you can do it easily.
I can help you if you want. Let me know and I will give you my number.
The bottom line is the control circuit is lagging behind the actuating circuit. The reason is the control circuit is letting atmosphere into the line (leaking vacuum if you will), causing an imbalance. The culprit could be any one of these:
vacuum relay
safety valve
override switch
wiper door solenoid
headlight switch
check valve
any of the connected hoses
The proper way to repair the wiper door is to diagnose the problem. If you can get hold of a Mityvac (or equivalent) hand pump, or even a vacuum gauge, you can do it easily.
I can help you if you want. Let me know and I will give you my number.
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
If the bypass test on the safety valve doesn't work, it could be any other component in the control circuit. The control circuit is the small vacuum line that ultimately switches the vacuum relay. From this point, no one can tell you exactly what the problem is, we are only speculating which component is failing.
The bottom line is the control circuit is lagging behind the actuating circuit. The reason is the control circuit is letting atmosphere into the line (leaking vacuum if you will), causing an imbalance. The culprit could be any one of these:
vacuum relay
safety valve
override switch
wiper door solenoid
headlight switch
check valve
any of the connected hoses
The proper way to repair the wiper door is to diagnose the problem. If you can get hold of a Mityvac (or equivalent) hand pump, or even a vacuum gauge, you can do it easily.
I can help you if you want. Let me know and I will give you my number.
The bottom line is the control circuit is lagging behind the actuating circuit. The reason is the control circuit is letting atmosphere into the line (leaking vacuum if you will), causing an imbalance. The culprit could be any one of these:
vacuum relay
safety valve
override switch
wiper door solenoid
headlight switch
check valve
any of the connected hoses
The proper way to repair the wiper door is to diagnose the problem. If you can get hold of a Mityvac (or equivalent) hand pump, or even a vacuum gauge, you can do it easily.
I can help you if you want. Let me know and I will give you my number.
Last edited by TheGreek!; Jun 28, 2016 at 01:22 AM.
Race Director
Joined: Oct 2008
Posts: 19,172
Likes: 1,668
From: Long Island
If you have a vacuum leak on a headlight vacuum actuator the wiper door will open, then close.. I just found the leak on the left headlight actuator - just started having that wiper door problem and found the leak. 
I have A/C so it's a PIA to replace.. hoping to do it this winter if the leak doesn't get worse...
I have A/C so it's a PIA to replace.. hoping to do it this winter if the leak doesn't get worse...